Patent Application
20210094140
This application claims priority to German Patent Application DE 10 2019 214 869.7 filed Sep. 27, 2019, the entirety of which is incorporated herein by reference.
The invention relates to a honing machine for honing a bore in a workpiece.
Honing is a cutting machining method using geometrically undefined cutting edges, in the case of which a honing tool performs a cutting movement composed of two components and there is constant areal contact between one or more cutting material bodies, for example honing strips, of the honing tool and the bore inner surface to be machined. The kinematics of a honing tool are characterized by a superposition of a rotational movement and a stroke movement running in an axial direction of the bore. Normally, an optional expansion movement is also provided, which leads to a variation of the effective diameter of the honing tool.
A one-off stroke movement of the honing tool within the bore, composed of an advancement into the bore and a subsequent retraction out of the bore, is referred to as “bobbing”. A repeated stroke movement within the bore, that is to say an advancement into the bore, followed by a cyclic reciprocating movement within the bore, and a subsequent retraction out of the bore at the end, is referred to as “oscillating”.
In the case of oscillating honing processes, an expansion movement is generally required, because the effective diameter of the honing tool is actively varied during the oscillation. Additionally, the wear of the cutting material bodies is generally compensated by means of the expansion movement.
The kinematics of the honing tool generate a surface structure with criss-crossing machining marks on the bore inner surface. Surfaces finish-machined by honing can satisfy extremely high demands with regard to dimensional and shape tolerances, and in some cases have a special surface roughness and structure, such as for example a plateau surface, which combines low wear owing to a high material contact area with the capability of being able to readily receive an oil film for lubrication. Therefore, many highly loaded sliding surfaces in engines or engine components, for example cylinder running surfaces in engine blocks or bore inner surfaces in housings of injection pumps, are machined by honing.
A honing machine is a machine tool suitable for the honing of bores in workpieces. Said honing machine has at least one honing unit which is mounted on a support structure fixed to the machine, for example a stand, a column or a frame. A honing unit comprises a spindle unit in which a spindle shaft is rotatably mounted. The spindle shaft is rotatable about its spindle axis by means of a rotary drive and, at a tool-side end, has a device for the fastening of a honing tool. A linear guide system is arranged between the main support and the spindle unit, which linear guide system serves for guiding a linear stroke movement of the spindle unit relative to the main support. To generate the stroke movement of the spindle unit parallel to the spindle axis, a stroke drive is provided. In general, an expansion drive for expanding the honing tool is furthermore provided. The expansion drive may for example be coupled to an advancing rod which runs in the interior of the spindle shaft.
The areal contact of the cutting material bodies with the bore inner surface generates a coaxial machining action, such that the axis of the bore and the axis of the honing tool align with one another. In general, the workpiece and/or the honing tool are provided with movement degrees of freedom such that the bore and the honing tool can align with one another.
A honing machine is intended generally to be usable flexibly for different types of workpieces having different workpiece heights and bore lengths.
In the case of tall workpieces or workpieces having long bores, use is typically made of a honing unit which permits a large stroke length since a long honing tool has to be used and the latter has to oscillate for a long distance in the workpiece and furthermore also has to retract out of the workpiece. The long main body necessary for a large stroke length is expediently mounted relatively far upwards on the support structure so that, when required, the tall workpiece can be transported in the associated large workpiece receptacle through to below the lower edge of the main body. Depending on the design of the machine cladding, a machine roof arranged at a relatively high point may be necessary. A centre of gravity located at a relatively high point may also arise for the arrangement, which can lead to instability during operation.
In contrast thereto, for a low workpiece (i.e. for a workpiece having a low workpiece height) with the short bore and high requirements regarding the machining quality, use is preferably made of a honing tool which is as short as possible in order to be able to ensure as low a concentricity error as possible at the honing tool. At the same time, the workpiece receptacle is intended generally to be as small and light as possible so that little mass and little mass moment of inertia result in low resetting forces during the machining and thus in good workpiece quality. Only a small stroke of the spindle unit is necessary, and the spindle unit should be mounted close above the workpiece receiving device so that the honing tool can reach the workpiece. However, in said installation position of the main support close to the workpiece, a large workpiece receiving device may possibly no longer be able to be transported through below the main support.
Depending on the workpiece to be machined in each case, on the associated workpiece receptacle (rigid, floating, cardanic), on the honing tool arrangement selected for this purpose (rigid honing tool or articulated rod) and on the selected type of machine (for example transfer machine with pallet circulation, single or two spindle machine with geared table, rotary table machine with geared table or NC table, special-purpose machine or the like), in each case a vertical installation position, suitable specifically for the workpiece to be machined, of the honing unit in the honing machine or on the support structure thereof is conventionally defined, which can be achieved precisely only to a limited extent, for example by means of different grid layout in the machine stands, honing units and optionally on a carriage plate supporting the spindle unit. This workpiece-specific design of the honing machine greatly restricts the possible variety of workpieces which can be machined on the respective honing machine.
It is an object of the invention to provide a honing machine of the type mentioned at the beginning which, without modification to the honing unit, can machine a great spectrum of workpieces having different workpiece heights.
To solve this problem, the invention provides a honing machine having the features of claim 1. Advantageous refinements are specified in the dependent claims. The wording of all the claims is incorporated in the content of the description by reference.
According to the claimed invention, a honing machine of the type mentioned at the beginning is optimized in respect of a plurality of parameters necessitated by the machine design in such a manner that a large spectrum of workpieces having different workpiece heights can be machined without modification work to the honing unit having to be undertaken. A plurality of properties of the honing machine are expediently adapted to one another here in order to achieve this aim. Firstly, the axial installation position of the main support on the support structure is taken into account. The term “axial installation position” refers here to the installation position in a direction parallel to the spindle axis. If the spindle axis, as in preferred embodiments, is oriented vertically, the axial installation position of the main support thus corresponds to the installation position with respect to the height of the main support. Furthermore, the usable length of the linear guide system and the properties of the stroke drive are taken into consideration. These parameters together predetermine a stroke length and a stroke position of the honing machine.
The term “stroke position” refers here to the entirety of all of the axial positions, which can be reached by means of the stroke drive along the linear guide system, of the tool-side end of the spindle shaft. This is also referred to in this application as “spindle nose” and refers to the location of the spindle unit closest to the workpiece. In the case of a vertically oriented spindle axis, the stroke position thus refers to the region between the axial position, that is the highest reachable because of the design, and the lowest reachable axial position, closest to the workpiece, of the tool-side end of the spindle shaft. The stroke position thus comprises the range of all of the axial positions that can be covered by the oscillating reciprocating movement during the machining of the workpiece and also that region which can be used after the machining in order to retract the honing tool from the workpiece, and also that region which, depending on the size of the workpieces and tools, may possibly not be reached without a mechanical collision of honing tool and honing machine.
The term “stroke length” refers to the axial distance between the structurally possible workpiece-remote axial end position of the stroke movement of the tool-side end of the spindle shaft and the structurally possible workpiece-close axial end position of the stroke movement of the tool-side end of the spindle shaft.
The stroke position differs conceptually and substantively from the stroke length. While the stroke length describes which distance lies between a highest and the lowest point which the stroke axis (with stroke drive and linear guide system) can dynamically reach within the honing machine, the stroke position describes the absolute position of said two points, i.e. the static installation position of the main support and of the units supported by the latter on the honing machine.
The terms “stroke length” and “stroke position” therefore relate to the mechanical construction of the honing machine. The workpiece-specific machining programs have to move within said mechanical limits. This applies, inter alia, to the length of the stroke movement during an oscillating working movement of the honing tool. This length is also referred to here as “oscillation length”. Furthermore, the travel distances of the spindle unit out of the workpiece into a retracted basic position have to lie within said mechanically defined limits. In the retracted basic position, it has to be possible, for example, to move the workpiece further perpendicularly to the axial direction of the spindle axis, or to remove said workpiece.
According to the claimed invention, the main support is attached to the support structure in such a manner that a workpiece-close end of the main support lies at a distance above a spindle-facing limit of a selected workpiece height range. Furthermore, the spindle unit is attached with respect to the linear guide system in such a manner that, in the structurally possible workpiece-close end position of a stroke movement of the spindle unit, the tool-side end of the spindle shaft lies closer to the workpiece height range than the workpiece-near end of the main support.
The spindle nose can thus be moved (in so far as the workpiece height permits this) into an axial position which lies closer to the workpiece than the workpiece-close end of the main support. This workpiece-close end position that is possible because of the design must not be reached during the set-up honing process. Particularly in the case of relatively tall workpieces, the lower (workpiece-close) reversing point of the oscillation movement of the spindle nose actually reached during the honing process may be located further away from the workpiece than the workpiece-close end of the main support.
The workpiece connection or the device for fastening a honing tool is located at the workpiece-close end of the spindle shaft, i.e. at the “spindle nose”. The term “workpiece height range” characterizes the height spectrum of those workpieces of differing height that are intended to be machined with the honing machine without modification of the latter. The spindle-facing limit of the workpiece height range is thus defined by the height of the tallest workpiece to be machined together with the workpiece receptacle provided for this purpose. As viewed in the axial direction, i.e. as viewed in a direction parallel to the spindle axis, the main support is therefore intended to be attached in an axial position such that the tallest workpiece to be chucked cannot collide with the workpiece-close end of the main support when the workpiece is transported past the main support perpendicularly to the spindle axis. At the same time, the spindle unit is intended to be attached with respect to the linear guide system in such a manner that, when required, the workpiece-side end of the spindle shaft, i.e. the spindle nose, can be moved past the workpiece-close end of the main support in the direction of the workpiece, i.e. can be positioned in a position closer to the workpiece than the workpiece-close end of the main support. When a spindle axis is oriented vertically, the axial height of the lower edge of the main support would thus be positioned higher than the axial position of the spindle nose at the workpiece-close reversing point of a possible stroke movement.
If a structural compromise is observed within the scope of these specifications, workpieces from a large workpiece height spectrum can be machined without modification of the honing machine being required when changing between workpieces of differing heights and without the overall construction of the honing machine becoming unnecessarily large.
For a honing machine with a vertically oriented spindle axis, it is possible, for example, by optimizing stroke length and stroke position or stroke length and installation position of the honing unit in the honing machine for a defined height of a machine roof, to achieve the effect that, firstly, a workpiece receptacle of maximum size (for a relatively tall workpiece), but, secondly, also a very low workpiece receptacle for a low workpiece to be precisely machined) can be machined equally in one and the same installation position of the honing unit in the honing machine without the workpiece receptacle being unnecessarily tall for the small workpiece or the associated honing tool being unnecessarily long. The honing machine thereby gains a high degree of flexibility.
At the same time, a conventionally provided great variance in linear guide systems of differing length can be reduced to a single standard length, and therefore only one version of a linear guide system has to be structurally maintained. This version can be produced for this purpose in relatively large production batches and thus more cost-effectively with consistently high quality. The same currently applies to other assemblies, for example to long carriage assemblies. The mutual coordination hitherto necessary in conventional systems of workpiece receptacles and honing tools prior to the installation of the honing machine can be omitted, and therefore a honing machine can basically always be constructed identically for a predetermined workpiece height spectrum. During the operating time of the honing machine, new or differently configured workpieces can be retrospectively introduced into the machining process without having to carry out a time-consuming and costly conversion.
In addition, the honing machine can be surrounded, when required, with a closed machine cladding which can also be closed upwards by a machine roof. This reduces the noise which can be emitted by the machining into the respective factory building, prevents the penetration of dirt from the surroundings into the honing machine and into the machining medium used (for example honing oil or cooling lubricant) and provides the possibility of installing an extraction system which can remove the arising atomization of the coolant to the outside from the machining room.
A honing machine of the type under consideration here has only a single linear guide system, wherein a usable length of the linear guide system and the stroke drive are configured in such a manner that different stroke positions within a stroke position range between a workpiece-close stroke position limit (workpiece-close axial end position) and a workpiece-remote second stroke position limit (axial end position) of the spindle nose and also different stroke lengths of an oscillating stroke movement are possible. The stroke drive and the linear guide system serve here both for setting the stroke position and for generating the oscillation movement with a predeterminable oscillation length.
In some embodiments, the spindle unit is mounted on a carriage which runs on guide rails of the linear guide system. The spindle unit can be mounted there in such a manner that the tool-side end of the spindle shaft (the spindle nose) projects over a workpiece-side end of the carriage to the workpiece side. The carriage can thus be moved as far as the end of the movement distance permitted by the linear guide system, and the spindle nose can be moved beyond said end and optionally beyond the workpiece-close end of the main support in the direction of the workpiece. This is of advantage particularly for the use of short honing tools.
However, such a carriage is not compulsory. It is also possible to fasten the guide shoes, which are guided on guide rails of the linear guide system, to individual fastening surfaces of the spindle unit without the interposition of a carriage plate common to the guide shoes. This likewise provides the possibility of mounting the carriage unit in such a manner that, at the tool-side end of the linear guide system, the spindle nose can be brought up very close to the workpiece.
The honing machine is preferably designed for use of honing tools of differing length of a honing tool group in such a manner that, when the longest honing tool of the honing tool group is used, a workpiece-close end of the honing tool is retracted at least as far as the workpiece-close end of the main support when the spindle unit is in a workpiece-remote end position of the stroke movement. As a result, a collision-free workpiece transport perpendicular to the spindle axis is ensured even when the longest honing tools of the honing tool group are used.
According to the inventors' experiences, an advantageous effect on the variability of the honing machine with simultaneously good stability can be provided if one or more of the following conditions are met. For example, a structurally possible projecting length of the tool-side end of the spindle shaft over the workpiece-close end of the main support can lie in the range from 20% to 40% of the stroke length. Alternatively or additionally, the upper limit of the workpiece height range can be 50% to 75% of the stroke length. Alternatively or additionally, the stroke length may be in the range of from 70% to 90% of the length of the spindle unit. Deviations from said dimensioning conditions may be provided and may be expedient.
In order to be able to realize as large a stroke length as possible with as small a length of the main support as possible, the moving parts of the honing unit, i.e. in particular the spindle unit and a carriage possibly provided for supporting the spindle unit, are intended to be designed to be as short as possible in the axial direction. It can thus be provided, for example, to design the rotary drive and the expansion drive to be as short as possible axially, for example by the use of direct drives which can be fully integrated in a spindle housing. For example, the rotary drive can be integrated in the spindle unit, i.e. can be arranged within a spindle housing accommodating the spindle shaft. A stator of the rotary drive can be connected to the spindle housing for rotation therewith, while a rotor is connected to the spindle shaft for rotation therewith.
An expansion drive for expanding the honing tool is preferably provided, wherein the expansion drive is coupled to an advancing rod which runs in the interior of the spindle shaft. The expansion drive is preferably designed as an electric direct drive, in particular as a torque motor or as a moving coil drive. An electric direct drive can be realized in an axially short design.
In order to be able to realize as large a stroke length as possible with a compact design, in preferred embodiments the stroke drive is designed as an electric linear motor with a primary part and a secondary part which are movable relative to one another parallel to the longitudinal direction of the longitudinal guide system (nominally parallel to the spindle axis). The primary part is preferably attached on the spindle unit side. A row of permanent magnets can be arranged within the main support in order, without an interconnected transmission or the like, to achieve a linear movement of the primary part in relation to the secondary part, which is provided with permanent magnets.
In preferred embodiments, the honing machine has a workpiece transport system with a plurality of workpiece receptacles which are selectively movable into a machining position in which a bore which is to be machined in a held workpiece is arranged coaxially with respect to the spindle axis. A plurality of workpieces transportable by the workpiece transport system can thus be machined successively at one and the same honing unit. The transport direction preferably runs exclusively perpendicularly to the spindle axis, and therefore the workpiece transport system does not require a dedicated stroke axis. Owing to the favourable geometrical design of the honing machine, workpieces of differing heights can be transported from the workpiece height range by means of the workpiece transport system without a collision between workpiece and main support of the honing unit being able to occur.
In preferred embodiments, the workpiece transport system comprises a rotary table which is rotatable about an axis of rotation and has a table panel which, on a partial circle about the axis of rotation, has a plurality of workpiece receptacles for holding a respective workpiece, which workpiece receptacles are selectively movable by means of the rotary table into a machining position in which a bore which is to be machined is arranged coaxially with respect to the spindle axis. A particularly compact design of the honing unit in the transverse direction with a large number of workpiece receptacles which can be simultaneously occupied can be realized with the aid of the rotary table transfer.
In some embodiments, the spindle unit has a spindle unit housing which has a first housing portion for accommodating the rotary drive and a second housing portion for accommodating the expansion drive. The spindle unit housing may be composed of a plurality of housing parts, but is preferably a single-piece component, which can be advantageous, inter alia, for reasons of stability and the precise alignment of the components of the spindle unit. Preferably, the rotary drive is accommodated in an exchangeable first cartridge and the expansion drive is accommodated in a second cartridge which is exchangeable independently of the first cartridge, wherein the first cartridge can be introduced into the first housing portion and the second cartridge can be introduced into the second housing portion. The two cartridges can be introducible into the spindle unit housing from opposite sides. The movability of the spindle unit housing within the stroke range facilitates the installation and the exchange of cartridges.
If a honing machine according to the claimed invention is designed for different workpiece heights from a workpiece height spectrum of interest, then by determination of the ideal position of the honing unit in the honing machine, a continuous standardization is possible, permitting a significantly greater diversity of workpieces with different workpiece heights to be machined by means of the honing machine and at the same time enabling the honing machine to always be constructed identically. Furthermore, a uniformly dimensioned machine cladding can generally be used since the machine roof thereof is not too high.
Further advantages and aspects of the invention will emerge from the claims and from the following description of preferred exemplary embodiments of the invention, which are explained below on the basis of the figures:
The honing machine 100 has a substantially rectangular machine base 110 with a frame and a base plate which is or should be oriented horizontally in the case of a fully set-up honing machine. The rectangular base plate is somewhat longer in the first direction (longitudinal direction) running parallel to the y axis of the machine coordinate system MKS than in the second direction (transverse direction) which is perpendicular thereto and which runs parallel to the x axis of the machine coordinate system. Close to the rear side 114 of the machine base, in the vicinity of one of the longitudinal edges, there is arranged a vertical stand 120, which is fixedly screwed to the machine base. The vertical stand serves as a support structure 120 for a honing unit 130, which is mounted on the support structure in the region of the front side of the latter.
A major constituent part of the honing unit is a spindle unit 150 in which a spindle shaft 152 is rotatably mounted. To drive the spindle shaft, there is integrated a rotary drive or spindle motor which is integrated into the spindle unit and which can drive the spindle shaft about the spindle axis 155, that is to say about the axis of rotation of the spindle shaft 152, with a predefined rotational speed profile. The spindle shaft 152 has, at a tool-side end 153, which is also referred to as spindle nose, a device (tool receptacle) for the fastening of a honing tool 190.
The spindle unit 150 is mounted on the top side or front side of a carriage plate 165. The carriage plate is supported by a carriage box 160 which serves as the main support of the honing unit. Between the main support 160, which is formed by the carriage box, and the carriage plate 165 or the spindle unit supported thereby, there is provided a linear guide system (not visible in the illustrations) for guiding a linear stroke movement of the spindle unit 150 relative to the main support 160. In the example, the stroke drive has an electric linear motor with a primary part and a secondary part which are movable relative to one another parallel to the longitudinal direction of the longitudinal guide system (ideally also parallel to the spindle axis 155).
In the example, the primary part, which is operated with an electrical current, is attached to the carriage plate, or to the spindle unit 150 which is likewise operated with current, while a series of permanent magnets is arranged within the main support 160. A reversed arrangement is also possible.
The linear guide system has guide rails which are attached to the main support 160. The corresponding guide shoes are arranged on the bottom side of the carriage plate 165. There are also embodiments in which the guide shoes, which slide on the guide rails, are fastened to individual fastening surfaces of the spindle unit, without the interposition of a carriage plate which is common to the guide shoes.
The honing machine 100 is equipped with a workpiece transport system 180 which has a rotary table or a rotary indexing table. In the case of the illustrated rotary table transport system, a horizontally oriented table panel 184 is provided which, by means of a rotary drive arranged under the table panel, can be rotated in predefined angular steps about an axis of rotation 185 which is oriented nominally vertically (parallel to the z direction of the machine coordinate system). On a pitch circle about the axis of rotation 185, there are provided multiple (in the example, six) workpiece receptacles 182 for receiving one workpiece W each. During transportation, the table panel rotates through a particular angle (in this case 60°) about the axis of rotation 185, which is positioned fixedly in space, in order to successively arrange in steps in each case one workpiece W in a machining position under the honing unit 130 such that the spindle axis 155 corresponds as closely as possible to the bore axis in the workpiece W. Ideally, all workpiece receptacles are mounted so as to be as far as possible equally spaced apart from the axis of rotation 185 and as far as possible with a uniform circumferential spacing to one another. If multiple honing units or multiple honing stations are served by the rotary table transport system 180, then all honing units must be as far as possible aligned such that, in any transport position, there is as small as possible a spacing between the actual axis of rotation of the spindle motor and the bore axis in the workpiece. This means that all honing units must be correspondingly aligned in the honing machine.
The honing unit 130 is fastened by means of two fastening units 210-1, 210-2 to the front side of the stand or of the support structure 120. Here, the fastening units constitute a mechanical connection between the stand 120 (support structure 120), which is fixed with respect to the machine, and the main support 160 of the honing unit 130. The vertical spacing 212, measured in the z direction, between the effective centres of the fastening units 210-1, 210-2 amounts, in the example, to more than 30%, in particular more than 40% and/or less than 90% or less than 80% of the length, measured in the vertical direction, of the main support 160. The fastening units are not arranged at the outer ends of the main support 160 but rather are offset inwards. What is particularly advantageous is an arrangement such that the fastening units are positioned such that the guide shoes, which are situated on the carriage plate which supports the spindle unit, have as small a spacing as possible to the fastening units when the spindle unit is situated in a stroke position intended for the machining process. Then, it is possible in particular for the dynamic forces that arise during an oscillating stroke movement to be particularly readily accommodated.
The fastening units 210-1 and 210-2 simultaneously function as first setting unit 210-1 and second setting unit 210-2 of an alignment system 200, the components of which are arranged at least partially between the support structure 120 and the main support 160. By means of the alignment system 200, it is possible both for the position of the spindle axis 155 to be adjusted in continuously variable and reversible fashion along two mutually perpendicular axes of translation, and for the setting of the orientation (angular position) of the spindle axes to be adjusted in continuously variable and reversible fashion in relation to two mutually perpendicular axes of rotation. In this way, it is possible for the spindle unit as a whole to be aligned such that its axis (spindle axis 155) is aligned as closely as possible with the axis of the bore to be machined.
Each of the setting units 210-1, 210-2 offers exactly two translational setting degrees of freedom. In the case of a first setting degree of freedom, the structural height, measured parallel to the first direction (y direction), of the setting unit can be varied in continuously variable and reversible fashion within certain limits, such that the spacing 214, measured parallel to the first direction, between the support structure 120 and the main support 160 of the honing unit at the location of the fastening unit can be varied. First setting elements are provided for this purpose. In the case of the second setting degree of freedom, it is possible for those components of the setting unit which are fixedly connected to the main support 160 of the honing unit 130 to be displaced in continuously variable and reversible fashion, parallel to the second direction (x direction), relative to those components which are fixedly connected to the support structure 120. Second setting elements are provided for this purpose. There are components which belong both to the first and to the second setting elements and which thus have a dual function (for example a wedge element discussed in more detail further below).
These two translational setting degrees of freedom, together with the fact that the two setting units 210-1, 210-2 are arranged with a vertical spacing 212 to one another (measured along the z direction or the third direction), make it possible for the position of the spindle axis 155 to be set along two mutually perpendicular axes of translation (parallel to the first direction and parallel to the second direction) and, independently of this, also for the orientation of the spindle axis 155 in relation to two mutually perpendicular axes of rotation (in each case parallel to the first direction and to the second direction) to be set in continuously variable and reversible fashion.
If, for example, both setting units 210-1, 210-2 are adjusted in terms of their effective structural height such that the spacing 214, measured parallel to the first direction, between support structure 120 and main support 160 is changed by the same magnitude, the result is a change in the position of the spindle axis 155 by parallel displacement in a y-z plane, or a translation of the spindle axis 155 in the first direction. This corresponds to purely a change in position without a change in the orientation.
If no change in spacing, or a different change in spacing than that at the second setting unit 210-2, is set at the first setting unit 210-1, this results in a change in inclination of the spindle axis 155 within the y-z plane, which leads to a rotation of the spindle axis about a virtual axis of rotation which runs parallel to the second direction (x direction) perpendicular to the y-z plane. The result is thus a change in the orientation.
If a displacement parallel to the second direction (x direction) by the same displacement travel is set at the first setting unit 210-1 and at the second setting unit 210-2, the result is a parallel displacement of the spindle axis in an x-z plane or a translation of the spindle axis 155 in the second direction. This corresponds to purely a change in position without a change in the orientation.
If displacement travels of unequal length are set at the first setting unit 210-1 and at the second setting unit 210-2, this results in an adjustment of the inclination of the spindle axis in an x-z plane, which corresponds to a rotation about a virtual axis of rotation which runs parallel to the first direction.
The spatial position of the virtual axes of rotation that possibly arise is not fixed but rather varies in a manner dependent on the ratios of the variations performed at the two setting units.
Details of the construction of the first setting unit 210-1 or of the first fastening unit 210-1 of the alignment system 200 will now be discussed in more detail below with additional reference to
The setting unit 210-1 comprises a base element 220 which is composed of multiple components and which is designed for being mounted fixedly on the support structure 120 of the honing machine or on an adapter unit which is connected fixedly to the support structure. Furthermore, a wedge element 230 is provided which has a planar first wedge surface 231 facing towards the base element 220 and has a planar second wedge surface 232 which, in the assembled state, faces towards the main support 160. The wedge surfaces 231, 232 of the relatively flat wedge enclose a wedge angle 233 of approximately 5° to 6°. In the assembled state, the planar first wedge surface 231 lies a really against a planar sliding surface 221, facing towards said first wedge surface, of the base element 220. A relative displacement of the wedge element 230 relative to said sliding surface 221 of the base element along a displacement direction 238 running parallel to the x direction (second direction) is provided by the construction, whereas relative movements in other directions are prevented by the construction. The actuating devices which are provided for activating this relative displacement and which serve for displacing the wedge element 230 in the displacement direction and for positioning the wedge element in a target position will be discussed in more detail further below.
The base element 220 includes a spherical socket 222, which serves as a basis for the fastening unit and is provided for being fixedly screwed to the support structure of the honing machine at the fastening position provided for it. In some embodiments, an adapter unit with suitable assembly interfaces is also interposed between the spherical socket and the support structure. A cylindrical pin may be used for the orientation of the spherical socket 222 in terms of position on the support structure 120 or on an adapter provided for connecting to the support structure. Said cylindrical pin can define the rotative position of the spherical socket in a fitting bore of the support structure or of an adapter.
On the side facing towards the wedge element, there is formed a spherically curved sliding surface 223. In the assembled state, a spherical disc 224 lies in the spherical socket 222. Said spherical disc has, on the side facing towards the spherical socket, a convex spherical sliding surface 225 corresponding with the sliding surface 223, and has, on the side facing towards the wedge element, the planar sliding surface 221. A free rotation of the spherical disc 224 in the spherical socket 222 is prevented by virtue of the spherical socket having two cylindrical pins 228 which run in a groove in the spherical disc 224. Thus, only a limited rotation about an axis of rotation running parallel to the second direction is possible.
During the assembly process, the wedge element 230 is placed onto the spherical disc 224. Said wedge element may be displaced laterally in the displacement direction (parallel to the x direction) in order to be able to set the structural height, measured parallel to the y direction, of the setting element in continuously variable and reversible fashion. Firstly, the angle of the wedge element 230 should be shallow enough that it moves in the range of self-locking. Here, this means that a change in load on the wedge element should not trigger any lateral displacement of the wedge element. Secondly, however, the angle of the wedge element should also be steep enough that a sufficient range of adjustment in the height of the wedge element is present with the available lateral displacement travel of the wedge element 230. In the exemplary embodiment, the wedge angle 223 is dimensioned such that there is an integer ratio between a lateral displacement of the wedge element and the resulting change in height of the fastening unit or of the setting unit. A wedge with a corresponding ratio of 1:10 has proven highly suitable, such that a displacement by 1 mm causes a change in height by 0.1 mm.
Two tension anchors 229 are provided for facilitating the handling of the components during the assembly process. These each exert a slight pressure on the wedge element 230 via a helical spring, such that said wedge element is supported on the spherical disc 224 and thus prevents the wedge element from lifting off the spherical disc during the assembly process.
In the fixedly installed spherical socket 222, there is fixedly installed a substantially cuboidal holding block 226. In the holding block, there is seated a bearing bolt 227 on which the main support 160 can be supported during the mounting of the honing unit 130 onto the fastening unit 210-1, in order, during the assembly process, to compensate for the mass of the honing unit with respect to the Earth's gravitational force. The bearing bolt 227 has a circular outer contour at its side facing towards the honing unit. The main support 160 has, on its side facing towards the fastening unit, a rectangular pocket or recess 162 for receiving the bearing bolt, which in the received state ideally forms linear contact (or, in the case of relatively great angles of inclination, punctiform contact) with the rectangular pocket, such that no constraint is imparted even in the event of inclination of the honing unit.
On the upper fastening unit 210-1, the bearing bolt 227 is fitted relatively tightly in said pocket on the main support 160, in order already to fix the position of the honing unit in the honing machine relatively accurately during the assembly process. On the lower fastening unit 210-2, the pocket on the main support 160 of the honing unit is somewhat larger, such that no constraint is imparted to the honing unit here either.
In the wedge element 230, on opposite sides of the polygonal cutout provided for the passage of the holding block 226, there are provided threaded bores which are oriented substantially parallel to the second direction. Into the threaded bores, there are screwed setting screws 240-1, 240-2 which serve as actuating elements of an actuating device for displacing the wedge element 230 in the displacement device 238. By means of these setting screws, the wedge element can be displaced against the holding block 226 (which is attached fixedly with respect to the machine) in the displacement direction 238. The height adjustment of the fastening element and thus the spacing adjustment (in the y direction) between support structure and main support of the honing unit at the location of the setting unit is effected by displacement of the wedge element. When the desired target position has been attained, the wedge element automatically holds this position owing to self-locking. The wedge element can however be additionally fixed in this position by tightening of the setting screws which act against one another.
On the main body 160, at the location provided for the attachment of the fastening unit or setting unit 210-1, there is formed a planar oblique surface 164 which in the assembled state interacts, as a sliding surface, with the second wedge surface 232. In the main support 160 of the honing unit, there are furthermore formed threaded bores which run parallel to the x direction and in which setting screws 250-1, 250-2 are seated. Said setting screws are likewise supported on the holding block 226 (which is installed fixedly with respect to the machine). A displacement of the main support 160 of the honing unit relative to the support structure 120, which is fixed with respect to the machine, parallel to the displacement direction 238 is possible by actuation of the setting screws 250-1, 250-2. Here, the planar second wedge surface 232 and the oppositely situated planar oblique surface 164 on the main support slide on one another. Since this is associated with a minimal change in spacing in the y direction, the setting screws 240-1, 240-2 should also be adjusted to the same extent for the purposes of compensation.
A configuration such that each rotation of the setting screw results in a fixed extent of the displacement is advantageous. For example, in the case of a thread pitch of 1 mm, one full rotation of the setting screw 250-2 results in a displacement of 1 mm. By re-measuring the positions of the parts with respect to one another, the respectively set position can be read off, and the adjustment travel that is still required can be estimated.
The basic setting of the fastening units 210-1, 210-2 is the theoretical centre, such that, in this position, in the absence of all manufacturing tolerances of the honing machine, the axis of the spindle motor, that is to say the spindle axis 155, would run exactly in alignment with the bore axis in the workpiece. Proceeding from this central position, both the height of the setting units parallel to the first direction (y direction) and also the lateral offset by relative displacement parallel to the second direction (x direction) can be reversibly set independently of one another by means of the setting screws 240-1, 240-2 and 250-1, 250-2 respectively. A lateral displacement parallel to the x direction arises here from the setting screws 250-1, 250-2 in the main support. The setting of the height of the fastening unit in the y direction arises from the setting screws or forcing-off screws 240-1, 240-2 in the wedge element 230.
In order to vary the position of the honing unit relative to the bore axis in the workpiece, the upper setting unit 210-1 and the lower setting unit 210-2 are adjusted in each case in the same direction by the same setting travel. In order to adjust the angular position of the unit, the upper setting unit and the lower setting unit are adjusted in opposite directions and/or to different extents. In the case of the fastening units being set in opposite directions and/or to different extents, an angular offset between those wedge surfaces of the wedge elements which lie on the spherical segments can occur owing to the different heights of the two setting units. This angular offset can be compensated by means of small compensation movements of the spherical discs in the spherical sockets. Thus, the spherical bearings which are integrated into the fastening units 210-1, 210-2 and which have the complementary curved sliding surfaces serve as an angle compensation device for automatically compensating angular offsets, and stresses possibly caused as a result, in the case of adverse setting conditions of the setting units. In the example, the radius of curvature of the spherical sliding surfaces 223, 225 is selected such that (in the case of the wedge element being set into its central position) the sphere central point lies on the axis of rotation of the spindle motor, that is to say on the spindle axis 155. Thus, possible compensation movements do not have an effect on the position and orientation of the spindle axis.
A method for setting the machine geometry with alignment of the spindle axis in relation to the bore axis of the bore that is to be honed may for example progress as follows.
Firstly, the fastening units 210-1, 210-2 which serve as setting units are fastened at their intended positions to the front side of the support structure by means of screws. Here, the wedge elements and the spherical discs are each brought into a central position.
The honing unit is subsequently fitted by being mounted at the top and bottom on the bearing bolts 227. The main support 160 of the honing unit 130 is then brought into a central position.
For an alignment operation, as long as possible a cylindrical geometry with reference to the workpiece receptacle or to the transport system should be provided on the workpiece receptacle. For example, a master cylinder may be installed as an alignment aid at the location of a workpiece receptacle of the rotary table transport system. The cylindrical bore in the master cylinder thus represents the bore axis in the workpiece and produces the reference to the transport system. This step may be performed before or after the fitting of the honing unit on the support structure.
Thereafter, the parallelism of the axis of rotation of the spindle motor, that is to say the parallelism of the spindle axis with respect to the central longitudinal axis of the master cylinder, can be set for example by setting of the setting units in opposite directions and/or to different extents. Here, it is preferably firstly the case that the lateral setting (parallel to the displacement direction) is performed by means of the setting screws in the main support, and then the frontal setting is performed by displacement of the wedge elements.
Thereafter, the master cylinder can be dismounted, in order to measure a possible position offset of the spindle axis with respect to the setpoint position directly at those bores of the transport system in which the workpiece receptacles will later be installed.
If these measurements yield that a position offset is still required, then the position of the axis of rotation of the spindle motor with respect to the bore axis of the workpiece is set by adjustment of the setting elements in opposite directions to equal extents. Here, too, it is preferably the case that firstly the lateral position (position in the x direction) is set and subsequently the frontal position (position along the first direction or y direction) is set.
When the desired target position and target orientation have been attained with sufficient accuracy, then the setting screws of the setting units are tightened without further displacement of the components thereby actuated, in order to fix the relative positions assumed.
The support structure may, as shown, be for example a vertical stand, which possibly supports only a single honing unit. A honing machine may have two or more such stands. The support structure may also be a column, on the periphery of which multiple honing units are mounted in a circumferentially offset manner (cf. DE 20 2011 003 069 U1). Instead of the direct mounting of the fastening units on the support structure, as illustrated, an indirect fastening by means of an adapter provided for connecting to the support structure is also possible.
Special features of the construction of a spindle unit 300 which is provided in some embodiments will now be described on the basis of
The spindle unit 300 has a modular construction. The spindle unit housing 310 is constructed as a single-piece component and is also referred to here as a monocoque housing. The substantially tubular component, which is open at both sides, has a first housing portion 310-1, which accommodates the rotary drive 450, and a second housing portion 310-2, which is formed in one piece with said first housing portion and which has a smaller inner diameter than the first housing portion 310-1 and which is provided for accommodating the expansion drive 550.
The rotary drive 450 is arranged in an exchangeable first cartridge 400 and is mounted on the interior of the substantially rotationally symmetrical cartridge sleeve 410 of the first cartridge 400. The expansion drive 550 is arranged in a second cartridge 500 and is mounted within the cartridge housing 510 of the second cartridge.
The first cartridge 400 can be introduced into the first housing portion 310-1 from below. Independently of this, the second cartridge 500 with the expansion drive can be introduced into the second housing portion 310-2 from above. The expansion drive is coupled to an axially movable advancing rod 460 which, during the assembly of the spindle unit, is introduced into an inner passage bore of the spindle shaft 152 and, during the operation of the honing machine, acts on an axially displaceable expansion cone which is arranged in the interior of the honing tool.
The comparison of
The single-piece spindle unit housing 310, which may be produced for example from a torsionally resistant aluminium alloy or from a fibre composite material, serves as a mechanical reference for the mutual coaxial alignment of the two cartridges 400, 500 and of the components contained therein and also as a mechanical reference for establishing the correct alignment of said components of the spindle unit 300 in relation to the linear guide system of the stroke drive.
To ensure that each of the cartridges is installed in the correct alignment and in the correct axial position in relation to the associated housing portion of the spindle unit housing, corresponding fitting surfaces are formed on the outer sides of the respective cartridges and the inner sides of the associated housing portions. In
An outwardly projecting flange 415 is formed in the lower third on the cartridge housing 410 of the first cartridge 400. The upwardly pointing flange surface of said flange serves as an axial stop surface for the abutment against the end side 315 of the spindle unit housing and thus defines the axial position of the installed cartridge. Directly above the flange 415, there is situated a wide rotationally symmetrical fitting surface 416 which fits with the fitting surface 312. Above this, with a spacing, there is situated a further fitting surface 417, which fits with the upper fitting surface 313. The internally situated fit between the fitting surfaces 313 and 417 is formed with a smaller diameter than the external fit with the fitting surfaces 416 and 312 in the vicinity of the flange 415. It can thus be achieved that, during the assembly process, the respective fitting surfaces come into contact with one another only when the first cartridge 400 has been almost fully inserted into the spindle unit housing or the associated housing portion, and not already at the start of the insertion into the spindle unit housing.
A corresponding solution is also provided for the installation of the second cartridge 500 in the second housing portion 310-2. There, too, there are two fitting surface pairs, which are situated so as to be spaced apart from one another, and, on the widened head of the second cartridge 500, a stop surface 515 which, during the axial insertion of the second cartridge 500, abuts against the upper end side 316 of the spindle unit housing 310 and thus defines the axial position of the second cartridge 500 in the spindle unit housing. Thus, the correct alignment and axial position of the cartridges is set without further alignment work once the insertion of the cartridges has been completed during the mounting on the spindle unit housing.
One particular challenge consists in providing, in the spindle unit 300, suitable electrical and fluidic connections of the components installed in the first cartridge 400. Whereas the components of the second cartridge 500 which accommodates the expansion drive 550 can be contacted relatively easily directly from above by means of suitable connectors, contacting of the components (for example rotary drive) provided in the first cartridge 400 from below, that is to say from the side at which the honing tool is coupled on, is not possible or is possible only with restrictions.
In the exemplary embodiment, connection problems for the internal components of the first cartridge 400 are resolved by virtue of connecting elements of suitable plug-type connections being attached to the upper side of the first cartridge 400, that is to say to the inner side which is to face towards the second cartridge 500. Said connecting elements cooperate with corresponding connecting elements of a plug-type connection on a housing portion 318 of the spindle unit housing 310 at the stepped transition from the relatively large diameter in the first housing portion 310-1 to the relatively small diameter at the second housing portion 310-2.
In the exemplary embodiment of
The electrical plug contacts 475 serve for the supply of electrical power to the rotary drive 450 and the transmission of information relating to the rotary drive, for example from temperature sensors. The electrical connections 480 serve for the transmission of signals from encoders installed in the first cartridge 400, for example of a rotary encoder of the rotary drive, for the purposes of controlling the honing machine. The rotary encoder may be composed of a static and a rotating part, wherein the static part functions as a measuring head 485.
The associated plug sockets are attached to the downwardly pointing side of the housing portion 318 at the stepped transition between the relatively large inner diameter of the first housing portion 310-1 and the relatively small inner diameter of the second housing portion 310-2. The electrical and fluid connections are automatically produced in the final phase of the insertion, when the first cartridge 400 is inserted, in the correct rotational position, into the associated first housing portion 310-1. To ensure that the first cartridge can be introduced, and inserted as far as the stop, only in a single rotational position, a corresponding structure is provided.
Further special features of the machine concept of the exemplary embodiment will now be discussed in conjunction with
A relatively long honing tool 190-1 is accordingly required for the machining of the tall workpiece W1, whereas a relatively short honing tool 190-2 can be used for the machining of the short bore in the relatively short workpiece W2, which makes it possible to realize small concentricity errors and thus high levels of machining quality.
In the design of the honing unit 130, attention is paid inter alia to an optimum axial mounting position of the main support 160 or of the carriage box 160 on the support structure 120. Here, the main support 160 is attached to the support structure 120 such that an end 166 close to the workpiece, that is to say the bottom edge 166 of the carriage box or of the main support 160, lies with a spacing above the upper boundary WHO, facing towards the spindle unit, of the workpiece height range.
It is thus possible, during rotation of the rotary table or of the table panel 184 thereof about the rotary table axis 185, for even the tallest workpieces W1 to move through below the main support 160 without collision, if the spindle unit 150 has been retracted sufficiently far upwards. In this regard,
It is important here that the spindle unit 150 can also be moved further downwards in the direction of the workpiece if required, as will be discussed in more detail on the basis of
It can be seen from
In the case of a short honing tool 190-2 being used for machining the short bore of a short workpiece, the spindle unit 150 must be moved relatively far downwards or in the direction of the workpieces. Here,
Furthermore, owing to the use of electric direct drives for the rotary drive and the expansion drive, the spindle unit 150 is so short in an axial direction, that is to say parallel to the spindle axis, that, even in the stroke position most remote from the workpiece (
Tests performed by the inventors with regard to favourable dimensioning proportions have found that, for many practically relevant applications or workpieces, the workpiece height range may lie in the range from 250 mm to 500 mm, in particular in the range from 250 mm to 400 mm. The upper boundary WHO of the workpiece height range may thus lie for example 250 mm to 500 mm above a reference plane, wherein the reference plane is that plane on which the workpiece holding devices are mounted (that is to say for example the top side of the table panel). The bottom edge 166 of the main support may lie one or a few mm above this upper boundary. Expedient stroke lengths may lie for example in the range from 450 mm to 700 mm, in particular in the range from 500 mm to 650 mm. Expedient stroke positions may lie for example in the range from 150 mm to 900 mm, in particular in the range from 180 mm to 850 mm (likewise in relation to the reference plane mentioned above). Expedient lengths of the main support may lie for example in the range from 1000 mm to 1500 mm, in particular in the range from 1100 mm to 1400 mm. Expedient axial lengths of the spindle unit (measured from the spindle nose to the top side of the spindle unit housing) may lie for example in the range from 500 mm to 900 mm, in particular in the range from 600 mm to 800 mm. Typical tool lengths may lie for example in the tool length range from 100 mm to 150 mm (for the relatively short honing tools) up to 350 to 600 mm (for the relatively long honing tools).
Considering the structurally possible projecting length 167 of the spindle nose beyond the bottom edge 166 of the main support, this may lie for example in the range from 20% to 40% of the stroke length, in particular in the range from 25% to 35% of the stroke length. The upper boundary of the workpiece height range may for example amount to 50% to 75% of the stroke length, in particular 60% to 70%. The stroke length may for example lie in the range from 70% to 90% of the length of the spindle unit. Deviations from these dimensions and dimension proportions are self-evidently possible and may be expedient in particular cases.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102019214869.7 | Sep 2019 | DE | national |
