Patent Application
20200368872
The present invention relates to a centerless cylindrical grinding machine for throughfeed and plunge grinding of arbitrary workpieces according to the preamble of claim 1, as this is described, for example, in EP 1 330 336. Instead of the terms throughfeed and plunge grinding, other terms, like throughput or longitudinal grinding or transverse grinding are also used in the literature.
Centerless cylindrical grinding machines differ from other cylindrical grinding methods in that the workpiece to be processed is not frictionally clamped in the machine or a device, but instead rests loosely on a support (workpiece support). The centerless grinding enables a higher production accuracy and a higher productivity with respect to other cylindrical grinding methods.
Common designs for centerless cylindrical grinding machines generally have a grinding headstock with a grinding wheel driven in an axis (XS) and a regulating wheel headstock with a regulating wheel likewise driven in an axis (XR). A workpiece support or a support plate functioning for this purpose is securely fixed to the machine bed between the two headstocks. Dressing devices for the grinding headstock and the regulating wheel headstock are generally mounted outside and are movable relative to the respective headstocks via additional driven axes (X′ and Y′ and also X″ and Y″). These designs have the disadvantage that a large number—up to six—driven positioning axes are present, which makes these machines very expensive.
In contrast, EP 1 330 336 proposes a centerless cylindrical grinding machine with only three positioning axes. This is, in the case of the described centerless cylindrical grinding machine with driven positioning axes XS (or US) and XR for adjusting the grinding headstock and the regulating wheel headstock and another driven positioning axis YW, extending orthogonal to the axis XR, for a carriage with a workpiece support on a carriage track, facilitated by the carriage being movable on the carriage track into a position lying outside of a safety housing and the carriage being selectively equipped with a dressing device acting internally or externally.
Regardless of the number of positioning axes, however, it is common in the known centerless cylindrical grinding machines from the prior art that the area of the machine bed, in which the actual processing of a workpiece takes place, is spaced at a distance for access across the area of the machine bed into which the carriage track projects; thus the area of the machine bed, into which the carriage track projects, must be crossed for access. A change of the grinding wheel and/or regulating wheel, also access to components located in this area, is thereby made generally more difficult. However, a lateral access to the area of the machine bed, into which the carriage way projects, is also likewise hindered by the scope of the extension, so that access is substantially limited to a frontal intervention regardless of other spatial constraints.
It is the object of the present invention, starting from this prior art, to accordingly further develop a centerless cylindrical grinding machine so that the accessibility is improved to the area of the machine bed, in which the grinding headstock and the regulating wheel headstock are arranged, and to the area of the machine bed, in which the carriage track projects or is at least partially arranged.
This problem is solved by the features of claim 1. Additional advantageous configurations of the invention arise from the dependent claims.
According to the invention, a generic centerless cylindrical grinding machine is provided for throughfeed and plunge grinding of arbitrary workpieces comprising a first drivable positioning axis XS for a grinding headstock with a grinding wheel rotatable about an axis of rotation and a second drivable positioning axis XR for a regulating wheel headstock with a regulating wheel rotatable about an axis of rotation, and a workpiece support arrangeable substantially between the grinding headstock and the regulating wheel headstock, wherein further drivable positioning axis YW, extending orthogonal to at least one of the positioning axes XS and XR, is mounted for a carriage on a carriage track, via which the workpiece support is movable, wherein the grinding headstock and the regulating wheel headstock are arranged in a first area of a machine bed and the carriage track is at least partially arranged in a second area of the machine bed, and the second area of the machine bed has a lesser extension in a direction parallel to the positioning axis YW than the first area of the machine bed.
The positioning axis XS and the positioning axis XR extend in many cases parallel to one another, wherein the axis of rotation of the grinding wheel and the axis of rotation of the regulating wheel are each arranged orthogonal to the respective positioning axes XS and XR. Alternatively to this, the positioning axis XS may, however, also be arranged inclined with respect to positioning axis XR. Due to this inclination and the respective deviation to a coordinate direction associated with “X”, the positioning axis may also be designated as positioning axis US for better differentiation. However, for simplification, both alignments are subsumed under positioning axis XS. In the case of the inclination of positioning axis XS with respect to positioning axis XR, the axis of rotation of the grinding wheel may be arranged orthogonal to the positioning axis XS, which, however, is not mandatory. The positioning axis YW is, however, in such a case, arranged orthogonal to one of the positioning axes XS or XR, preferably to positioning axis XR.
A fundamental advantage is that at least one free space results from the lesser extension of the second area of the machine bed, due to which, for example, a better access is facilitated for an operator. In other words, a projection is formed as the second area of the machine bed, starting from the first area of the machine bed in the direction of the positioning axis YW.
The carriage track may be located solely in this second area of the machine bed, if the carriage, mounted on said carriage track, with the workpiece support provided for the processing, projects sufficiently past the same into the processing area formed between the grinding wheel and the regulating wheel in an end-of-travel position. Alternatively, however, the carriage track may also extend into the second area of the machine bed, in order to extend the potential travel path, in particular if the carriage, mounted on said carriage track, with the workpiece support or the workpiece located on the workpiece support does not project past the carriage track. In this case, however, the carriage track extends at least partially, i.e. with the end facing away from the processing area, into the second area of the machine bed.
Preferably, free spaces are formed by the lesser extension on both sides of the second area of the machine bed adjacent to the first area of the machine bed. Due to free spaces on both sides, accessibility is increased, in particular with respect to the grinding wheel and the regulating wheel.
Preferably, the second area of the machine bed extends, starting from the first area of the machine bed, in a direction parallel to the positioning axis YW at least over a length of the workpiece support in this direction. The length of the carriage track extending in the second area of the machine bed in the direction of the positioning axis YW, and thus the minimum length of the second area of the machine bed in this direction, thus corresponds at least to the length, by which the workpiece support may be moved completely out of the processing area. Workpieces may thus be removed and positioned again on the workpiece support without an intervention into the processing area.
In one configuration of the invention, the extension of the second area of the machine bed is substantially symmetrically parallel to at least one of the positioning axes XS and XR, with respect to a center axis of the carriage track parallel to the positioning axis YW. By this means, a balanced access is facilitated on both sides. The accessibility equally present on both sides increases the flexibility of the machine installation with respect to given spatial situations and may offer ergonomic advantages with respect to the operating personnel, as an advantageous side for operation, for example, by left- or right-handed people, may be selected for access, depending on the person. The expression “substantially symmetrical” thereby relates to the basic form of the second area of the machine bed, wherein small contour deviations, for example, a projection or an undercut formed by a switching panel, are negligible with respect to the access from both sides.
Preferably, the centerless cylindrical grinding machine comprises a movable, in particular pivotable, operating panel, which is movable from one side of the second area of the machine bed extending parallel to positioning axis YW to the respective other side. By this means, it is possible that the operating panel is flexibly arrangeable. The operating panel may thereby be moved to the side of the operator. If no operations are intended via the operating panel, the operator may move the panel, for example, out of a field of action, in order to not be disturbed by the operating panel.
In an embodiment of the invention, the centerless cylindrical grinding machine has a first cover which is movable from a loading position into a protection position and, in the protection position, at least partially encompasses the second area of the machine bed, starting from the first area of the machine bed.
In a loading position, the first cover is located in a position, in which the cover releases the second area of the machine bed for positioning a workpiece on the workpiece support or at least expands the potential for access with respect to a protection position. The loading position is not limited to its use for the positioning of workpieces on the workpiece support, but may also be used for removing the workpieces or to access components in the first area of the machine bed. In contrast to the loading position, access to the second area of the machine bed is limited or completely prevented in a protection position of the first cover.
The cover does not have to be designed as continuous, but instead may be formed from individual cover sections. The potential thereby exists to limit the material expense in that the cover sections are provided, for example, only in critical safety zones. The cover sections or the first cover as a whole may also have a grid or cage-like characteristic. Individual cover sections may preferably be moved independently of one another into a loading or protection position. The movement of the first cover or individual cover sections may be carried out manually or driven, in particular automatically depending on the process state, for example, automatic movement of the first cover into a loading position, after the workpiece support has moved out of the processing area into the second area of the machine bed.
In particular, the first cover is movable perpendicular to the surface formed by the second area of the machine bed. The first cover may be guided in a space saving way in the direction of the side walls adjoining the machine bed and oriented towards the floor. The first cover is particularly preferably guided inwardly with respect to the side walls, i.e. configured to be at least partially retractable into the same. The first cover may be protected by this means. In addition, the side wall also functions for protecting the operator by minimizing moving components in direct contact areas, and thus the risk of collision or being pulled in.
In one configuration, the first cover is at least partially open in the protection position on a side facing away from the second area of the machine bed. In other words, an opening area is formed opposite the surface formed by the second area of the machine bed. The design of the first cover may thus be simplified. However, the opening area also offers access potentials, even in the case of a movement blocking of the first cover, which may be used, for example, in such a case for repair work. The opening area is, however, preferably to be located in a position, for example at a sufficient height, in order to at least make access to the areas of risk more difficult, or to prevent such access according to conventional criteria.
Preferably, the first cover is at least partially transparent at least in sections. By this means, it is possible to view at least partial areas of the second area of the machine bed, and thus to make a visual inspection available, and/or to use optical components for monitoring, documentation, or the like, which are likewise protected by the first cover.
In an embodiment, the centerless cylindrical grinding machine has a detection unit, which, in a protection position of the first cover, detects whether a protection area is accessed. A corresponding detection signal may be used to generate a warning signal and/or to stop the machine in order to counter a risk situation. The protection area monitored by the detection unit may be smaller than the area formed by the cover in the protection position. For example, the first cover may have a height, due to which access to a lower-lying area of risk is better prevented. The protection area monitored by the detection unit is limited in this example merely to the lower-lying area of risk, by way of example. The reaction to the detection signal may also vary, depending on the establishment of threshold values, so that, for example, when using a distance sensor, an acoustic and/or visual warning signal is initially emitted in the presence of a detection signal, and the machine is stopped upon falling below a critical distance.
In an embodiment, the centerless cylindrical grinding machine comprises a 3D detection unit, which covers at least the area of the protection position of the machine bed. As soon as an object enters the scanning area, a warning signal is generated and/or the machine is stopped to counter a risk situation.
Preferably, in the loading position, the first cover does not project substantially over the workpiece support. A largely free access is facilitated to the workpiece support by this means. The expression “substantially” is accordingly to be understood that no interference contours, which influence the ergonomics of the operator or direct access by handling components, like gripping arms, are formed by the first cover in the loading position for the loading or removal of workpieces.
Preferably, the centerless cylindrical grinding machine comprises a second cover, which is movable from an access position into a protection position, and which at least partially encompasses the first area of the machine bed. In the access position, the components arranged in the first area of the machine bed, like the grinding headstock and the regulating wheel headstock, are accessible, as this is necessary, for example, for exchanging the grinding wheel or the regulating wheel. The protection position of the second cover prevents or at least limits access to areas, from which a risk situation arises.
In particular, the first area of the machine bed is completely closed to an access from outside by the second cover in the protection position. In one variant, an opening remains in the second cover in the protection position in the area of the transition between the first area of the machine bed and the second area of the machine bed, the opening facilitates the movement of the carriage or the workpiece support, respectively, into and out of the processing area or from the first area into the second area, respectively, and vice versa. The opening is preferably as small as possible, thus in particular adapted to the dimensions of the workpieces on the workpiece surface located on the carriage, which are movable through the opening, in order to prevent other interventions or to at least reduce corresponding possibilities.
In an embodiment of the invention, the second cover is foldable. A simple and robust design of the second cover is thereby facilitated.
The first and the second covers do not have to be designed as separate covers. Alternatively, the first cover may form a part of the second cover or vice versa. Embodiments of the first cover with the previously mentioned advantages are correspondingly transferrable to the second cover, regardless of the spatial assignment of the covers, and vice versa.
In one embodiment of the invention, the second area of the machine bed is movable into the first area of the machine bed. The length of the projection formed by the second area of the machine bed may thus be adjusted. An unused length, for example, due to a shortened travel path of the carriage for processing or due to non-use of the machine or at least of the second area of the machine bed may thus be used to provide a free area. A movement possibility of the second area of the machine bed through the first area for the positionally-dependent forming of a projection on both sides may allow equipping from both sides.
Features and functionalities of the invention are also subsequently described by way of exemplary embodiments with reference to the drawings.
It is shown:
The figures each show the components essential for the described facts. For the benefit of simplicity, components that have otherwise already shown are not necessarily depicted again, even if these are comprised or at least may be comprised by a centerless cylindrical grinding machine.
The centerless cylindrical grinding machine 100 according to
The grinding headstock 10, the regulating wheel headstock 20, and the carriage 31 on the carriage track 30 are preferably installed on a machine bed 40, preferably made from thermostable natural granite. The grinding headstock 10 and the regulating wheel headstock 20 are thereby arranged in a first area 41 of machine bed 40, while the carriage track 30 projects at least partially into a second area 42 of machine bed 40. The first area 41 and the second area 42 of the machine bed 40 are distinguishable in that the second area 42 of the machine bed 40 has a lesser extension in a direction parallel to positioning axis YW than the first area 41 of the machine bed 40. In other words, the second area 42 of the machine bed 40 forms a projection, starting from the first area 41 of the machine bed 40 and extending in the direction of positioning axis YW. In comparison with a centerless cylindrical grinding machine with a uniformly-wide machine bed, due to the second area 42 of machine bed 40, depicted in
In the configuration shown in
Due to the symmetrical extension of the second area 42 of the machine bed 40, with respect to the center axis 33 of the carriage track 30 in the direction parallel to the positioning axes XS and XR, equally good accessibility results from the two sides, so that an operator may freely chose a position in relation to a preferred direction for operating or access.
The arrangement of a movable operating panel 50, shown in
In a configuration of a first cover 60 according to
In addition to the first cover 60, a second cover 70 is also provided in
The second cover 70 is shown here in a protection position and is designed to be foldable about the first pivot axis 71 and the second pivot axis 72. In this position, the second cover 60 encompasses the grinding headstock 10 with the grinding wheel 11 and the regulating wheel headstock 20 with the regulating wheel 21 in the first area 41 of the machine bed 40 from two sides, perpendicular to the surface formed by the machine bed 40, which extend parallel to the positioning axes XS and XR, and a surface formed between these sides on a side facing away from the first area 41. Sections of the second cover 70 may also be formed by other system components, for example, a rear wall at the side of the first area 41 of the machine bed 40 facing away from the second area 42.
The second cover 70 has also provides an opening 73 on the side surface facing the second area 42 of the machine bed. The carriage 31 and the workpiece support 32 including a workpiece may also be moved through the opening 73 between the first area 41 and the second area 42 of the machine bed 40 when the second cover is located in a protection position. The opening 73 may be closeable so that the opening 73 is only open for the movement of the carriage or of the workpiece support through the same.
The invention is not limited to the described embodiments. Even if the projection is shown here as a rectangle, the transition may have radii, taper, etc. Alternatively to the use of a pivot arm pivotable about a pivot axis, the operating panel may be moved in a guide along the machine bed. When providing a pivot arm, the pivot arm may also be designed as originating from above.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19175307.8 | May 2019 | EP | regional |
