Abstract
A clamping device (1) for holding a workpiece (10), in particular a cutting tool, during machining in a grinding machine, wherein peripheral grinding of the workpiece (10) is performed by means of a particularly approximately cup-shaped grinding wheel, wherein the clamping device (1) comprises a support unit (40) provided to be mounted on the grinding machine, a clamping unit (20) comprising a clamping anvil (12) supported in a clamping anvil holding element (22) and translationally drivable to apply a clamping force parallel to a clamping axis (16), and a drive unit (30) comprising a drive anvil (14) supported in a drive axis (18) and rotationally drivable for rotary orientating the workpiece (10) by means of the drive axis (18). The clamping unit (20) and the drive unit (30) are provided as individual components, which are releasably or slidably attached to the support unit (40) to form a workpiece spindle headstock of the grinding machine.
Claims
1. A clamping device for holding a workpiece during machining in a grinding machine, wherein peripheral grinding of the workpiece is performed by means of a particularly approximately cup-shaped grinding wheel, wherein the clamping device comprises: a support unit adapted to be mounted on the grinding machine, a clamping unit comprising a clamping anvil supported in a clamping anvil holding element and translationally drivable to apply a clamping force parallel to a clamping axis, and a drive unit comprising a drive anvil supported in a drive axis and rotationally drivable for rotary orientating the workpiece by means of the drive axis, wherein the clamping unit and the drive unit are provided as individual components, which are releasably or slidably attached to the support unit to form a workpiece spindle headstock of the grinding machine.
2. The clamping device according to claim 1, wherein the support unit provides a guidance to slidably attach at least one of the clamping unit and the drive unit and means to securely fix the clamping unit and/or the drive unit at a predetermined position, such that a clearance between the clamping unit and the drive unit is adjustable in a longitudinal direction of the clamping axis.
3. The clamping device according to claim 1, wherein the support unit has an L-shape with one leg perpendicularly protruding from a supporting surface, wherein in said one leg a bore is provided for supporting the clamping unit or the drive unit and the other of the clamping unit and the drive unit is releasably attached to the supporting surface of the support unit.
4. The clamping device according to claim 3, wherein the support unit comprises positioning means and fastening means at an interface for releasably attaching at least one of the clamping unit and the drive unit.
5. The clamping device according to claim 4, wherein the positioning means are configured as guide pins protruding at predetermined positions from the support unit and which guide pins are adapted to be received in corresponding guide bushes provided on a contact surface on one of the clamping unit and the drive unit, in order that said camping unit or drive unit can be releasably attached to the support unit.
6. The clamping device according to claim 5, wherein the guide pins are formed as circularly cylindrical bodies and the guide bushes are formed by roll bodies held in a cage, wherein the roll bodies can be balls or sliders.
7. The clamping device according to claim 4, wherein the fastening means can be provided as bayonet catch, snap lock or threaded lock.
8. The clamping device according to claim 1, wherein the clamping device comprises an actuating unit with an actuating rod for generating the clamping force and transmission means for transmitting the clamping force to the clamping anvil.
9. The clamping device according to claim 8, wherein the actuating unit is integrally arranged in the clamping unit and is provided as a pneumatic, hydraulic or electromagnetic cylinder unit.
10. The clamping device according to claim 8, wherein the transmission means comprises a lever device for transmitting the force generated by the actuating unit to the clamping anvil of the clamping device.
11. The clamping device according to claim 10, wherein the lever device comprises a first arm adapted to be inexchangeably mounted in the clamping unit and a second arm adapted to be exchangeably mounted in the clamping unit, the first arm and the second arm being releasably connected to each other.
12. The clamping device according to claim 1, wherein measuring means are provided to measure geometries of the workpiece to be held in a clamped position by the clamping device.
13. The clamping device according to claim 12, wherein the measuring means comprise a measuring lever being in contact to a measuring head which can be actuated by the measuring lever.
14. The clamping device according to claim 13, wherein the measuring lever of the measuring means is arranged in the clamping unit and is provided to actuate the measuring head arranged in the support unit.
15. A grinding machine for peripheral grinding a workpiece by a cup-shaped grinding wheel, wherein the workpiece is clamped in position by the clamping device according to claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Preferred embodiments of the invention are now described in more detail with reference to the enclosed drawings, given by way of non-limiting example, wherein:
[0037] FIG. 1 shows a schematic side view of a clamping device of a first embodiment;
[0038] FIG. 2 shows a schematic sectional view of the clamping device of the first embodiment;
[0039] FIG. 3 shows an at least partially exploded perspective view of the clamping device of the first embodiment;
[0040] FIG. 4 shows a schematic side view of a clamping device of a second embodiment;
[0041] FIG. 5 shows a schematic sectional view of the clamping device of the second embodiment;
[0042] FIG. 6 shows an at least partially exploded perspective view of the clamping device of the second embodiment;
[0043] FIG. 7 shows a partially exploded perspective view of a clamping device of a third embodiment.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0044] In the different figures of this invention and its part, like details are indicated by like reference numbers throughout the figures and its specification. The reference number 1 indicates a clamping device according to the invention in its entirety.
[0045] FIG. 1 shows a schematic side view of a clamping device 1 designed as a part of a grinding machine, in particular comprising a cup-shaped grinding wheel to machine a workpiece 10, such as a cutting tool clamped in the clamping device 1. A rotary plate 2 on a machine bed can be moved in a direction of a first rotational axis, identified as a C-axis (not shown). Furthermore, the clamping device 1 can be pivoted about a B-axis 18. Thanks to a pivoting movement by rotating the clamping device 1 about a A-axis (not shown), perpendicular to the B-axis 18 and thanks to translational and/or rotational movements of the grinding wheel about at least the X-axis and an Y-axis (not shown) the peripheral surface of the clamped workpiece 10 can be theoretically ground. The rotary plate 2 of the grinding machine bears a workpiece spindle headstock comprising inter alia the clamping device 1.
[0046] The workpiece 10, such as a cutting tool, in particular an indexable insert to be ground can be affixed to, centered and securely clamped on the clamping device 1, in particular between a clamping anvil 12 and a drive anvil 14. The clamping anvil 12 is supported in a clamping device holding element 22 of a clamping unit 20 and movable in translation along a clamping axis, identified as 16 to apply a clamping force. The drive anvil 14 is supported in a drive unit 30 and is connectable to a drive axis, the B-axis 18, of the grinding machine. Thus, during grinding the workpiece 10 can be rotated about the B-axis 18.
[0047] Not shown in FIG. 1, arranged at a distance from the rotary plate 2 does a grinding spindle headstock comprise inter alia a cup-shaped grinding wheel, wherein the grinding spindle headstock can be pivoted and moved relative to the rotary plate 2. Therefore, in the grinding machine for performing grinding of the workpiece 10 a plurality of controlled movements are mutually coordinated with one another.
[0048] According to a first embodiment of the clamping unit 1, the workpiece spindle headstock comprises the drive unit 30 and a support unit 40, which are not shown in further details. According to the FIG. 1, the support unit 40 is designed in L-shape with one portion, protruding substantially perpendicular from a support plate 39 and identified as a first leg 42. In the first leg 42, a bore is provided, configured as a bearing bore, such that an axis of the bore is aligned coaxially with the clamping axis 16 and extend parallel to a longitudinal extension of the support plate 39. In the bore of the first leg 42, the drive unit 30 is rotatably mounted consisting of the drive anvil 14, comprising a drive shaft 32 and an interchangeable drive pin 34. The drive shaft 32 can be inserted with a drive cone into a receiving cone of the B-axis 18, wherein the B-axis 18 can be rigidly supported by a B-axis bearing of the drive holding element 30 to provide very exact concentricity. The workpiece 10 can be fixedly mounted on the drive pin 34 by connection means.
[0049] According to the first embodiment, shown in FIG. 1 as a counterpart of the drive anvil 14 the clamping anvil 12 is provided, supported in the clamping unit 20 such that it is guided free of play axially and rotationally freely movable. The workpiece 10, in particular the indexable insert can be clamped between the drive anvil 14 and the clamping anvil 12 by arranging the workpiece 10 centered on the B-axis 18 and the clamping anvil 12 is moved by force against the drive anvil 14, arranged as a counter ram. According to the first embodiment, the clamping unit 20 is a separate or individual part, which can be releasably or slidably attached the support unit 40 to form the workpiece spindle headstock of the grinding machine. The clamping unit 20 is mounted to the support unit 40 in such a manner, that the axis of the clamping anvil 12 and the drive anvil 14 are aligned to each other and aligned with the clamping axis 16. For this purpose, the support unit 40 can provide on a contact surface 50 with positioning means 60 (not shown in FIG. 1).
[0050] The clamping force provided by the clamping unit 20 can be introduced in various manner, for example can be carried out by an actuating device (not shown in FIG. 1). The actuating device can comprise a power source, like a pneumatic or hydraulic cylinder unit, such that the movement of an actuating rod is transmitted via transmission means to the clamping device 1, in particular to the clamping anvil 12. Further details of the transmission means will be described later.
[0051] Furthermore, to provide sealing of the clamping unit 20 towards the environment a cover element 70 is releasably attached to the clamping unit 20. Depending on the design and/or material of the cover element 70, the attachable cover element 70 can contribute to increase the stiffness of the clamping unit 20 and finally of the clamping device 1.
[0052] In FIG. 2, a sectional schematic view of the clamping device 1 of the first embodiment is shown. As shown the drive anvil 14 and the clamping anvil 12 can be designed as being interchangeable. In FIG. 2 the clamping anvil 12 as well as the clamping unit 20 and the drive anvil 14 are designed in a so-called short version. With this short version, the space between the clamping unit 20 and the drive unit 30 is small such that the construction of the clamping device 1 is compact and stiff. With this design of the clamping device 1, the grinding machine offers an increased stiffness and is in particular suitable to perform high-speed grinding operations on the workpiece 10 clamped by the clamping unit 1.
[0053] Furthermore, for applying a clamping force transmission means are provided inter alia comprising a lever unit 100, described in further detail according to FIG. 5.
[0054] FIG. 3 shows a perspective view of the clamping device 1 according to the first embodiment, wherein elements such as the support unit 40 and the clamping unit 20 as well as the cover element 70 are shown separated to one another. The support unit 40 is formed in L-shape with the first leg 42 to support the drive unit 30. According to the first embodiment of the clamping device 1, the clamping unit 20 is provided as an individual element such that the workpiece spindle headstock can be described as an assembly or a mounted group. The clamping unit 20 is supported in the clamping holding element 22, wherein the clamping holding element 22 provides a contact surface 24, which is orientated towards a supporting surface 41 of the support unit 40. In order to position the releasable clamping unit 20 to the supporting surface 41 of the support unit 40 an interface 43 is provided with positioning means such as guide pins 44 protruding at predetermined positions from the interface 43 of the support unit 40. The guide pins 44 led (i.e. received) in corresponding guide bushes 45 (not shown) provided on the contact surface 24 of the clamping unit 20. This arrangement can be as well vice versa. The guide pins 44 can be formed as circularly cylindrical bodies. Further forms such as prism are as well possible. The guide bushes 45 can be formed by roll bodies, held in a cage, wherein the roll bodies can be balls, rollers or sliders. Furthermore, for fastening the clamping unit 20 to the support unit 20, fastening means 46 can be provided.
[0055] The clamping unit 1 of the invention comprises measurement means to detect in particular the thickness of the workpiece 10 clamped in a secured manner between the clamping anvil 12 and the drive anvil 14. Therefore, a measurement device 80 is provided comprising a measurement probe 83, whereby the measuring means 80 are connectable with the clamping unit 20, which in this embodiment is the releasably attached to the support unit 40. The measuring means 80 comprise a measuring lever 81 and a measuring head 82. The contact of the measuring lever 81 with the measuring head 82 or measuring probe can be configured in a prestressed manner by a spring element. For example, the contact between the measuring lever 81 and the measuring head 82 can be designed as between balls, between ball and plane, between rolls and/or roll and plane, etc. Furthermore, the measuring head 82 and the measuring probe 83 do not need direct contact for measuring but can be provided for optical measuring. Different materials are applicable for the elements in contact such as hardened steel, ceramic, sapphire or carbide.
[0056] In FIG. 4, a schematic side view of the clamping device 1 according to a second embodiment is shown. The second embodiment of the clamping device 1 shows a so-called long version of it. In particular, the clamping unit 20 shows another design and the drive anvil 14 and/or the clamping anvil 12 protrude further out of their bearings such that a clearance between the drive unit 30 and the clamping unit 20 is larger than provided as in the short version according to the first embodiment. In this long version of the clamping device 1, not only the drive anvil 14 and the clamping anvil 12 are designed with a long longitudinal extension but also the design of clamping unit 20 itself differs from that of the short version. In other words, the free space on both sides of the clamped workpiece 10 is increased for its positioning towards the cup-shaped grinding wheel. To provide stiffness to the configuration in this long version the clamping unit 20 differs from the short version of the clamping unit 20 according to FIGS. 1 to 3.
[0057] FIG. 5 shows a sectional view of the clamping device 1 according to the second embodiment. To transmit an actuating force of an actuating unit 92 such as an actuating cylinder unit, supported in the support unit 40 of the clamping device 1, transmission means 90 are provided such that a clamping force can be provided by the clamping unit 20 for securely clamping the workpiece 10 between the clamping anvil 12 and the drive anvil 14. The actuating unit 92 comprises an actuating rod (not shown in detail) which is axially displaceable, acted upon a spring force and which is connected to the clamping unit 20 via a lever device 100. Alternatively, the actuating unit 92 can be configured as a double-acting cylinder. The lever device 100 comprises a first arm 102 and a second arm 104 releasably connected to the first arm. The first arm pivots around a shaft 106, pivoted in a bearing member provided at the support unit 40 of the clamping device 1. The second arm 104 is connectable to the clamping anvil 12 such that the clamping anvil 12 moves axially to the clamping axis as a response to the pivot movement of the first arm 102 and therefore as a response of the actuation of the actuating unit 92. According to the design of the lever device, the first arm 102 is arranged such to remain in the support unit 40 and the second arm 104 is arranged such to be interchangeable. Due to this, the lever unit 100 can be adapted to the version of the clamping unit 20, in particular to the short version of the clamping unit 20 of FIGS. 1 to 3 or to the long version of the clamping unit 20 of FIGS. 4 to 6.
[0058] In FIG. 6, a perspective view of the clamping device 1 according to the second embodiment, wherein elements such as the support unit 40 and the clamping unit 20 as well as the cover element 70 are shown separated to one another is shown. The clamping unit 20 provides the contact surface 24 for mounting the clamping unit 20 to the support unit 40, in particular to the supporting surface 41. Therefore, the supporting surface 41 and/or the contact surface 24 are provided with guide means 50 corresponding to each other. Furthermore, the interface 43 of the support unit 40 for positioning and mounting the clamping unit 20 is provided as already described in accordance with FIG. 3.
[0059] FIG. 7 shows a partially exploded view of the clamping device 1 of a third embodiment. According to the third embodiment the drive unit 30, the clamping unit 20 and the support unit 40 are provided as individual elements, which can be releasably mounted to each other. In this embodiment the support unit 40 can be provided with linear guide elements such that the drive unit 30 and/or the clamping unit 20 can be slidable towards each other in a direction parallel to the clamping axis 16 and can be securely fixed in a position adjusted to the clearance between the drive unit 30 and the clamping unit 20 necessary for grinding the workpiece 10 with a cup-shaped grinding wheel at every surface to be machined.
[0060] Although the present disclosure has been described with reference to particular means, materials and embodiments, one skilled in the art can easily ascertain from the foregoing description the essential characteristics of the present disclosure, while various changes and modifications may be made to adapt the various uses and characteristics as set forth in the following claims.
