Patent Application
20200094368
The present invention relates to a honing tool for honing the inner surface of an opening in a workpiece, wherein the honing tool is designed according to the preamble of claim 1. The invention also relates to a hone strip having honing stones.
During honing, the respective honing tool is inserted into the opening to be machined. For this purpose, the honing tool can be moved into the stationary opening or the workpiece with the opening can be moved relative to the stationary honing tool such that the honing tool is inserted. Subsequently, the movement of a rotation in circumferential direction with superimposed up and down movement of the honing tool in axial direction within the opening is carried out, which is typical for hone machining. Also in this case, the workpiece or the honing tool or both can be moved so that the corresponding relative movement between workpiece and honing tool is present.
Conventional honing tools have a tool body that is solid, i.e. that has a one-piece base body, whereby this base body is usually made of a solid material. Usually the hone strips or honing stones and an infeed device usually in the form of an infeed cone attached to an infeed rod are arranged within the base body. Furthermore, lightweight honing tools are known which do not have a tool body with a solid base body, but a multi-piece tool body. With this lightweight construction, the tool body usually has plate-like elements extending orthogonally to the axial direction. Along the axial direction, usually elongated elements are provided which are bar-shaped or extend in a different manner in the axial direction and are connecting the plate-like elements. Such lightweight honing tools can be manufactured at low costs, however, in use only less precise results can be obtained than with conventional honing tools. Due to the lightweight construction, such tools are more susceptible to vibrations and oscillations during machining. When using lightweight honing tools, the machining of the opening is usually controlled by a timing or by a drop measuring sleeve.
It is the object of the present invention to provide a honing tool which can be manufactured with low costs and enables surface machining of the inner walls of an opening with improved accuracy. According to the invention, this object is achieved by a honing tool according to claim 1.
Another object is to provide a honing strip where honing stones can be easily replaced. According to the invention, this problem is solved by a hone strip according to claim 9. With conventional honing tools in lightweight construction, the honing stones are adhered onto the hone strips or attached to them in some other undetachable way. The replacement of the honing stones, when they are worn out by the machining, is complex, which has a negative effect on the operating costs. The honing tool according to the invention is of lightweight construction and therefore does not have a tool body with a solid base body, i.e. a base body made of one piece, but the tool body of the honing tool according to the invention comprises a cage-like structure of individual interconnected elements. The honing tool also comprises at least two hone strips configured for radial infeed. The term radial infeed means that the hone strips can be variably positioned in a radial direction orthogonal to the axial direction. The axial direction corresponds to the direction in which the honing tool is moved up and down. Preferably, the hone strips of the honing tool are arranged on the tool body evenly distributed in the circumferential direction. The individual hone strips can each carry one or more honing stones. With the honing tool according to the invention, the radial feedability of the hone strips is implemented by a rack-and-pinion gear. The hone strips are assigned to the respective gear racks. A hone strip can be feedable by means of a single toothed rack. It is, however, also within the spirit of the invention if each hone strip comprises at least two racks preferably arranged at a front end and a rear end, in axial direction, of the hone strips. However, other rack arrangements which permit radial infeed are also conceivable and within the spirit of the invention. These racks interact with a central toothed shaft to form the gearbox. By rotation of the toothed shafts, the racks can be moved and by this movement, the hone strips can be adjusted in their radial position.
In other words, the rotational movement of the rack relative to the tool body is converted by the rack gear into a translational movement of the racks relative to the tool body, allowing the hone strips to be moved translationally in a radial direction.
According to the invention, the honing tool comprises a pneumatic measuring device for in-process diameter measurement of a diameter of the opening to be machined in the workpiece. By means of this pneumatic measuring device, which can determine the diameter of the bore to be machined with high accuracy on the basis of a measured pressure, it is possible to precisely determine the progress of the honing process.
The tool body of the honing tool can be dividable into a functional section and a coupling section. The functional section supports the components relevant for honing, such as the hone strips and the pneumatic measuring device. The functional section and the coupling section can, for example, be formed by components that can be separated from each other. However, they can also be formed by the same components while the distinction is functional in nature, so that the honing operation is performed by the functional section and the coupling section forms an interface for coupling to a honing spindle. In particular, the coupling section may comprise an interface for coupling the honing tool to a honing spindle, e.g. in the form of a coupling flange. It can be advantageous if the functional section is gimbal-mounted relative to the coupling section. In particular, it is possible for the honing tool to virtually center itself in the opening to be machined, resulting in a particularly uniform surface finish. For example, the coupling section may comprise a flange that can be attached to a corresponding counter flange on the honing spindle. The toothed shaft of the rack-and-pinion gear typically extends through such a coupling flange. If the functional section is gimbal-mounted relative to the coupling section, the rack can additionally be connected via a cardan joint, by means of which the toothed shaft can be connected to an appropriate drive for the infeed of the hone strips on the side of the honing spindle.
The coupling flange of the coupling section can, for example, be constructed with a coupling plate on the spindle side. It is possible that extensions, in particular two extensions, extend from the coupling plate on the spindle side in axial direction into the functional section. Such extensions, especially if there are two extensions, can form a bearing fork for the gimbal bearing of the functional section relative to the coupling section. For the implementing the gimbal bearing it can be intended that a first pivoting element is mounted pivotable about a first pivoting axis relative to the two extensions. Such a first pivoting element can be formed by a frame element, for example. Such a frame element can, in turn, be pivotable and arranged between or around the two extensions. A second pivoting element can be arranged opposite the first pivoting element so that it can pivot about a second pivoting axis. The second pivoting axis is orthogonal to the first pivoting axis. The second pivoting element can be pin-shaped and can extend through the frame element. In particular, it may be intended that the second pivoting element is formed as a hollow pin in whose inner cavity, which is oriented in the axial direction, the toothed shaft extends. In other words, the toothed shaft can be enclosed by the second pivoting element.
It may be intended that the functional section comprises two plate-like elements. These plate-like elements can be connected by struts extending in axial direction. It may also be intended that the hone strips and/or the pneumatic measuring device and/or the rack-and-pinion gear are arranged entirely between the plate-like elements. The plate-like elements can form, in axial direction, a front and rear boundary of the functional section of the honing tool. The pneumatic measuring device can comprise measuring strips with measuring nozzles arranged thereon. A measuring strip can comprise one or more measuring nozzles. The measuring strips may be held in measuring strip holders, which, in turn, may extend at the above plate-like elements from a first of these plate-like elements to a second plate-like element. It is also conceivable that the hone strips extend from the first plate-like element to the second plate-like element. The extension of the hone strips or measuring strips is typically oriented in axial direction. In other words, it extends in an axial direction.
The pneumatic measuring device can comprise measuring strips which are held in measuring strip holders and on which measuring nozzles are arranged, wherein the radial position of the respective measuring strips can be adjustable in relation to the measuring strip holders. To this purpose, a positioning device is typically provided, which is configured to adjust the radial position of the measuring strips. This allows the honing tool to be easily adapted for machining different nominal diameters.
Such a positioning device can be implemented, for example, by a screw-based mounting of the measuring strips in relation to the measuring strip holder or of the measuring strip holder in relation to the functional section or its frame structure, in particular in relation to the plate-like elements of the frame structure.
The positioning device may be formed by a screw-based mounting of the measuring strips in relation to the functional section. In particular, the mounting of the measuring strips can comprise at least one first screw which is screwed into the functional section 12 and holds the measuring strip or the corresponding measuring strip holder from the radial outside. Furthermore, the positioning device may comprise a second screw which is screwed into the measuring strip or the corresponding measuring strip holder and abuts on the functional section such that the measuring strip can be moved radially outwards relative to the functional section by screwing the second screw into the measuring strip or the corresponding measuring strip holder. To this, the second screw can bear on the frame structure with its end facing away from the measuring strip, for example, and screwing the second screw into the measuring strip or the measuring strip holder thus causes the measuring strip or the measuring strip holder to be spaced apart from the functional section or its frame structure, in particular in relation to the plate-like element of the frame structure. Typically, the second screw can be formed as a headless threaded bolt.
At both axial ends of the measuring strips or measuring strip holders a respective positioning device may be arranged.
The hone strips and/or measuring strip holders can be detachably mounted to, in particular screwed on, the tool body. Typically, the measuring strips are formed such that the measuring nozzle is arranged, in axial direction, in the center of the measuring strip.
It may be intended that the measuring strip has at one axial end a connection for a pressure medium supply. This connection can lead into a pressure media channel extending in axial direction through the material of the measuring strip. The pressure media channel, which can extend through the material of the measuring strip, can directly lead into the measuring nozzle. Typically, the connection for the pressure medium is located at the spindle side end of the measuring strip.
It is also conceivable that a tube-like extension is attached to measuring strip holders and forms a supply for a pressure medium to the measuring nozzle. Typically, such a tube-like extension coming in axial direction from the honing spindle firstly extends in the axial direction and then has a bend so that it extends in the radial direction, and then leads into the measuring strip holders. The tubular extension can protrude into the material of the measuring strip holders.
A honing tool of one of the types described in this application is also a part of the invention, whereby the hone strips of the honing tool are formed according to one of the general types described in the following in connection with the figures and the claims.
A hone strip is also part of the present invention, in particular for use in an above described honing tool, with a support and at least one honing stone. In accordance with the invention, the support has a clamping device by means of which the at least one honing stone can be releasably clamped and fixed to the support in a clamping position of the clamping device. Such construction allows a reliable attachment of at least one honing stone to the support and at the same time a simple replacement of worn honing stones. For replacing a honing stone, only the clamping device has to be released without, for example, the need of separating adhesive or solder joints in an laborious way. This considerably facilitates the maintenance of a honing tool, thereby reducing non-productive times and thus operating costs. The support can be designed such that, when looking radially at the hone strip, it projects beyond the honing stone or honing stones in the circumferential direction and/or in the axial direction. The support can be virtually formed such that it forms a kind of frame for the honing stones, or in other words, that it surrounds the honing stones like a frame.
The clamping device may comprise at least one joining section and one clamping element. In particular, the joining section is fixedly arranged on the support. It is conceivable, for example, that the joining section is formed in one piece with the support. The joining section can be formed such that the at least one honing stone in the clamping position abuts on the joining section in the circumferential direction. In the clamping position, the clamping element can be arranged circumferentially on the opposite side of the honing stone, abut on it and urge it circumferentially against the joining section so that the honing stone is clamped and held between the joining section and the clamping element. It is particularly preferred that a contact between the joining section and the honing stone and/or a contact between the clamping element and the honing stone is possible along the entire axial extent of the honing stone. This enables secure fixation of the at least one honing stone to the support. In particular, slipping of the honing stone during machining of a workpiece is prevented, which is advantageous for high machining accuracy.
The clamping device may comprise a fixing element which is designed and arranged such that in the clamping position it abuts on the clamping element and urges the same towards the joining section. This makes it possible to provide a clamping effect to the at least one honing stone by applying a force to the fixing element. The fixing element can also be used for releasably fixing the clamping element to the support. It is conceivable, for example, that the fixing element is designed and arranged such that in the clamping position it additionally urges the clamping element towards the support, so that the clamping element is clamped and held between the fixing element and the support.
A contact surface between the joining section and the honing stone may be located in a plane which extends substantially in the axial and radial directions. It is also conceivable that a contact surface between the clamping element and honing stone lies in a plane that extends substantially in the axial and radial directions. Such configuration is advantageous in that the at least one honing stone, considered in a circumferential direction, is held between the joining section and the clamping element by form-fit. In this way, the forces transmitted to the honing stone in the circumferential direction during machining (e.g. frictional forces between honing stone and workpiece due to the rotary movement of the honing tool) can be safely transferred to the support. Slipping of the honing stone can thus be prevented, which contributes to a high precision during machining.
A contact surface between the fixing element and the clamping element may be located in a plane which extends in the axial direction and extends in a further direction which has an angle relative to the radial direction when looking at a plane extending orthogonally to the axial direction, wherein this angle is between 15° and 45°, in particular between 20° and 40°, in particular between 25° and 35°. This makes it possible to transfer a movement of the fixing element in the radial direction into movement of the clamping element in a circumferential direction (gear function).
The clamping element and the fixing element may be formed and arranged such that the fixing element urges the clamping element in the circumferential direction towards the honing stone when the fixing element moves in a radial direction, in particular radially inwards. A movement direction of the fixing element and a movement direction of the clamping element are therefore decoupled. This makes it possible to exert a clamping force on the at least one honing stone in the circumferential direction by applying a force to the fixing element in the radial direction.
The clamping device may also include a tensioning mechanism configured to move the fixing element, when transferring it into the clamping position, in a radial direction, in particular radially inwards. When the fixing element moves radially inwards, the at least one clamping element is preferably urged in the circumferential direction towards the honing stone, so that, in turn, the latter is urged towards the joining section. This makes it possible to exert a clamping effect on at least one honing stone via the clamping mechanism. The tensioning mechanism can also be used to secure the fixing element and/or the clamping element against loss.
The tensioning mechanism can, for example, be a screwed connection. It is possible, for example, that the fixing element can be detachably fastened to the support by means of one or more fastening screws and that when the at least one fastening screw is tightened, the fixing element is moved in the radial direction, in particular radially inwards. This ensures a particularly simple and reliable clamping of the at least one honing stone to the support. A configuration of the clamping mechanism as a screwed connection also has the advantage that a worn honing stone can be replaced particularly easily and with merely minor usage of tools. Merely the at least one fastening screw must be released, e.g. by means of a screwdriver, in order to remove a clamping effect of the clamping device.
According to a preferred embodiment, the hone strip may comprise two honing stones. In this case, the clamping device may comprise two circumferentially outer joining sections, two clamping elements arranged between the honing stones when viewed in the circumferential direction, and at least one fixing element arranged between the clamping elements when viewed in the circumferential direction.
Preferably the honing stones in the clamping position abut on one of the two outer joining sections. In the clamping position, the clamping elements preferably abut on a honing stone. The fixing element may preferably have a trapezoidal cross-section, in particular in the form of a symmetrical trapezium. Preferably, the two non-parallel leg surfaces of the trapezium form the contact surfaces to the clamping elements. This enables to strain both clamping elements simultaneously—in opposite directions—in the circumferential direction by straining one fixing element. This has the advantage that a clamping force of the same amount can be applied to both honing stones. Furthermore, in this way, a particularly quick and easy replacement of the two honing stones can be achieved, since merely one fixing element needs to be released to remove the clamping effect.
Further features, possibilities of application and advantages of the invention can be derived from the following description of embodiments of the invention, which are explained with reference to the drawings, wherein the features can be essential to the invention when considered singly or in various combinations, even if not explicitly pointed out again. The figures are showing:
In the following figures, corresponding components and elements have the same reference signs. For the sake of better clarity, not all reference signs are shown in all figures.
Coupling section 14 comprises a coupling flange 28, which is formed as a coupling plate 30 on the spindle side. From coupling plate 30 on the spindle side, two extensions 32 extend in an axial direction A into functional section 12. The two extensions 32 form a bearing fork 34 for a gimbal bearing of functional section 12 relative to coupling section 14.
In
In
Rack-and-pinion gear 44 with the section of toothed shaft 40 interacting with racks 42 and racks 42 itself are arranged between a first plate-like element 46 and a second plate-like element 48, when seen in axial direction A. The first plate-like element 46 forms the spindle side end of the functional section and the second plate-like element 48 forms the end of functional section 12 facing away from the spindle.
Hone strips 16 and measuring strip holders 20 each extend from first plate-like element 46 in the axial direction to second plate-like element 48 (see
Measuring strip holders 20 of the embodiment according to
The positioning device comprises a plurality of first screws 54 (two at the respective axial ends of the measuring strip holders 20, respectively), two of which are shown visibly in the sectional view of
First screws 54 abut with their respective heads 55 on measuring strip holders 20, and thus, hold measuring strips 22 from the radial outside. Measuring strip holders 20 are thus held radially outwards such that they cannot be lost in relation to plate-shaped elements 46, 48.
A second screw 56 is screwed into each of measuring strip holders 20 in the region of their axial ends. On the radially inner side, it protrudes from measuring strip holders 20 and abuts on the respective plate-shaped element 46, 48 (
As shown in
In the embodiment shown in
The structure of a hone strip 16 is explained in detail below with reference to
Each hone strip 16 has two honing stones 18, which preferably extend over the entire axial extension of the hone strip 16—from first plate-like element 46 to second plate-like element 48 of honing tool 10 (see
Hone strip 16 also comprises a support 76 for receiving honing stones 18. Preferably, support 76 extends along the entire axial extension of hone strip 16 (see
Support 76 also has a receiving region 86 on its front side 78 which is arranged approximately centrally with respect to the extension of support 76 in the circumferential direction U (see
Support 76 also has two receiving sections 90 on its front side 78 for receiving one honing stone 18, respectively (see
Support 76 is connected via a screwed connection 98 to a mounting body 96 at a rear side 94 facing honing tool 10 (see
Joining sections 80 are part of a clamping device 100, by means of which the two honing stones 18 can be detachably clamped and fixed to support 76 in a clamping position shown in
Clamping elements 102 each have an substantially trapezoidal cross-section in a section plane orthogonal to the axial direction. Accordingly, clamping elements 102 in their cross-section have two parallel surfaces (long base surface 104 and short base surface 106) and two surfaces oriented inclined with respect to parallel surfaces 104, 106 (first clamping surface 108 and second clamping surface 110, see
Clamping device 100 further comprises a fixing element 112 which preferably extends along the entire axial extension of the honing stones 18 (see
In the clamping position, clamping elements 102 are each arranged on the side of the assigned honing stone 18 opposite the respective joining section 80, when seen in the circumferential direction U. Clamping elements 102 are thus arranged between the two honing stones 18, when seen in the circumferential direction U. Each clamping element 102 abuts with its long base surface 104 on bottom surface 88 of central receiving region 86. Clamping elements 102 are oriented such that second clamping surfaces 110 of clamping elements 102 face each other. Each clamping element 102 with its respective first clamping surface 108 abuts on a respective third side surface 126 of the honing stone 18 assigned to it. A contact surface 128 between honing stone 18 and clamping element 102 extends in axial direction (in
Fixing element 112 is arranged between clamping elements 102 in the circumferential direction and is oriented such that short base surface 114 faces support 76. Fixing element 112 abuts with its leg surfaces 118 on second clamping surfaces 110 of clamping elements 102. A contact surface 130 between fixing member 112 and the respective clamping member 102 extends in axial direction (in
Clamping device 100 further comprises a tensioning mechanism 136 by means of which fixing element 112—for transferring clamping device 100 into the clamping position—can be moved in the radial direction, in particular radially inwards (opposite to the arrow marked “R” in
When fixing screws 138 are tightened, fixing element 112 is moved radially inwards, i.e. towards support 76 (opposite to the arrow marked “R”). Fixing element 112 slides with its leg surfaces 118 along second clamping surfaces 110 of clamping elements 102, which extend parallel to leg surfaces 118. Since contact surfaces 130 between fixing element 112 and clamping elements 102 are inclined relative to the radial direction R, clamping elements 102—when fixing element 112 moves radially inwards—are each strained in the circumferential direction U outwards (in opposite directions). Thereby, clamping elements 102 with their respective first clamping surfaces 108 urge the respective honing stone 18 against the respective joining section 80. In this way, a clamping effect is achieved.
In the clamping position, honing stones 18 are clamped between respective section 80 and respective clamping element 102 assigned to them. The respective clamping element 102 is, in turn, clamped between the respective honing stone 18, bottom surface 88 and fixing element 112. Fixing element 112 is, in turn, held to support 76 in a lost-proof manner by fastening screws 138.
To remove the clamping effect of clamping device 100—e.g. for replacing a worn honing stone—merely fastening screws 138 must be released. A complete dismounting of fixing element 112 from support 76 is preferably not necessary for replacing honing stones 18.
With embodiments not depicted, a kinematic reversion may also be possible in the sense of the invention, in which a movement of fixing element 112 radially outwards (in the direction of the arrow marked “R”) leads to a movement of clamping elements 102 in the circumferential direction towards the respective honing stone 18. For example, it is conceivable that clamping elements 102 and fixing element 112 are arranged mirrored with respect to a plane orthogonal to the radial direction, and a tensioning mechanism 136 comprises one or more pressing screws which engage in corresponding threaded radial holes of the fixing element and bear with an end head on bottom surface 88 of central receiving region 86. In this way, when the pressing screws are tightened, fixing element 112 can be moved radially outwards.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102018123145.8 | Sep 2018 | DE | national |
