Gripping device in workpiece grinding apparatus

Abstract

[Problem] To configure a gripping device constituting a workpiece grinding apparatus so as to have a structure that enables stable and reliable gripping of a workpiece having an end face in an irregular three-dimensional shape. [Solution] Of a pair of clamping sections 4, 5 that constitute a gripping device 3, one clamping section 4 (or 5) is, as a follower clamping section, fitted with a plurality of gripping elements 41 that are independent of each other. The plurality of gripping elements 41 are housed in the follower clamping section 4 (5) interior in a way that allows said elements to pop out from / sink back into the end face of the follower clamping section 4 (5) independently of each other. When a workpiece 12 is gripped axially between the follower clamping section and the end face of the other clamping section 5 (4), axially directed tip-end faces of all the gripping elements 41 grip the workpiece 12 together with the end face of the other clamping section 5 (4).

Description

Grinding device for workpiece grinding equipment

[0001] The present invention relates to a gripping device in a workpiece grinding machine that enables grinding of the peripheral surface of a workpiece having a non-flat end surface on one axial side while stably gripping the workpiece.

[0002] When grinding or polishing the peripheral surface of a workpiece such as an ingot whose surface is to be finished into a cylindrical shape, the axis of the workpiece may not coincide with the axis of the clamping parts when the pair of clamping parts grip the workpiece in the axial direction. To cope with such a case, the pair of clamping parts may be designed to be able to adjust the angle relative to the workpiece when gripping the workpiece so that the axes of the workpiece and the clamping parts can be aligned (see Patent Documents 1 to 3).

[0003] In principle, the workpiece is assumed to be formed into a cylindrical shape with both axial end faces having planes perpendicular to the axis (paragraph 0032 of Patent Document 3), but since the end faces of the workpiece may be inclined with respect to the axis (paragraph 0015 of Patent Document 1), adjusting the angle of the pair of clamping parts relative to the workpiece also corresponds to irregularities in the workpiece itself.

[0004] However, supporting each clamping part on the spindle so that the angle can be adjusted freely with respect to the axis of the spindle that supports it means that when a workpiece is processed, such as by grinding, with the pair of clamping parts holding the workpiece, the clamping parts may be displaced with respect to the spindle. In this case, the stability of the workpiece when supported may be lost, which may reduce the accuracy of grinding, etc.

[0005] It is thought that the stability of the clamping parts when holding the workpiece can be ensured by increasing the pressure between the pair of clamping parts holding the workpiece. However, there is a possibility that excessive axial compressive force will be applied to the workpiece, which may cause minute distortions in the direction perpendicular to the axial direction of the workpiece during grinding. If distortions occur in the workpiece during grinding, it will also affect the grinding accuracy.

[0006] JP-A-11-207505 (paragraphs 0008 to 0017, Figures 3 to 5) JP-A-2022-50851 (paragraphs 0036 to 0037, 0059 to 0069, Figures 3, 9, and 10) JP-A-2023-69261 (paragraphs 0036 to 0047, Figures 3 to 5)

[0007] On the other hand, when a silicon carbide single crystal (SiC) ingot is used as the workpiece, the SiC ingot itself may have a flat end face on one axial side due to its manufacturing method (sublimation method), but an uneven end face on the other axial side. For this reason, when the workpiece is a SiC ingot, it is required that the uneven end face of the ingot can be securely gripped.

[0008] Specifically, the uneven end face of this type of ingot does not simply have a flat surface inclined relative to the axis of the workpiece, nor is it conical, but has an irregular three-dimensional shape. Therefore, the clamping part that grips the end face on that side must be able to follow the irregular three-dimensional shape while pressing the end face in the axial direction and holding (gripping) the workpiece. "Irregular three-dimensional shape" means that each ingot produced has a different shape.

[0009] In light of the above background, the present invention proposes a gripping device for a workpiece grinding device that can securely grip a workpiece having an end face with an irregular three-dimensional shape, and that has a structure that can stably grip the workpiece without applying excessive axial compressive force to the workpiece.

[0010] The gripping device in the workpiece grinding apparatus described in claim 1 comprises a pair of clamping sections that face each other in the longitudinal direction of the support table, grip a workpiece when they approach each other, and are supported by a support section so as to be rotatable around their axis together with the workpiece while gripping the workpiece; a rotational drive device that rotates each of the pair of clamping sections gripping the workpiece together with the support section around its axis; and a linear drive device that linearly moves at least one of the pair of clamping sections, together with the support section that supports it, in the longitudinal direction relative to the support table, wherein either one of the pair of clamping sections or the other clamping section has a plurality of gripping members that are independent of each other as a follower clamping section, and the plurality of gripping members are stored within the follower clamping section so as to be able to freely protrude and retract from an end face of the follower clamping section, and when the workpiece is gripped in the axial direction between the other clamping section or the end face of one of the clamping sections, the axial tip faces of all of the gripping members grip the workpiece together with the end face of the other clamping section or one of the clamping sections.

[0011] "A pair of clamps that face each other in the longitudinal direction of the support table and grip the workpiece when they approach each other... supported by the support" means that, as shown in Figures 1 to 3, a pair of clamps 4, 5 that grip (sandwich) the workpiece 12 in its axial direction are arranged facing each other in the longitudinal direction of the support table 2 that supports the workpiece grinding device 1, and each clamp 4, 5 is supported (held) by support sections 6, 7, respectively. "The longitudinal direction of the support table 2" refers to the length direction (long side direction) of the support table 2 when viewed in a plan or elevation. "The axial direction of the workpiece 12" refers to the axial direction of the workpiece 12.

[0012] The phrase "a pair of clamping parts supported by a support part so as to be rotatable about an axis together with the workpiece while gripping the workpiece" means that when the pair of clamping parts 4, 5 are gripping the workpiece 12, the pair of clamping parts 4, 5 and the workpiece 12 can rotate about an axis together with the support parts 6, 7. The "axis" refers to the axis of the clamping parts 4, 5 and the support parts 6, 7, but is also the axis of the workpiece 12. The pair of clamping parts 4, 5 constitute the gripping device 3.

[0013] The "rotation drive device that rotates each of a pair of clamping parts that grip a workpiece around the axis of the clamping parts together with the support parts" refers to a rotation drive device that rotates each of a pair of clamping parts 4, 5 that grip a workpiece 12 and the support parts 6, 7 that support each of the clamping parts 4, 5 around the axis of the clamping parts 4, 5. The rotation drive device is a motor or the like. The rotation drive device links and rotates one clamping part 4 (5) and the other clamping part 5 (4) together with the support parts 6, 7 that support them, respectively.

[0014] The phrase "a linear drive device that moves at least one of a pair of clamps, together with the support part that supports that clamp, in a linear direction relative to the support base" refers to the following: That is, the linear drive device 8 that moves either one of the pair of clamps 4, 5, 4 (5) and the support part 6 (7) that supports it back and forth (linearly) in the longitudinal direction of the support base 2 may be connected to only one of the clamps 4 (5) (support part 6 (7)), or may be connected to both clamps 4, 5 (support parts 6, 7). The linear drive device 8 is connected directly or indirectly to the clamps 4 (5) or support part 6 (7).

[0015] Basically, it is sufficient to reciprocate either one of the clamping parts 4 (5) (supporting part 6 (7)) so that the pair of clamping parts 4, 5 can grip the workpiece 12. If the clamping parts 4, 5 (supporting parts 6, 7) on both sides are allowed to reciprocate, the efficiency of gripping the workpiece 12 can be improved or fine adjustments can be made.

[0016] "One or the other of the pair of clamps functions as a follower clamp" means that one of the pair of clamps 4, 5, 4 (5) or the other clamp 5 (4) functions (behaves) as a follower clamp. "Having multiple independent clamping materials as follower clamps" means that multiple or multiple clamping materials 41 are stored independently of each other in one of the clamps 4 (5) that serves as a follower clamp.

[0017] "The multiple gripping materials are stored in the following clamping portion so as to be able to freely protrude and retract from the end face of the following clamping portion" means that each of the multiple (plural) gripping materials 41 is stored in the following clamping portion 4 (5) so as to be able to protrude and retract independently of the other gripping materials 41. The gripping materials 41 are stored in the following clamping portion 4 (5) so as to be able to protrude and retract from its end face in the axial direction of the following clamping portion 4 (5). "The axial direction of the following clamping portion 4 (5)" refers to the direction of linear motion of the following clamping portion 4 (5), and is also the axial direction of the following clamping portion 4 (5).

[0018] Whether the following clamp portion is one of the clamp portions 4 (5) or the other clamp portion 5 (4), the gripping material 41 can freely appear and disappear from the end face of the following clamp portion 4 (5) on the workpiece 12 side.

[0019] The follower clamping unit 4 (5) grips the irregular three-dimensional end face of the workpiece 12 with a plurality of gripping members 41 together with one or the other of the clamping units 5 (4). As shown in Figure 7, the plurality of gripping members 41 are basically arranged evenly distributed around the circumference at equal radial distances from the center of the end face of the follower clamping unit 4 (5). The "radial direction" refers to the radial direction when the end face of the clamping unit 4 (5) is circular.

[0020] When multiple gripping materials 41 are arranged evenly distributed circumferentially at positions spaced equal radial distances from the center of the end face of the following clamping portion 4 (5), when the multiple gripping materials 41 grip the workpiece 12, they can apply an even compressive force in the axial direction even though they are distributed at multiple locations on the end face of the workpiece 12, so the workpiece 12 can be gripped while being stabilized.

[0021] The multiple gripping members 41, together with the clamping member 5(4) paired with the following clamping member 4(5), share the compressive force required to grip the workpiece 12. In other words, the multiple gripping members 41 distribute and bear the reaction force of the compressive force applied to the workpiece 12 when gripping the workpiece 12, so that the reaction force acting on the following clamping member 4(5) is distributed in the circumferential direction.

[0022] When the gripping members 41 are rod-shaped as shown in Figure 6, at least three gripping members are sufficient to stably grip the workpiece 12. For example, when the gripping members 41 are plate-shaped or curved, with a width in the circumferential direction of the clamping portion 4 (5), two gripping members (two sheets) positioned on either side of the center of the end face of the clamping portion 4 (5) may be sufficient. "Curved plate-shaped" refers to a convex curve or bend on the radially outer side of the center of the end face of the clamping portion 4 (5). However, the ability of the follower clamping portion 4 (5) to follow the end face of the workpiece 12, which has an irregular three-dimensional shape, is higher when the gripping members 41 are rod-shaped and there are more of them.

[0023] Because each gripping material 41 can independently protrude and retract from the following clamping portion 4 (5), it is possible for each gripping material 41 to press the end face of the workpiece 12 in the axial direction at its respective storage position when protruding, in accordance with the shape of the end face of the workpiece 12, which has an end face with an irregular three-dimensional shape, and thereby grip the workpiece 12.

[0024] In particular, when the end of the gripping member 41 on the workpiece 12 side has a shape in which the cross-sectional area perpendicular to the axis of the gripping member 41 decreases from the support portion 6 (7) side to the workpiece 12 side as shown in Figure 6 (claim 2), each gripping member 41 receives hydraulic pressure, such as oil pressure, required to hold the workpiece 12 from its back side (support portion 6 side), and can follow the subtle irregular shape of the end face of the workpiece 12. "Support portion 6 (7)" refers to the support portion that supports the following clamp portion 4 (5) that houses the gripping member 41.

[0025] For example, if the gripping material 41 is a rod with a uniform cross-sectional shape along its entire length, each gripping material 41 must have a cross-sectional area (thickness) sufficient to receive the hydraulic pressure required to hold the workpiece 12 from its axial back surface. If the tip surface on the workpiece 12 side also has an area equal to that cross-sectional area, the workpiece 12 will come into contact with a surface with a constant area, making it difficult to follow irregular shapes such as subtle irregularities on the end surface of the workpiece 12. In this case, the gripping material 41 will try to move to a part where it can more stably hold the workpiece 12, which may cause the workpiece 12 to shift from the optimal gripping position. The "axial direction of the gripping material 41" refers to the axial direction of the gripping material 41, which is also the axial direction of the follower clamp unit 4 (5).

[0026] On the other hand, since the area of ​​the tip end face of the gripping member 41 on the workpiece 12 side is smaller than the area on the side receiving the hydraulic pressure, the contact state with the workpiece 12 becomes closer to point contact than surface contact, in comparison with the case where the cross-sectional shape is uniform over the entire length, and it becomes easier to accommodate and follow the fine irregularities on the end face of the workpiece 12. As a result, it becomes easier to stably hold the workpiece 12 without it shifting relative to the pair of clamping parts 4, 5.

[0027] The ability of each gripping member 41 to independently protrude and retract from the follower clamp unit 4 (5) is made possible by, for example, supplying pressure fluid such as pressure oil from the axial rear side of the gripping member 41 into the multiple storage sections 42 that store each gripping member 41 in the follower clamp unit 4 (5), as shown in Figure 6, and applying equal fluid pressure to the axial back surface of each gripping member 41. The "axial back surface of the gripping member" refers to the surface of the gripping member 41 opposite to the tip surface on the workpiece 12 side. The cross-sectional areas perpendicular to the axes of all storage sections 42 are equal, and the cross-sectional areas perpendicular to the axes of all gripping members 41 are equal.

[0028] In this case, equal hydraulic pressure acts on the axial back surface of each gripping member 41, so that each gripping member 41 can press the workpiece 12 toward one or the other clamp section 5 (4) with equal pressure, regardless of the shape of the end face of the workpiece 12. When all gripping members 41 press the workpiece 12, there is no difference in the pressure with which each of the multiple gripping members 41 holds the workpiece 12, so uneven pressure does not act on the end face of the workpiece 12, and no eccentric load is applied to the workpiece 12.

[0029] As described above, each gripping member 41 in the following clamping unit 4 (5) presses the end face of the workpiece 12 in the axial direction at its respective storage position according to the shape of the end face of the workpiece 12 having an irregular three-dimensional end face. As a result, all gripping members 41, together with the other clamping unit 5 (4) or one clamping unit 4 (5), press the end face of the workpiece 12 having an irregular three-dimensional end face in the axial direction, making it possible to securely grip the workpiece 12.

[0030] In addition, since each gripping material 41 presses the workpiece 12 toward the other or one of the clamping portions 5 (4) with equal pressure, it is possible to grip the workpiece 12 stably without applying excessive axial compressive force to the workpiece 12.

[0031] When the linear drive device 8 moves the follower clamping unit 4 toward the workpiece 12, a detector 43 may be installed (fixed) on the end face of the follower clamping unit 4 on the workpiece 12 side as shown in Figure 6, in order to issue a command to the motor 81 of the linear drive device 8 to stop the follower clamping unit 4 upon contact with the workpiece 12. In this case, when the follower clamping unit 4 moves toward the workpiece 12, it is desirable that the detector 43, rather than any of the gripping members 41, always come into contact with the end face of the workpiece 12 first, regardless of the shape of the end face of the workpiece 12 on the follower clamping unit 4 side.

[0032] From this point of view, it is appropriate that when all the gripping members 41 are immersed in the follower clamping unit 4 as shown in Fig. 6, the tip end faces of the detection members 43 on the workpiece 12 side are positioned closer to the workpiece 12 than the tip end faces of all the gripping members 41 on the workpiece 12 side (claim 3). In other words, in order to detect that the detection members 43 have come into contact with the workpiece 12, it is appropriate that none of the gripping members 41 come into contact with the workpiece 12 before the detection members 43 come into contact.

[0033] This is because if any of the gripping materials 41 contacts the workpiece 12 before the detection material 43, an error may occur in the optimal detection timing by the detection material 43. However, if the hydraulic pressure applied to the back surface of each gripping material 41 is released and the gripping material 41 is free to move axially within the storage section 42, the effect of contact of the gripping material 41 on the detection material 43 is small. In Figure 6, the lower gripping material 41 shows the immersed state. The two-dot chain line showing the upper gripping material 41 moving toward the storage section 42 shows the immersed state.

[0034] The contact of the detection material 43 with the workpiece 12 is detected by a sensor 94 installed behind the support part 6 that supports the following clamp part 4, and the signal (information) is transmitted to the motor 81 of the linear drive device 8, causing the linear drive device 8 to stop moving the following clamp part 4 (support part 6) toward the workpiece 12.

[0035] When all of the gripping materials 41 are immersed in the following clamping portions 4, the tip surface of the detection material 43 on the workpiece 12 side is positioned closer to the workpiece 12 than the tip surfaces of all of the gripping materials 41. This makes it possible to achieve a state in which the detection material 43 comes into contact with the end surface of the workpiece 12 before any of the gripping materials 41 (all of the gripping materials 41) regardless of the end surface shape of the workpiece 12, especially when a SiC ingot whose end surface shape on the following clamping portion 4 side is an overall convex or uneven three-dimensional shape is used as the workpiece 12.

[0036] In particular, when the workpiece 12 is a SiC ingot, the irregular three-dimensional shape is often located at or near the center of the end face of the workpiece 12, or the periphery is convex, so it is reasonable to place the detection material 43 in the center of the end face of the following clamping unit 4 on the workpiece 12 side, as shown in Figures 6 and 7.

[0037] Furthermore, when the workpiece 12 is gripped by all the gripping members 41 of the following clamping unit 4, it is necessary that the detection members 43 are not involved in gripping the workpiece 12, that is, that the detection members 43 do not hinder the gripping of the workpiece 12 by all the gripping members 41. For this purpose, when all the gripping members 41 are protruding, it is appropriate that the tip surface of the gripping member 41 on the workpiece 12 side is positioned closer to the workpiece 12 than the tip surface of the detection member 43 on the workpiece 12 side (claim 4).

[0038] When all the gripping materials 41 are protruded, the tip surfaces of all the gripping materials 41 on the workpiece 12 side are positioned closer to the workpiece 12 than the tip surfaces of the detection materials 43, so that when the following clamping unit 4 moves toward the workpiece 12, some part of the tip surfaces of all the gripping materials 41 always comes into contact with the end surface of the workpiece 12, making it possible to grip the workpiece 12 together with the fixed clamping unit 5.

[0039] The phrase "when the multiple gripping members grip the workpiece in the axial direction between the end face of the other clamping portion or one of the clamping portions, the axial tip faces of all of the gripping members grip the workpiece together with the end face of the other clamping portion or one of the clamping portions" in claim 1 means the following: That is, when all of the gripping members 41 in the follower clamping portion 4 grip the workpiece 12 in the axial direction between the end face of the other clamping portion or one of the clamping portions 5 (4), all of the gripping members 41 and the end face of the other clamping portion or one of the clamping portions 5 (4) pinch and grip the workpiece 12 in the axial direction. The "axial tip faces of the gripping members" refers to the end faces of the gripping members 41 on the side of the other clamping portion 5 (4) of the pair.

[0040] The shape of the end face of the clamping part 5 that pairs with the follower clamping part 4 on the workpiece 12 side is not particularly limited, and depending on the type (material) of the workpiece 12, it may have a flat surface inclined with respect to the axis of the workpiece 12 or a non-flat shape. However, when the workpiece 12 is the SiC ingot described above, one end face of the workpiece 12 has an irregular three-dimensional shape, while the other end face is a flat surface perpendicular to the axis. Therefore, for a SiC ingot workpiece 12, it is appropriate that the end face of the clamping part 5 that pairs with the follower clamping part 4 on the workpiece 12 side has a flat surface perpendicular to the axis of the workpiece 12 (claim 5).

[0041] In this case, the end face of the clamping part 5 that is paired with the following clamping part 4 on the workpiece 12 side is a flat surface perpendicular to the axis of the workpiece 12, so that the clamping part 5 that is paired with the following clamping part 4 comes into surface contact with one end face of the SiC ingot workpiece 12, making it possible to stably grip the workpiece 12.

[0042] Furthermore, since the end face of the clamping portion 5 that is paired with the following clamping portion 4 on the workpiece 12 side is a flat surface, when the workpiece 12, one side of which is flat, is gripped between the clamping member 41 of the following clamping portion 4, the workpiece 12 can be gripped without tilting the axis of the workpiece 12 relative to the axis of both clamping portions 4 and 5, making it possible to accurately polish or grind the peripheral surface of the workpiece 12.

[0043] Of the pair of clamping sections that grip the workpiece, one clamping section serves as a follower clamping section, and multiple gripping materials are stored within the follower clamping section so that they can freely appear and disappear from the end face of the other clamping section.Therefore, when the workpiece is gripped together with the other clamping section, the axial tip surfaces of all gripping materials, together with the end face of the other clamping section, can securely grip a workpiece having an end face with an irregular three-dimensional shape.

[0044] Furthermore, since the multiple gripping members can be freely inserted and removed independently from the end faces of the following clamping sections, each gripping member can press the end face of the workpiece in the axial direction at its respective storage position according to the shape of the end face of the workpiece, which has an irregular three-dimensional shape, and can grip the workpiece stably together with the other clamping section.

[0045] In addition, since each gripping member presses the workpiece toward the other or one of the clamping portions with equal pressure, the workpiece can be gripped without applying excessive axial compressive force to the workpiece.

[0046] 1 is a plan view showing the entire workpiece grinding device. It is an elevation view of FIG. 1. (a) is a plan view showing a pair of clamping units in FIG. 1 gripping a workpiece, and (b) is a cross-sectional view taken along line x-x in (a). It is an enlarged view of the pair of clamping units and the workpiece in FIG. 3-(a). It is a longitudinal cross-sectional view showing an example of the supply of pressure fluid for controlling the extension and retraction of the follower clamping unit and the support unit that supports it, as well as the multiple gripping members. It is an enlarged view of the follower clamping unit portion in FIG. 5. It is a view taken along line y-y in FIG. 6. It is a partial cross-sectional elevation view showing the follower clamping unit and the fixed clamping unit gripping the workpiece in the axial direction. It is a plan view showing the workpiece, the follower clamping unit, and the fixed clamping unit enclosed in a liquid-proof box attached to the grinding unit. (a) is a cross-sectional view taken along line a-a in FIG. 9, (b) is a cross-sectional view taken along line b-b in (a), and (c) is a cross-sectional view taken along line c-c in (a).

[0047] 1 and 2 show an example of the configuration of a workpiece grinding device 1 having a pair of clamping units 4, 5 that face each other in the longitudinal direction of a support table 2, grip (clamp) a workpiece 12 when they approach each other, and are supported by support units (spindles) 6, 7 so as to be rotatable about their axes together with the workpiece 12 while gripping the workpiece 12. The pair of clamping units 4, 5 constitute a gripping device 3. The support table 2 is a stand assembled in the shape of a three-dimensional frame for supporting the workpiece grinding device 1.

[0048] In addition to the gripping device 3, the workpiece grinding apparatus 1 is equipped with a rotational drive device that rotates each of the pair of clamping sections 4, 5 gripping the workpiece 12 together with the support sections 6, 7 that support them about the respective axes of both clamping sections 4, 5, and a linear drive device 8 that moves at least one of the clamping sections 4 (5) together with the support section 6 (7) that supports it in a linear manner in the longitudinal direction relative to the support table 2. The rotational drive devices are specifically workpiece rotation motors 98, 104 attached to the movable-side presser unit 9 and the fixed-side presser unit 10, respectively, which will be described later.

[0049] Of the pair of clamping parts 4, 5, either one of the clamping parts 4 or the other clamping part 5 is a follower clamping part, as shown in Figures 4 and 6, which can freely protrude and retract from the end face of the other clamping part 5 or one of the clamping parts 4 toward the workpiece 12 and has multiple gripping members 41 that are independent of each other.

[0050] The drawings show an example in which one clamp 4, which is part of the movable-side presser unit 9, behaves as a follower clamp having a gripping material 41, but there is also a case in which the other clamp 5, which is part of the fixed-side presser unit 10, acts as a follower clamp having a gripping material 41. Below, an example in which one clamp 4 is a follower clamp and the other clamp 5 is part of the fixed-side presser unit 10 will be described.

[0051] 1 and 2, the pair of clamping units 4, 5 are arranged so that their axis centers are positioned on the same straight axis on the support base 2, and a linear driving device 8 is indirectly connected to at least one of the clamping units 4 (5). In the example shown, the linear driving device 8 is connected to a movable-side presser unit 9 integrated with one of the clamping units 4, which is the follower clamping unit, but the linear driving device 8 may also be connected to the other clamping unit 5.

[0052] In the illustrated example, one of the clamping sections (following clamping section) 4 is integrated with the movable-side presser unit 9 at the support section 6 that supports it, and the linear driving device 8 is connected to the movable-side presser unit 9, so that the following clamping section 4 moves linearly in the longitudinal direction of the support table 2 relative to the fixed-side presser unit 10 when the linear driving device 8 is driven.

[0053] In the illustrated example, the other clamp portion 5 is integrated with the fixed-side presser unit 10 at the support portion 7 that supports it, as will be described later. In this relationship, the other clamp portion 5 does not move linearly in the longitudinal direction of the support base 2, and therefore, hereinafter, the clamp portion that pairs with the following clamp portion 4 will be referred to as the fixed clamp portion 5. Since the workpiece 12 basically has a cylindrical outer peripheral surface and a circular cross-sectional shape, the end faces of both the following clamp portion 4 and the fixed clamp portion 5 are basically circular.

[0054] The drawing shows an example in which the linear drive device 8 arranged on the support base 2 is configured from, for example, a motor 81 installed on the support base 2, a drive shaft 82 for converting the rotational force of the motor 81 into linear motion and transmitting the motion to the movable-side presser unit 9, a ball screw 85, etc. However, the linear drive device 8 may have any mechanism (configuration) and installation position as long as it is a mechanism that transmits power as linear motion to the movable-side presser unit 9 (one of the clamping sections (following clamping section) 4), and devices other than mechanisms using ball screws, etc. may also be used.

[0055] The drawings also show that the fixed-side presser unit 10, which is installed on the support table 2 adjacent to the grinding unit 11 in the width direction of the support table 2 and equipped with a grinding wheel 112 or the like shown in FIG. 10, which grinds or polishes the workpiece 12 as shown in FIGS. 1, 3, and 9, is fixed to the support table 2 so that the fixed-side presser unit 10 does not move linearly.

[0056] The grinding unit 11 is installed on the support table 2 so as to be able to move linearly in the longitudinal direction of the support table 2, and moves linearly when a motor 114 attached to the grinding unit 11 rotates, as shown in Figure 1. The grinding unit 11 is equipped with a liquid-proof box 111 that houses a grinding wheel 112 and other components, as well as a cooling nozzle 113 that sprays a coolant to cool the workpiece 12 during grinding, etc., and the grinding wheel 112 and other components are stored in the liquid-proof box 111 as described below.

[0057] Since the fixed side pressure unit 10 is fixed to the support table 2, when the workpiece 12 is gripped by the pair of clamping sections 4, 5, the movable side pressure unit 9, which is equipped with the following clamping section 4 and the support section 6 that supports it, moves linearly (approaches) toward the fixed side pressure unit 10 when the linear drive device 8 is driven, and the following clamping section 4 and the fixed clamping section 5 grip the workpiece 12.

[0058] 1 , as motor 81 constituting linear drive device 8 rotates, drive shaft 82 directly connected to motor 81 rotates. At the same time, driven gear 84 meshing with drive gear 83 connected to the movable-side presser unit 9 side of drive shaft 82 rotates. A ball screw 85 is connected to driven gear 84 in parallel with drive shaft 82, and ball screw 85 rotates as driven gear 84 rotates, and nut 86 threadedly engaged with the movable-side presser unit 9 side of ball screw 85 reciprocates (linearly moves) in the axial direction relative to ball screw 85.

[0059] The nut 86 is a part of a main body 91 that constitutes the movable-side presser unit 9, and the main body 91 reciprocates (linearly moves) in the axial direction of the ball screw 85 simultaneously with the reciprocating movement of the nut 86. A control unit 92 having a control device that controls the protrusion and retraction of the gripping material 41 housed so as to be freely protruded and retracted in the follower clamp unit 4 is integrated on one side of the main body 91 in a direction perpendicular to the reciprocating direction, and the control unit 92 reciprocates (linearly moves) together with the main body 91 in the axial direction of the ball screw 85. The main body 91 of the movable-side presser unit 9 runs on parallel guides 93, 93 that are laid on the support base 2 in parallel to the axial direction of the ball screw 85, and is guided by both guides 93, 93.

[0060] The support part 6 is integrally connected to the control part 92 of the movable-side presser unit 9, and the follower clamp part 4 is integrally connected to the end of this support part 6 on the fixed clamp part 5 side. The support part 6 is connected to the fixed clamp part 5 side of the control part 92. The support part 6 and follower clamp part 4 reciprocate together with the control part 92 when the motor 81 rotates, and when they move towards the fixed clamp part 5 side, they grip the workpiece 12 together with the fixed clamp part 5 which is supported in a fixed state by the support part 7 which is part of the fixed-side presser unit 10.

[0061] The fixed side pressure unit 10 equipped with the fixed clamp section 5 is fixed to the support table 2, so when gripping the workpiece 12, the movable side pressure unit 9 moves toward the fixed side pressure unit 10, and the following clamp section 4 and the fixed clamp section 5 grip the workpiece 12.

[0062] 4 shows an example in which a SiC ingot is used as the workpiece 12, with one end face having an irregular three-dimensional shape and the other end face forming a flat surface perpendicular to its axis. The irregular three-dimensional end face of the workpiece 12 faces the follower clamp unit 4, and the flat end face faces the fixed clamp unit 5. In this relationship, the end face of the fixed clamp unit 5 facing the follower clamp unit 4 forms a flat surface perpendicular to the axis of the workpiece 12. The workpiece 12 is inserted between the follower clamp unit 4 and the fixed clamp unit 5 by a loader unit, which will be described later.

[0063] As described above, the follower clamping section 4 has a plurality of gripping members 41 that can freely protrude and retract from the end face on the fixed clamping section 5 side. The plurality of gripping members 41 are stored in a storage section 42 formed in the follower clamping section 4 so that they can protrude and retract independently from the end face of the follower clamping section 4, as shown in Figures 4 and 6. When gripping the workpiece 12, the tip ends of the plurality of gripping members 41 on the workpiece 12 side protrude from the end face of the follower clamping section 4, and when the tip faces of the gripping members 41 grip the workpiece 12 in the axial direction between the end face of the fixed clamping section 5 and the end face of the fixed clamping section 5, the axial tip faces of all the gripping members 41 grip the workpiece 12 together with the end face of the fixed clamping section 5, as shown in Figure 4.

[0064] The workpiece 12 is inserted between the end faces of the clamping parts 4 and 5, with a distance maintained between the opposing end faces, while being held by a loader unit (not shown) that carries the workpiece 12 in and out between the pair of clamping parts 4 and 5. However, in order to avoid any influence on the peripheral surface, which is the grinding surface, due to the workpiece 12 being held directly by the loader unit, a supported material 12A is bonded with an adhesive or the like to the end face of the workpiece 12 on the fixed clamping part 5 side, as shown in Figure 4, in order to be held directly by the loader unit.

[0065] In this case, the workpiece 12 is held by the loader unit at the peripheral surface of the supported material 12A integrated with it and is moved toward the fixed clamp unit 5 until the end face of the supported material 12A on the fixed clamp unit 5 side comes into surface contact with the end face of the fixed clamp unit 5. By making surface contact with the end face of the supported material 12A, a uniform compressive force is applied in the axial direction of the workpiece 12 in a state of contact with the workpiece 12 due to the movement of the follower clamp unit 4 toward the fixed clamp unit 5, and the workpiece 12 is gripped with a constant compressive force.

[0066] When the end face of the supported material 12A on the side of the fixed clamp unit 5 comes into contact with the end face of the fixed clamp unit 5, the end face of the workpiece 12 side of the air supply pipe 102 for blowing cleaning air shown in FIG. 8, which is disposed in the control unit 101 of the fixed-side presser unit 10 to which the support unit 7 supporting the fixed clamp unit 5 is connected, reacts as a sensor dog. At the same time, a sensor 103 installed behind the control unit 101 (opposite the fixed clamp unit 5) detects the contact of the workpiece 12 (supported material 12A) with the end face of the fixed clamp unit 5, thereby stopping the loader unit from moving the workpiece 12 toward the fixed clamp unit 5. The end face of the air supply pipe 102 on the side of the workpiece 12 comes into contact with a protrusion 12A1 formed or protruding from the end face of the supported material 12A on the side of the fixed clamp unit 5.

[0067] The loader unit is arranged on the side of the fixed-side presser unit 10 opposite the grinding unit 11 so that it can move back and forth (linearly) in the axial direction of the fixed clamp unit 5. The loader unit may be supported by the support table 2. While holding the workpiece 12, the loader unit moves the workpiece 12 between the trailing clamp unit 4 and the fixed clamp unit 5 by linear motion in the longitudinal and width directions of the support table 2, and stops once the flat end face of the workpiece 12 coincides with the end face position of the fixed clamp unit 5. At this time, the axis of the workpiece 12 and the axes of the trailing clamp unit 4 and the fixed clamp unit 5 are parallel to each other.

[0068] After the loader unit places the workpiece 12 between the follower clamp unit 4 and the fixed clamp unit 5, it moves the workpiece 12 slightly to make fine adjustments toward the fixed clamp unit 5, and when the workpiece 12 comes into surface contact with the end face of the fixed clamp unit 5, it receives a command from the sensor 103 and stops the workpiece 12. If there is any problem with the follower clamp unit 4 and the fixed clamp unit 5 gripping the workpiece 12, the loader unit moves away from the stopping position of the workpiece 12.

[0069] After the workpiece 12 has stopped, the movable-side presser unit 9 moves toward the workpiece 12 (toward the fixed-side presser unit 10) by operating the linear drive device 8. When the detection material 43 fixed to the end surface of the follower clamp unit 4 on the workpiece 12 side shown in Figures 6 and 7 comes into contact with any part of the irregular three-dimensional end surface of the workpiece 12, the sensor 94 shown in Figures 2 and 5 installed behind the movable-side presser unit 9 (on the opposite side from the follower clamp unit 4) detects the contact of the detection material 43 with the workpiece 12 and stops the movable-side presser unit 9 (linear drive device 8).

[0070] Here, the fixing position of the detection material 43 to the end face of the following clamping portion 4 is adjusted so that the tip surface of the detection material 43 on the end face of the following clamping portion 4, rather than any of the gripping materials 41 protruding from the end face of the following clamping portion 4 on the workpiece 12 side, can reliably come into contact with the end face of the workpiece 12 when the following clamping portion 4 moves toward the workpiece 12.

[0071] 6, when all the gripping members 41 are immersed in the storage section 42 of the follower clamping unit 4, the tip end surface of the detection member 43 on the workpiece 12 side is adjusted to be positioned closer to the workpiece 12 than the tip end surface of all the gripping members 41 on the workpiece 12 side when viewed in a direction perpendicular to the axial direction of the follower clamping unit 4. The detection member 43 is fixed to the end surface of the follower clamping unit 4 at this adjusted position.

[0072] In Figure 6, the tip surface of the uppermost gripping member 41 is shown to be aligned with the tip surface of the detection member 43, but in the immersed state, the gripping member 41 is stored in the storage section 42 as shown by the two-dot chain line. Note that although the detection member 43 is placed at the center of the end face of the follower clamping section 4 in Figures 6 and 7, it is not necessarily required to place the detection member 43 at the center of the end face.

[0073] The end face of the workpiece 12 on the side of the follower clamping unit 4 may have an irregular three-dimensional shape as shown in Fig. 4. A plurality of independent gripping members 41 are stored in the storage section 42 of the follower clamping unit 4 so that they can freely protrude and retract in the axial direction of the follower clamping unit 4, so that each gripping member 41 can follow this irregular three-dimensional shape and all gripping members 41 can come into contact with and press against the end face of the workpiece 12.

[0074] When gripping the workpiece 12, each gripping member 41 protrudes from the end face of the follower clamping member 4 on the workpiece 12 side (fixed clamping member 5 side) toward the workpiece 12, and when the end face on the workpiece 12 side of each gripping member 4 comes into contact with the end face of the workpiece 12, it receives a reaction force from the workpiece 12 and stops protruding from the follower clamping member 4. In this stopped state, each gripping member 41 receives a hydraulic pressure, which will be described later, and a constant compressive force acts on the workpiece 12 from each gripping member 41. The sum of the compressive forces acting on the workpiece 12 from all gripping members 41 is the reaction force acting on the workpiece 12 from the paired fixed clamping member 5, and this reaction force becomes the compressive force when the fixed clamping member 5 grips the workpiece 12.

[0075] In particular, in preparation for cases where the end face of the workpiece 12 on the follower clamping unit 4 side has a subtle uneven shape, it is desirable that the end of the gripping material 41 on the workpiece 12 side has a shape that tapers from the support unit 6 side toward the workpiece 12 side, as shown in Figures 4 and 6. More specifically, the end of the gripping material 41 on the workpiece 12 side has a shape in which the cross-sectional area perpendicular to the axis of the gripping material 41 decreases or gradually decreases from the support unit 6 side that supports the follower clamping unit 4 toward the workpiece 12 side.

[0076] Because the tip of the gripping material 41 has a tapered shape, even when the end surface of the workpiece 12 has a finely uneven shape as shown in Figure 4, each gripping material 41 can contact the end surface of the workpiece 12 essentially at a point or at a surface close to a point, making it possible to grip the workpiece 12 accurately and stably without moving (shifting) the workpiece 12 even slightly in a direction perpendicular to the axis.

[0077] Furthermore, when the workpiece 12 is gripped by the entire gripping material 41 of the following clamping section 4, in order to prevent the detection material 43 from being involved in gripping the workpiece 12, in other words, to prevent the detection material 43 from interfering with the gripping by the gripping material 41, the protruding length of the detection material 43 is adjusted so that when the entire gripping material 41 protrudes, the tip surface of the entire gripping material 41 on the workpiece 12 side is positioned closer to the workpiece 12 than the detection material 43.

[0078] When projected, the tip surface of the gripping member 41 on the workpiece 12 side is positioned closer to the workpiece 12 than the tip surface of the detecting member 43 on the workpiece 12 side, thereby preventing any part of the tip surface of the detecting member 43 from contacting the end surface of the workpiece 12 before any part of the tip surface of the gripping member 41. This is possible unless the center of the end surface of the workpiece 12 on the trailing clamping member 4 side has a three-dimensional shape that is extremely convex toward the trailing clamping member 4. When the gripping member 41 grips the workpiece 12, the detecting member 43 does not contact the workpiece 12 before the gripping member 41, thereby preventing malfunction due to the detecting member 43 contacting the workpiece 12.

[0079] 5, 6 and 8, a pressure fluid supply pipe 95 is arranged within the control section 92 of the movable-side presser unit 9 to supply pressure fluid for controlling the rise and fall of each gripping material 41, and pressure fluid such as pressure oil is supplied into the pressure fluid supply pipe 95 from a tank 99 by a hydraulic pump 96 through a control valve 97 such as an electromagnetic valve, as shown in Fig. 5. The pressure fluid supply pipe 95 branches out to each storage section 42 that stores each gripping material 41 within the follower clamp section 4, as shown in Fig. 6, and equal pressure fluid is supplied to the multiple storage sections 42 that store each gripping material 41, and equal hydraulic pressure such as oil pressure is applied to the axial back surface of each gripping material 41.

[0080] 6, the two-dot chain line representing the gripping member 41 indicates the protruding position and the retracted position of the gripping member 41, and the difference between these positions indicates the possible stroke of the gripping member 41. Basically, all of the gripping members 41 are not subjected to hydraulic pressure from the hydraulic fluid, and are therefore free to move in the axial direction, and are kept retracted into the storage section 42 of the follower clamp unit 4, with their tip surfaces not protruding beyond the detection member 43. This retracted state can also be maintained by utilizing the restoring force of, for example, placing some kind of spring, such as a coil spring, around each gripping member 41.

[0081] When the detection material 43 comes into contact with the end face of the workpiece 12 and the sensor 94 detects this, pressurized liquid is supplied from the tank 99 to each storage section 42 through the pressurized liquid supply pipe 95, and each gripping material 41 protrudes according to the shape of the end face of the workpiece 12 and stops when it comes into contact with the end face of the workpiece 12. When each gripping material 41 is stopped, it receives the pressure necessary for holding from the pressurized liquid in the storage section 42, and continues to grip the workpiece 12 together with the fixed clamping unit 5 with a constant compressive force. Because the compressive forces acting on the workpiece 12 from the follower clamping unit 4 and the fixed clamping unit 5 when gripping the workpiece 12 are balanced, the sum of the compressive forces from all gripping materials 41 is equal to the compressive force from the fixed clamping unit 5.

[0082] In addition, when all the gripping members 41 grip the workpiece 12, a uniform compressive force can be applied to the end face of the workpiece 12 from multiple locations in the axial direction. It is reasonable to arrange the multiple gripping members 41 at equal radial distances from the center of the end face of the follower clamping unit 4, and to distribute them evenly in the circumferential direction, as shown in Figure 7. While the drawing shows four rod-shaped (pin-shaped) gripping members 41, the number is arbitrary; if the gripping members 41 are rod-shaped, at least three will suffice. If the gripping members 41 are curved or bent plate-shaped, at least two will suffice.

[0083] When the multiple gripping members 41 grip the end face of the workpiece 12, the pressure of the pressurized fluid is adjusted so that an appropriate amount of fluid pressure necessary for gripping acts on each gripping member 41. When the gripping of the workpiece 12 by the multiple gripping members 41 is released after grinding of the peripheral surface of the workpiece 12 is completed, the hydraulic pump 96 is released and the pressurized fluid is returned to the tank 99 from the pressurized fluid supply pipe 95, the pressure acting on the back surface of each gripping member 41 is released, and the follower clamp unit 4 retreats from the workpiece 12.

[0084] Each gripping material 41 is free to move in the axial direction when the hydraulic pressure is released, but by placing a spring around the gripping material 41 as described above, the gripping material 41 can be automatically immersed (restored) into the storage section 42 when the hydraulic pressure is released. The restoring force (biasing force) of the spring is set to be smaller than the force of the hydraulic pressure acting on the back surface of each gripping material 41.

[0085] 1, 3 and 9 moves linearly in its longitudinal direction on the support table 2 by the rotation of a motor 114 connected thereto as a linear drive device when the workpiece 12 is held by the follower clamp unit 4 and the fixed clamp unit 5. Specifically, when the motor 114 rotates, the ball screw 115 moves linearly in response to the rotation of the motor 114, and simultaneously, the grinding unit 11, which is integrated with a nut threaded onto the ball screw 115, moves in the reciprocating direction of the movable-side presser unit 9.

[0086] As a result of the grinding unit 11 moving toward the movable-side presser unit 9, the fixed clamp unit 5, workpiece 12, and follower clamp unit 4 are taken into and enclosed by a liquid-proof box 111 attached to the grinding unit 11. With the fixed clamp unit 5, workpiece 12, and follower clamp unit 4 enclosed by the liquid-proof box 111, a grinding wheel 112 mounted in the liquid-proof box 111 shown in Fig. 10 comes into contact with the circumferential surface of the rotating workpiece 12 while rotating, thereby grinding the circumferential surface of the workpiece 12. At this time, the workpiece 12 is kept at a certain temperature or below by coolant sprayed from a coolant nozzle 113.

[0087] 10-(b), an opening 111b having a shape corresponding to the cross-sectional shape of the follower clamp 4 is formed in the wall plate 111a on the movable-side presser unit 9 side of the liquid-proof box 111. This opening 111b is for taking in at least a portion of the axial direction of the follower clamp 4 into the liquid-proof box 111 when the grinding unit 11 moves toward the movable-side presser unit 9. A liquid-proof brush 117 is installed around the opening 111b on the inner peripheral surface of the wall plate 111a to prevent the coolant from the coolant nozzle 113 from spraying out of the liquid-proof box 111 when the follower clamp 4 enters the liquid-proof box 111 through the opening 111b.

[0088] With the fixed clamp unit 5 to the follower clamp unit 4 housed within the liquid-proof box 111, the support units 6 and 7 are rotated about their respective axes by the drive of work rotation motors 98 and 104, which serve as rotation drive devices attached to the rear of the movable-side hold-down unit 9 and the fixed-side hold-down unit 10 shown in Figures 1 and 2, respectively, and the follower clamp unit 4 and the fixed clamp unit 5 are rotated together with the work 12. The drive shafts of the work rotation motors 98 and 104 are connected to each other within the movable-side hold-down unit 9 and the fixed-side hold-down unit 10, and by synchronizing the work rotation motors 98 and 104, they rotate simultaneously at a uniform speed.

[0089] The workpiece 12 rotates about its axis together with the supports 6 and 7, thereby grinding or polishing the peripheral surface of the workpiece 12 with the grinding wheel 112. When grinding the peripheral surface of the workpiece 12, the grinding wheel 112 is rotated in the opposite direction to the rotation of the workpiece 12. In Figures 9 and 10, reference numeral 116 denotes a notch grinding wheel for forming grooves in the axial direction of the workpiece 12 while the rotation of the workpiece 12 is stopped.

[0090] 1...Workpiece grinding device, 2...Support table, 3...Gripping device, 4...One clamping section (following clamping section), 41...Gripping material, 42...Storage section, 43...Detection material, 5...Other clamping section (fixed clamping section), 6...Support section (of one clamping section), 7...Support section (of the other clamping section), 8...Linear drive device, 81...Motor, 82...Drive shaft, 83...Drive gear, 84...Driven gear, 85...Ball screw, 86...Nut, 9...Movable side presser unit, 91...Main body, 92...Control section, 93...Guide, 94...Sensor, 95...Pressure fluid supply pipe, 96...Hydraulic pressure pump, 97...Control valve, 98...Workpiece rotation motor (rotation drive device), 99...Tank, 10...Fixed side presser unit, 101...Control section, 102...Air blowing pipe, 103...Sensor, 104...Workpiece rotation motor (rotation drive device), 11: Grinding unit, 111: Liquid-proof box, 111a: Wall plate, 111b: Opening, 112: Grinding wheel, 113: Cooling nozzle, 114: Motor, 115: Ball screw, 116: Notch grinding wheel, 117: Liquid-proof brush, 12: Workpiece, 12A: Supported material, 12A1: Protrusion.

Claims

1. A gripping device for a workpiece grinding machine comprising: a pair of clamping sections that face each other in the longitudinal direction of a support table, grip a workpiece when they approach each other, and are supported by a support section so that they can rotate around their axis together with the workpiece while gripping the workpiece; a rotary drive device that rotates each of the pair of clamping sections gripping the workpiece together with the support section around its axis; and a linear drive device that moves at least one of the pair of clamping sections, together with the support section that supports it, in a linear direction longitudinally relative to the support table, wherein either one of the pair of clamping sections or the other clamping section has a plurality of independent gripping members as a trailing clamping section, and the plurality of gripping members are stored within the trailing clamping section so as to be able to freely protrude and retract from the end face of the trailing clamping section, and when the workpiece is gripped in the axial direction between the other clamping section or the end face of one of the clamping sections, the axial tip faces of all of the gripping members grip the workpiece together with the end face of the other clamping section or one of the clamping sections.

2. A gripping device in a work grinding device as described in claim 1, characterized in that the end of the gripping material on the work side has a shape in which the cross-sectional area perpendicular to the axis of the gripping material decreases from the support side to the work side.

3. A gripping device for a work grinding machine as described in claim 1 or claim 2, characterized in that a detection material is installed on the end face of the workpiece side of the following clamping section, which contacts the end face of the workpiece when the following clamping section moves towards the workpiece side and transmits a signal of this contact to the linear drive device, and when all of the gripping materials are immersed in the following clamping section, the tip face of the detection material on the workpiece side is positioned closer to the workpiece than the tip faces of all of the gripping materials on the workpiece side.

4. A gripping device in a work grinding machine as described in claim 1 or claim 2, characterized in that when all of the gripping materials are protruded, the tip surfaces of all of the gripping materials on the work side are positioned closer to the work side than the tip surfaces of the detection materials on the work side.

5. A gripping device in a work grinding device as described in claim 1 or claim 2, characterized in that the other clamping portion that pairs with the following clamping portion, or the end face of one of the clamping portions on the following clamping portion side, has a flat surface that is perpendicular to the axis of the workpiece.

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