Double-ended surface grinding machine

Abstract

The present invention provides a double-ended surface grinding apparatus that can stably hold a workpiece within a carrier and suitably grind both sides of the workpiece. [Solution] The double-ended surface grinding device (1) comprises a carrier (70) having a circular housing hole (71) formed therein for rotatably housing a thin plate-shaped workpiece W, first and second workpiece holders (30, 40) that hold the workpiece housed in the housing hole from both sides with static pressure, and first and second grinding wheels (91, 95) positioned eccentrically with respect to the center of the housing hole on both sides of the workpiece held by the first and second workpiece holders. The first and second grinding wheels rotate in the same direction relative to each other and contact the surfaces to be ground on both sides of the workpiece, while the carrier is fixed in a non-rotatable state, thereby rotating the workpiece within the housing hole and grinding the surfaces to be ground.

Description

Technical Field

[0001] The present disclosure relates to a double-sided surface grinding device.

Background Art

[0002] A double-sided surface grinding device for grinding both surfaces of a thin plate-like workpiece such as a semiconductor wafer to finish it flat is known. The double-sided surface grinding device includes a carrier, a rotating device, a pair of workpiece holders, and a pair of grinding wheels. The carrier has an accommodation hole for accommodating the workpiece. A notch trigger that protrudes into the accommodation hole is provided on the carrier. The notch trigger fits into a notch formed on the outer peripheral surface of the workpiece.

[0003] The rotating device rotates the carrier. Since the workpiece is fitted and supported by the carrier by the notch trigger, the workpiece rotates integrally with the carrier. The pair of workpiece holders hold the workpiece fitted and supported by the carrier in a non-contact manner from both sides by the pressure of a fluid. The pair of grinding wheels grind both surfaces of the workpiece by being applied to both surfaces of the workpiece that is being forcibly rotated together with the carrier while rotating by the operation of a drive motor.

[0004] An example of such a double-sided surface grinding device is disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, there has been a trend towards thinner workpieces due to demands for improved product yield. In the double-ended surface grinding machine described above, if the carrier is thicker than the workpiece, the grinding wheel will interfere with the carrier during grinding. Therefore, the carrier needs to be thinner than the workpiece to avoid interference with the grinding wheel. Consequently, as workpieces become thinner, the carrier must also be made thinner.

[0007] However, if the carrier is too thin, it becomes difficult to manufacture. Moreover, the carrier's rigidity will be reduced, making it prone to bending during workpiece grinding, which can lead to the workpiece falling off the carrier or poor grinding. Furthermore, when the workpiece is forcibly rotated together with the carrier, stress concentrates on the notched portion of the workpiece due to the load applied from the notch trigger. This raises concerns that the thinned workpiece may break as a result.

[0008] The object of this disclosure is to provide a double-ended surface grinding apparatus that can stably hold a workpiece within a carrier and suitably grind both sides of the workpiece. [Means for solving the problem]

[0009] A first aspect of this disclosure relates to a double-ended surface grinding apparatus. The double-ended surface grinding apparatus comprises a carrier having a circular housing hole formed therein for rotatably housing a thin plate-shaped workpiece; a pair of workpiece holders located on both sides in the thickness direction of the workpiece housed in the housing hole and holding the workpiece non-contact by fluid pressure; and a pair of grinding wheels located on both sides of the workpiece held by the pair of workpiece holders and eccentric with respect to the center of the housing hole. The pair of grinding wheels rotate in the same direction relative to each other and contact the surfaces to be ground on both sides of the workpiece, while the carrier is fixed in a non-rotatable state, thereby rotating the workpiece within the housing hole and grinding the surfaces to be ground.

[0010] In this first embodiment, the workpiece is rotatably housed in a housing hole of the carrier. A pair of grinding wheels rotate in the same direction relative to each other and contact the grinding surfaces on both sides of the workpiece. The workpiece rotates along the inner circumference of the housing hole due to the moment generated by the grinding resistance received from the grinding wheels. At this time, the carrier is fixed so as not to rotate. In other words, since the workpiece is not forced to rotate together with the carrier, stress does not concentrate on the part of the workpiece that is fitted and supported by the carrier, and damage to the workpiece can be suppressed. Furthermore, since the carrier is fixed during grinding of the workpiece, the parts of the carrier other than those corresponding to the grinding wheels can be made thicker, or the carrier can be sandwiched from both sides by other components such as a workpiece holder, making the carrier less likely to bend during grinding of the workpiece. In this way, the workpiece can be held stably within the carrier.

[0011] A second aspect of this disclosure is a double-ended surface grinding apparatus according to the first aspect, wherein recesses opening to the housing holes are formed on both sides of the carrier. The grinding wheel enters the recess and contacts the surface to be ground.

[0012] In this second embodiment, recesses are formed on both sides of the carrier. Each recess opens to a housing hole. The grinding wheel enters the recess. If the thickness of the portion of the carrier corresponding to the recess is thinner than the thickness of the workpiece, the grinding wheel that enters the recess can contact the surface of the workpiece to be ground and grind that surface. The portion of the carrier other than the part into which the grinding wheel enters can be made thicker without considering interference with the grinding wheel. This increases the rigidity of the carrier, making it less likely to bend during grinding of the workpiece.

[0013] A third aspect of the present disclosure is a double-ended surface grinding apparatus according to the second aspect, wherein the grinding wheel comprises a wheel base and a grinding wheel provided in an annular shape on one side surface of the wheel base. The recess is an arc-shaped groove that extends to correspond to the trajectory through which the grinding wheel passes as the grinding wheel rotates, and both ends in the longitudinal direction are open to the housing hole.

[0014] In this third embodiment, the recess is an arc-shaped groove that extends to correspond to the trajectory of the grinding wheel as it rotates. Both ends of the recess in the longitudinal direction are open to the housing hole. In a carrier having such a recess, the portion enclosed by the recess, i.e., the portion of the recess located on the housing hole side, can be made thicker as long as it does not interfere with the grinding wheel. This is advantageous for increasing the rigidity of the carrier.

[0015] A fourth aspect of this disclosure is a double-ended surface grinding apparatus according to the first aspect, wherein the carrier has a relief hole formed in which the housing hole is expanded outward and the housing hole is opened. The grinding wheel enters the relief hole and comes into contact with the surface to be ground.

[0016] In this fourth embodiment, a relief hole is formed in the carrier. The relief hole expands the receiving hole toward the outer circumference and opens to the receiving hole. The grinding wheel enters the relief hole. Once the grinding wheel enters the relief hole, it can grind the workpiece to a predetermined finished thickness even if the workpiece thickness is thinner than the carrier thickness. Therefore, even extremely thin workpieces of 100 μm or less can be ground. In addition, the carrier can be made thicker without considering interference with the grinding wheel. This increases the rigidity of the carrier, making it less likely to bend during workpiece grinding.

[0017] A fifth aspect of this disclosure is a double-ended surface grinding apparatus according to any one of the first to fourth aspects, wherein, in a front view of the housing hole, if a straight line passing through the center of the carrier and the rotation axis of the grinding wheel positioned at the grinding position of the surface to be ground is defined as a reference line, the center of the housing hole is located on one side of the reference line in a direction perpendicular to the reference line. The rotation direction of the grinding wheel is from one side to the other where the center of the housing hole is located in a direction perpendicular to the reference line at a point on the surface to be ground that passes through the reference line.

[0018] In this fifth aspect, the center of the accommodation hole is located on one side with respect to the reference line. The reference line is a straight line passing through the center of the carrier and the rotation axis of the grinding wheel disposed at the grinding position of the grinding surface in the front view of the accommodation hole. That is, the workpieces accommodated in the accommodation hole are unevenly distributed on the outer peripheral side of the carrier. And the grinding wheel rotates in a direction from one side where the center of the accommodation hole is located to the other side in a direction orthogonal to the reference line at a location passing through the reference line on the grinding surface. According to this, it is possible to suppress the workpieces from being damaged by the grinding operation as compared with the case where the rotation direction of the grinding wheel is the opposite direction.

[0019] A sixth aspect of the present disclosure is a double-sided surface grinding apparatus according to any one of the first to fifth aspects, wherein the pair of workpiece holders sandwich and fix the carrier.

[0020] In this sixth aspect, the carrier is sandwiched and fixed by a pair of workpiece holders. Thereby, it is difficult for the carrier to bend during the grinding of the workpiece, and the workpiece can be stably held in the carrier. Also, the positioning of the pair of workpiece holders when supporting the workpiece in a non-contact manner can be performed by sandwiching the carrier. Therefore, it is not necessary to provide a positioning mechanism such as a stopper for positioning the workpiece holder, and the configuration of the double-sided surface grinding apparatus can be simplified.

Effects of the Invention

[0021] According to the double-sided surface grinding apparatus of the present disclosure, the workpiece can be stably held in the carrier, and both surfaces of the workpiece can be suitably ground.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a plan view showing the configuration of a double-sided surface grinding apparatus according to an embodiment. [Figure 2] FIG. 2 is a front cross-sectional view when the workpiece holder is in the position for attaching and detaching the workpiece. [Figure 3] FIG. 3 is a front cross-sectional view showing the configuration of the double-sided surface grinding apparatus. [Figure 4]Figure 4 is a side cross-sectional view when the double-sided surface grinding device is viewed from the right direction. [Figure 5] Figure 5 is a longitudinal cross-sectional view showing the structure of the carrier. [Figure 6] Figure 6 is a side view illustrating three thin plates constituting the carrier. [Figure 7] Figure 7 is a front cross-sectional view showing the main part of the process of grinding a workpiece with the double-sided surface grinding device. [Figure 8] Figure 8 is a front cross-sectional view showing the main part of the process of grinding a workpiece with the double-sided surface grinding device. [Figure 9] Figure 9 is a front cross-sectional view showing the main part of the process of grinding a workpiece with the double-sided surface grinding device. [Figure 10] Figure 10 is a side view when the main part of the process of grinding a workpiece with the double-sided surface grinding device is viewed from the left direction. [Figure 11] Figure 11 is a front cross-sectional view showing the main part of the process of grinding a workpiece with the double-sided surface grinding device. [Figure 12] Figure 12 is a side view when the main part of the double-sided surface grinding device of the first modification is viewed from the left direction. [Figure 13] Figure 13 is a front cross-sectional view showing the main part of the double-sided surface grinding device of the first modification. [Figure 14] Figure 14 is a side view when the main part of the double-sided surface grinding device of the second modification is viewed from the left direction. [Figure 15] Figure 15 is a longitudinal cross-sectional view showing the structure of the carrier of the third modification. [Figure 16] Figure 16 is a side view showing the structure of the carrier body of the third modification. [Figure 17] Figure 17 is a side view when the main part of the double-sided surface grinding device of the third modification is viewed from the left direction. [Figure 18] Figure 18 is a front cross-sectional view showing the main part of the process of grinding a workpiece with the double-sided surface grinding device of the third modification. [Figure 19] Figure 19 is a side view showing the structure of the carrier body in another aspect of the third modification. [Figure 20]Figure 20 is a side view of the main part of a double-ended surface grinding machine in another embodiment of the third modified example, viewed from the left. [Figure 21] Figure 21 is a front cross-sectional view showing the main parts of a double-ended surface grinding machine of the fourth modified example. [Figure 22] Figure 22 is a side view of the main part of the double-ended surface grinding machine of the fourth modified example, viewed from the right. [Figure 23] Figure 23 is a side view showing the main parts of a double-ended surface grinding apparatus according to another embodiment. [Modes for carrying out the invention]

[0023] Hereinafter, exemplary embodiments will be described in detail with reference to the drawings. In the following embodiments, the double-ended surface grinding apparatus according to the present disclosure will be described using a horizontal double-ended surface grinding apparatus as an example. Note that the drawings are for conceptual explanation of the technology of the present disclosure. Therefore, in order to facilitate understanding of the technology of the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified in the drawings.

[0024] 《Embodiment》 The double-ended surface grinding apparatus 1 processes thin plate-shaped workpieces W. In this example, the workpiece W is a semiconductor wafer such as a disc-shaped SiC wafer. Notches may be formed on the outer surface of the workpiece W, or a flat area called an orientation flat may be formed.

[0025] In recent years, semiconductor wafers have tended to become thinner. In particular, SiC wafers used in power semiconductors are about half the thickness of conventional silicon wafers and are extremely thin. The thickness of the workpiece W processed by the double-ended surface grinding apparatus 1 of this embodiment is, for example, less than 600 μm. A specific example of the thickness of the workpiece W is 400 μm.

[0026] -Configuration of a double-ended surface grinding machine- The double-ended surface grinding machine 1 is a grinding machine that holds a workpiece W under static pressure from both sides and grinds the workpiece W by sandwiching it from both sides while rotating the first grinding wheel 91 and the second grinding wheel 95, thereby finishing the grinding surfaces on both sides of the workpiece W to a flat state. The double-ended surface grinding machine 1 is configured in a forced-drive-less system in which the carrier 70 into which the workpiece W is fitted is not rotated.

[0027] The double-ended surface grinding apparatus 1 will be described with reference to Figures 1 to 4. In the following description, terms such as "up," "down," "front," "back," "left," and "right" refer to the direction of the arrows shown in Figures 1 to 4. As shown in Figure 1, the double-ended surface grinding apparatus 1 comprises a workpiece holder 2 and a grinding wheel device 3. The double-ended surface grinding apparatus 1 does not have a drive mechanism for rotating the carrier 70. The workpiece holder 2 and the grinding wheel device 3 are fixed on a horizontal bed 5.

[0028] <Workpiece holding device> The workpiece holding device 2 is a device that holds the workpiece W when grinding both sides of the workpiece W. As shown in Figures 2 to 4, the workpiece holding device 2 comprises an internal case 8, an external case 10, a first workpiece holder 30 and a second workpiece holder 40, a carrier 70, and a slide drive mechanism 9. The first workpiece holder 30 and the second workpiece holder 40 constitute the "pair of workpiece holders" in this embodiment.

[0029] <Internal Case> The internal case 8 surrounds the first workpiece holder 30 and the second workpiece holder 40 and supports the first workpiece holder 30 and the second workpiece holder 40 so that they can move relative to each other. The internal case 8 is formed in the shape of a roughly rectangular box with openings at the top and bottom, and is positioned on the upper side of the external case 10. The external case 10 is formed in the shape of a roughly rectangular box with an opening at the top. The bottom surface of the external case 10 is fixed to the top surface of the bed 5.

[0030] <External Case> A front support section 13 is provided on the front side of the outer case 10. The front support section 13 pivotably supports the inner case 8 at its front. The front support section 13 consists of a pair of support rods 16 and support brackets 17. The pair of support rods 16 are provided on the upper front sides of the left and right side wall plates of the outer case 10, respectively. The support brackets 17 are provided on the left and right front sides of the inner case 8. The support rods 16 are slidably inserted through the support brackets 17.

[0031] A rear support portion 14 is provided on the rear side of the outer case 10. The rear support portion 14 supports the inner case 8 at its rear, allowing for height adjustment. The rear support portion 14 consists of a cam 21, a cam motor 23, and a cam follower 24. The cam motor 23 rotates the cam 21 via a cam shaft 22. The cam follower 24 is provided on the rear side of the inner case 8 and slides against the cam 21. When the cam motor 23 is operated, the cam 21 rotates, causing the position of the cam follower 24 to move up and down.

[0032] A dressing device 25 is located in the lower part of the external case 10. The dressing device 25 dresses the first grinding wheel 93 of the first grinding wheel 91 and the second grinding wheel 97 of the second grinding wheel 95. The dressing device 25 is, for example, detachably fixed to the bed 5.

[0033] <First workpiece holder, second workpiece holder> The first workpiece holder 30 and the second workpiece holder 40 are arranged to face each other in the horizontal direction and are supported by the internal case 8 so as to be movable in the left-right direction. The first workpiece holder 30 and the second workpiece holder 40 are located on both sides in the thickness direction of the workpiece W housed in the housing hole 71 of the carrier 70. The first workpiece holder 30 holds the carrier 70 and is positioned to the left of the carrier 70. The second workpiece holder 40 is positioned to the right of the carrier 70.

[0034] The first workpiece holder 30 includes a first base plate 31 and a first support pad 32. The second workpiece holder 40 includes a second base plate 41 and a second support pad 42. The first base plate 31 and the second base plate 41 are each arranged parallel to a vertical plane in the front-rear direction. The first support pad 32 is provided on the side of the first base plate 31 facing the second base plate 41. The second support pad 42 is provided on the side of the second base plate 41 facing the first base plate 31.

[0035] In Figure 4, only the side views of the first base plate 31 and the first support pad 32 are shown. However, the first base plate 31 and the second base plate 41, and the first support pad 32 and the second support pad 42 have basically the same configuration. Therefore, the side views of the second base plate 41 and the second support pad 42 are omitted from the illustration.

[0036] The first support pad 32 and the second support pad 42 hold the workpiece W from both sides non-contact using the pressure of a fluid such as air or water. The first support pad 32 and the second support pad 42 are formed in a substantially disc shape. Multiple discharge ports 65 for discharging fluid are formed on the opposing surfaces of the first support pad 32 and the second support pad 42. The non-contact workpiece holding achieved by the first support pad 32 and the second support pad 42 is so-called static pressure holding.

[0037] The first support pad 32 further has the function of adsorbing and holding the workpiece W. For example, the first support pad 32 is provided with a vacuum suction chuck. In this case, an adsorption hole for adsorbing the workpiece W is formed on the surface of the first support pad 32 facing the second support pad 42. A vacuum pump means for exerting suction force on the adsorption hole is connected to the first support pad 32. For the means of adsorbing the workpiece W, a known means such as an electrostatic chuck, depending on the material of the workpiece W, can be used.

[0038] A notched first opening 66 is formed on the lower side of both the first support pad 32 and the second support pad 42. The first opening 66 of the first support pad 32 extends from the outer edge of the first support pad 32 to a position slightly beyond the center, and has a partially circular shape, with a straight line cutting through it so that a part of the circle remains in an arc shape, and the cut portion of the partially circular shape is open downwards. The first opening 66 of the second support pad 42 is formed in the same way as the first opening 66 of the first support pad 32.

[0039] The first base plate 31 and the second base plate 41 are substantially rectangular plates with thickness in the left-right direction. A notched second opening 67 is formed on the lower side of each of the first base plate 31 and the second base plate 41. The second opening 67 of the first base plate 31 is formed in a shape corresponding to the first opening 66 of the first support pad 32. The second opening 67 of the second base plate 41 is formed in a shape corresponding to the first opening 66 of the second support pad 42.

[0040] The first opening 66 of the first support pad 32 and the second opening 67 of the first base plate 31 are connected to each other and constitute a first entry point 68 into which the first grinding wheel 91 enters. The first opening 66 of the second support pad 42 and the second opening 67 of the second base plate 41 are connected to each other and constitute a second entry point 69 into which the second grinding wheel 95 enters. The first entry point 68 and the second entry point 69 are in a positional relationship that corresponds to each other in the left-right direction.

[0041] The vertical dimension of the first base plate 31 is approximately equal to the vertical dimension of the first support pad 32, and the front-to-back dimension of the first base plate 31 is greater than the front-to-back dimension of the first support pad 32. The vertical dimension of the second base plate 41 is approximately equal to the vertical dimension of the second support pad 42, and the front-to-back dimension of the second base plate 41 is greater than the front-to-back dimension of the second support pad 42.

[0042] Four support rollers 61 are provided on the surface of the first base plate 31 facing the second workpiece holder 40, and around the first support pad 32. The four support rollers 61 are arranged at approximately equal pitches along the outer circumference of the first support pad 32. Each support roller 61 is prevented from rotating by inserting a rotation-preventing pin or the like. The first base plate 31 may also be provided with a support structure that does not have a rotation function in place of the support rollers 61 to support the carrier 70.

[0043] The first workpiece holder 30 and the second workpiece holder 40 are supported by the internal case 8 by four guide rods 51. Four through holes 52 are formed on both the left and right sides of the first support pad 32 of the first workpiece holder 30 and on both the left and right sides of the second support pad 42 of the second workpiece holder 40. One guide rod 51 is installed each on the front, back, top, and bottom of the internal case 8, and extends horizontally through the interior of the internal case 8. The four guide rods 51 are inserted into the through holes 52 via bushings 53, and support the first workpiece holder 30 and the second workpiece holder 40 so that they can slide horizontally.

[0044] <Career> The carrier 70 is positioned in a space surrounded by four support rollers 61. The outer circumference of the carrier 70 is supported by the four support rollers 61. Because it is held in this manner, the carrier 70 is easy to replace. The carrier 70 is formed in a ring shape that allows the workpiece W to be loosely fitted. The carrier 70 has a circular accommodating hole 71. The accommodating hole 71 is a hole that rotatably accommodates the workpiece W and opens on both sides in the thickness direction of the carrier 70. The workpiece W can be easily fitted into and removed from such an accommodating hole 71.

[0045] As shown in Figure 5, the carrier 70 is composed of a carrier body 72 and a carrier ring 81. The carrier body 72 is a ring-shaped plate with a receiving hole 71. The carrier body 72 has a three-layer structure made up of three thin plates stacked on top of each other. The three thin plates that make up the carrier body 72 are the first side plate 73, the intermediate plate 75, and the second side plate 77 shown in Figure 6. The first side plate 73, the intermediate plate 75, and the second side plate 77 are each metal plates and have the same outer diameter. The first side plate 73 and the second side plate 77 face each other via the intermediate plate 75.

[0046] A circular intermediate hole 76 is formed in the intermediate plate 75. The diameter of the intermediate hole 76 is slightly larger (for example, about 0.5 mm) than the outer diameter of the workpiece W. The center of the intermediate hole 76 and the center of the intermediate plate 75 are approximately coincident. The intermediate hole 76 forms a concentric inner periphery of the outer periphery of the intermediate plate 75. A first side hole 74, which is shaped like a Daruma doll with a semicircle connected to a circular outer periphery, is formed in the first side plate 73. A second side hole 78, which is shaped like a Daruma doll similar to the first side hole 74, is formed in the second side plate 77. The circular portion of the first side hole 74 and the circular portion of the second side hole 78 each have the same diameter as the intermediate hole 76 and are formed at positions corresponding to the intermediate hole 76. The circular portions of the first side hole 74 and the second side hole 78 and the intermediate hole 76 constitute a receiving hole 71.

[0047] The semicircular portion that bulges outwards on the outer circumference of the first side hole 74 exposes the lower part of the intermediate plate 75 from the first side plate 73, forming a crescent-shaped first recess 79. The first recess 79 has the intermediate plate 75 exposed from the first side plate 73 as its bottom surface and opens to the housing hole 71. The semicircular portion that bulges outwards on the outer circumference of the second side hole 78 exposes the lower part of the intermediate plate 75 from the second side plate 77, forming a crescent-shaped second recess 80. The second recess 80 has the intermediate plate 75 exposed from the second side plate 77 as its bottom surface and opens to the housing hole 71.

[0048] The first recess 79 is where the first grinding wheel 91 of the carrier 70 enters. The second recess 80 is where the second grinding wheel 95 enters. The portion of the carrier 70 corresponding to the first recess 79 and the second recess 80 consists only of the intermediate plate 75. The thickness of the intermediate plate 75 is thinner than the finished thickness of the workpiece W, that is, the thickness of the workpiece W after grinding. Therefore, the carrier 70 does not come into contact with the first grinding wheel 91 and the second grinding wheel 95 until the grinding of the workpiece W is complete.

[0049] The thickness of the first side plate 73 and the second side plate 77 are, respectively, equal to or greater than the thickness of the intermediate plate 75. From the viewpoint of holding the workpiece W without it falling out, the thickness of the portion where the first side plate 73, intermediate plate 75, and second side plate 77 of the carrier 70 overlap is preferably 100 μm or more greater than the thickness of the workpiece W. For example, if the thickness of the workpiece W is 400 μm, the thickness of each of the first side plate 73, intermediate plate 75, and second side plate 77 is 200 μm.

[0050] The carrier ring 81 is formed substantially concentrically with the housing hole 71 of the carrier 70 and holds the outer periphery of the first side plate 73, the second side plate 77, and the intermediate plate 75 by clamping them. The carrier 70 is not forcibly rotated. Although not shown, the carrier 70 is fixed in a non-rotatable state by inserting a rotation-restricting pin or the like into the carrier ring 81. The carrier 70 may also be fixed in a non-rotatable state by engaging a rotation-restricting gear in a gear groove formed on the outer circumferential surface of the carrier ring 81. Any configuration can be adopted as a means of fixing the carrier 70 in a non-rotatable state.

[0051] <Slide drive mechanism> As shown in Figures 1 to 3, the slide drive mechanism 9 comprises a first cylinder 35 and a second cylinder 45. The first cylinder 35 is provided to connect the left side wall of the internal case 8 to the first workpiece holder 30 and moves the first workpiece holder 30 in the left-right direction along the guide rod 51. The second cylinder 45 is provided to connect the first workpiece holder 30 and the second workpiece holder 40 and moves the second workpiece holder 40 in the left-right direction along the guide rod 51. The first cylinder 35 and the second cylinder 45 are each composed of, for example, pneumatic cylinders.

[0052] The first cylinder 35 comprises a first cylinder body 36 and a first cylinder rod 37. The right end of the first cylinder body 36 is attached to the left side wall of the internal case 8. The left end of the first cylinder body 36 penetrates the external case 10 and protrudes to the left of the external case 10. The first cylinder rod 37 moves back and forth from the first cylinder body 36, passing through the left side wall of the internal case 8. The tip of the first cylinder rod 37 is attached to the first base plate 31 of the first workpiece holder 30.

[0053] The second cylinder 45 comprises a second cylinder body 46 and a second cylinder rod 47. The left end of the second cylinder body 46 is attached to the second base plate 41 of the second workpiece holder 40. The right end of the second cylinder body 46 penetrates the inner case 8 and the outer case 10 and protrudes to the right outward of the outer case 10. The second cylinder rod 47 moves back and forth from the second cylinder body 46, passing through the second workpiece holder 40. The tip of the second cylinder rod 47 is attached to the first base plate 31 of the first workpiece holder 30.

[0054] The slide drive mechanism 9 moves the first workpiece holder 30 and the second workpiece holder 40 from the "workpiece attachment / detachment position" toward each other when grinding the workpiece W, and holds them in the "workpiece grinding position" where the first support pad 32 and the second support pad 42 are close to each other at approximately the center position in the left-right direction within the internal case 8. The first workpiece holder 30 and the second workpiece holder 40 fix the carrier 70 by sandwiching it in the "workpiece grinding position". The carrier 70 is positioned by being sandwiched between the first workpiece holder 30 and the second workpiece holder 40.

[0055] Furthermore, when attaching or detaching the workpiece W, the slide drive mechanism 9 moves the first workpiece holder 30 and the second workpiece holder 40 in a direction that separates them relatively from the "grinding position," and holds the first workpiece holder 30 and the second workpiece holder 40 in the "workpiece attachment / detachment position" which is separated from each other by a predetermined distance. The carrier 70 moves together with the first workpiece holder 30. Therefore, when the first workpiece holder 30 and the second workpiece holder 40 are in the "workpiece attachment / detachment position," it is possible to insert the workpiece W into the housing hole 71 of the carrier 70 or to remove the workpiece W from the housing hole 71.

[0056] <Grinding device> The grinding wheel device 3 is a device that grinds both sides of a workpiece W held by the workpiece holding device 2. As shown in Figure 1, the grinding wheel device 3 is positioned on both the left and right sides of the workpiece holding device 2. As shown in Figures 7 to 9 and Figure 11, the grinding wheel device 3 comprises a first grinding wheel 91, a first drive motor (not shown), a second grinding wheel 95, and a second drive motor (not shown). The first grinding wheel 91 and the second grinding wheel 95 correspond to the "pair of grinding wheels" in this embodiment. The first drive motor is housed in a spindle case 94, and the second drive motor is housed in a spindle case 98.

[0057] Both the first grinding wheel 91 and the second grinding wheel 95 are configured in a cup shape. The first grinding wheel 91 and the second grinding wheel 95 rotate in the same direction relative to each other by the first drive motor and the second drive motor. The rotation axes Ac of the first grinding wheel 91 and the second grinding wheel 95 coincide in the left-right direction. The first drive motor and the second drive motor rotate the first grinding wheel 91 and the second grinding wheel 95 at the same rotational speed relative to each other. The first drive motor and the second drive motor may rotate the first grinding wheel 91 and the second grinding wheel 95 with a difference in rotational speed.

[0058] The first grinding wheel 91 and the second grinding wheel 95 are positioned on both sides in the thickness direction of the workpiece W housed in the receiving hole 71 of the carrier 70, and are arranged in a positional relationship that faces each other through the workpiece W. The first grinding wheel 91 is positioned to face the left side of the workpiece W fitted into the carrier 70 through the first entry port 68 of the first workpiece holder 30. The second grinding wheel 95 is positioned to face the right side of the workpiece W fitted into the carrier 70 through the second entry port 69 of the second workpiece holder 40.

[0059] Both the first grinding wheel 91 and the second grinding wheel 95 are eccentrically positioned downward with respect to the center C1 of the housing hole 71 of the carrier 70. The first grinding wheel 91 and the second grinding wheel 95 each have an outer diameter larger than the radius of the housing hole 71 of the carrier 70. The outer diameters of the first grinding wheel 91 and the second grinding wheel 95 are equal to or slightly smaller than the radius of the carrier 70.

[0060] The grinding surfaces 90 on the outer circumference of the first grinding wheel 91 and the second grinding wheel 95 correspond to the center C1 of the housing hole 71 of the carrier 70 and contact the workpiece W over its radial range. When the workpiece W fitted into the carrier 70 is viewed from a direction perpendicular to the surface to be ground, the center Cw of the workpiece W coincides with the rotational trajectories of the grinding surfaces of the first grinding wheel 91 and the second grinding wheel 95. An example of the first grinding wheel 91 is shown in Figures 4 and 10. For convenience, in Figures 4 and 10, the center Cw of the workpiece W is shown to coincide with the center C1 of the housing hole 71 (the same applies to Figures 12, 14, 17, 20, 22, and 23 which will be referenced later). When the workpiece W rotates, the entire surface to be ground passes through the areas corresponding to the first grinding wheel 91 and the second grinding wheel 95 and is ground.

[0061] The first grinding wheel 91 comprises a first wheel base 92 and a plurality of first grinding wheels 93. The first wheel base 92 is a metal member formed in an annular shape. The plurality of first grinding wheels 93 are arranged in an annular shape on one side surface (right side) of the first wheel base 92 at equal intervals along the outer circumference. The tip surface of each first grinding wheel 93 constitutes a grinding surface 90. A first drive motor is connected to the other side surface (left side) of the first wheel base 92 via a spindle 99. The first drive motor rotates the first grinding wheel 91.

[0062] The second grinding wheel 95 has a second wheel base 96 and a plurality of second grinding wheels 97. The second wheel base 96 is a metal component similar to that of the first wheel base 92. The plurality of second grinding wheels 97 are arranged in an annular shape on one side (left side) of the second wheel base 96, similar to the first grinding wheel 93 of the first grinding wheel 91. The tip surface of each second grinding wheel 97 constitutes the grinding surface 90. A second drive motor is connected to the other side (right side) of the second wheel base 96 via a spindle 99. The second drive motor rotates the second grinding wheel 95.

[0063] The grinding wheel device 3 is configured to allow the first grinding wheel 91 and the second grinding wheel 95 to move axially (left-right). For example, the first grinding wheel 91 and the second grinding wheel 95 are attached to the tip of a spindle 99. The spindle 99 is made axially movable by a ball screw mechanism. A coolant supply passage is provided in the axial center of the spindle 99. The grinding wheel device 3 supplies coolant to the grinding area of ​​the workpiece W.

[0064] When grinding the workpiece W, the grinding device 3 moves the first grinding wheel 91 into the first entry point 68 of the first workpiece holder 30 and the first recess 79 of the carrier 70, and moves the second grinding wheel 95 into the second entry point 69 of the second workpiece holder 40 and the second recess 80 of the carrier 70, thereby moving the first grinding wheel 91 and the second grinding wheel 95 to a "grinding position" that contacts the grinding surfaces on both sides of the workpiece W (see Figure 9). Furthermore, when attaching or detaching the workpiece W, the grinding device 3 moves the first grinding wheel 91 and the second grinding wheel 95 from the "grinding position" to a predetermined "standby position" (see Figures 7 and 11).

[0065] -Operation of the double-ended surface grinding machine- In the double-ended surface grinding apparatus 1, when grinding a workpiece W, as shown in Figure 7, the first grinding wheel 91 and the second grinding wheel 95 are held in the "standby position," and the first workpiece holder 30 and the second workpiece holder 40 are held in the "workpiece attachment / detachment position." In this state, the workpiece W is loaded between the first workpiece holder 30 and the second workpiece holder 40 by a loader (not shown) and fitted into the housing hole 71 of the carrier 70 for storage. At this time, the workpiece W is held in place by suction from the first support pad 32.

[0066] Furthermore, even if orientation flats or notches are formed on the workpiece W, there is no need to worry about the orientation of these flats or notches when the workpiece W is brought in.

[0067] When the workpiece W is placed in the receiving hole 71 of the carrier 70, the second cylinder 45 is actuated in the direction of retracting the second cylinder rod 47, causing the second workpiece holder 40 to move toward the first workpiece holder 30, and as shown in Figure 8, the first workpiece holder 30 and the second workpiece holder 40 are held in the "workpiece grinding position" where the carrier 70 is sandwiched between the first support pad 32 and the second support pad 42. The carrier 70 is also fixed in the axial direction (left-right direction) by being sandwiched between the first support pad 32 and the second support pad 42.

[0068] Next, the suction of the workpiece W by the first support pad 32 is released. Then, a fluid such as air or water is discharged from the discharge ports 65 of the first support pad 32 and the second support pad 42. The workpiece W is held in a non-contact state in the area outside the grinding positions of the first grinding wheel 91 and the second grinding wheel 95, by receiving the pressure of the fluid discharged from the respective discharge ports 65 of the first support pad 32 and the second support pad 42 on both sides.

[0069] In this state, the first drive motor and the second drive motor are activated to start the rotation of the first grinding wheel 91 and the second grinding wheel 95. The first grinding wheel 91 and the second grinding wheel 95 rotate in the same direction relative to each other. Furthermore, the first grinding wheel 91 and the second grinding wheel 95 move from the "standby position" to approach the grinding surface of the workpiece W. As a result of this operation, as shown in Figure 9, the first grinding wheel 91 enters the first entry port 68 of the first workpiece holder 30 and the first recess 79 of the carrier 70, reaching a "grinding position" where it contacts one of the grinding surfaces of the workpiece W. The second grinding wheel 95 enters the second entry port 69 of the second workpiece holder 40 and the second recess 80 of the carrier 70, reaching a "grinding position" where it contacts the other grinding surface of the workpiece W.

[0070] In this way, the workpiece W is sandwiched from both sides by the first grinding wheel 91 and the second grinding wheel 95, which are rotating in the same direction as the workpiece W in the "grinding position," and grinding of the workpiece W begins. When grinding of the workpiece W begins, as shown in Figure 10, grinding resistance (force in the direction indicated by the triangular arrow in the enlarged view of Figure 10) is applied to the workpiece W from the first grinding wheel 91 and the second grinding wheel 95, and a moment in the same rotational direction Dr as the rotational direction Dr of the first grinding wheel 91 and the second grinding wheel 95 acts on the workpiece W. Due to this moment, the workpiece W rotates in the same direction as the first grinding wheel 91 and the second grinding wheel 95 while following the inner circumference of the housing hole 71. At this time, since the housing hole 71 of the carrier 70 is circular, the workpiece W rotates smoothly without getting caught. Then, when grinding of the workpiece W is continued for a predetermined time, both sides of the workpiece W are ground over their entire surface by the first grinding wheel 91 and the second grinding wheel 95.

[0071] When grinding of the workpiece W is complete, the first grinding wheel 91 and the second grinding wheel 95 are moved from the "grinding position" to the "retracted position," as shown in Figure 11. The second workpiece holder 40 is also moved from the "workpiece grinding position" to the "workpiece attachment / detachment position." Then, the ground workpiece W is removed from the carrier 70 and transported away by a loader (not shown).

[0072] -Features of the Embodiment- In this embodiment of the double-ended surface grinding apparatus 1, the workpiece W is rotatably housed in a housing hole 71 of the carrier 70. The first grinding wheel 91 and the second grinding wheel 95 rotate in the same direction relative to each other and contact the grinding surfaces on both sides of the workpiece W. The workpiece W rotates along the inner circumference of the housing hole 71 due to the moment generated by the grinding resistance received from the first grinding wheel 91 and the second grinding wheel 95. At this time, the carrier 70 is fixed so as not to rotate. In other words, the workpiece W is not forced to rotate together with the carrier 70. Therefore, stress does not concentrate on a part of the workpiece W as in the conventional configuration in which the workpiece W is fitted and supported by the carrier 70, and damage to the workpiece W can be suppressed. Furthermore, since the carrier 70 does not rotate when the workpiece W is ground, the parts of the carrier 70 other than those corresponding to the first grinding wheel 91 and the second grinding wheel 95 can be made relatively thick with a three-layer structure, making the carrier 70 less likely to bend during grinding of the workpiece W. This allows the workpiece W to be held stably within the carrier 70.

[0073] In this embodiment of the double-ended surface grinding apparatus 1, a first recess 79 and a second recess 80 are formed on both sides of the carrier 70. The first recess 79 and the second recess 80 are open to the housing hole 71. The first grinding wheel 91 enters into the first recess 79. The second grinding wheel 95 enters into the second recess 80. Since the thickness of the parts of the carrier 70 corresponding to the first recess 79 and the second recess 80 is thinner than the thickness of the workpiece W, the first grinding wheel 91 entering into the first recess 79 and the second grinding wheel 95 entering into the second recess 80 can each contact the corresponding surface to be ground on the workpiece W and grind that surface. The parts of the carrier 70 other than the parts into which the first grinding wheel 91 and the second grinding wheel 95 enter can be made thicker without considering interference with the first grinding wheel 91 and the second grinding wheel 95. This increases the rigidity of the carrier 70, making it less likely to bend during grinding of the workpiece W.

[0074] In this embodiment of the double-ended surface grinding apparatus 1, the carrier 70 is fixed by being sandwiched between the first workpiece holder 30 and the second workpiece holder 40. This makes the carrier 70 less prone to bending during grinding of the workpiece W, and allows the workpiece W to be held stably within the carrier 70. Furthermore, when supporting the workpiece W without contact, the positioning of the first workpiece holder 30 and the second workpiece holder 40 can be performed by sandwiching the carrier 70. Therefore, it is not necessary to provide a positioning mechanism such as a stopper for positioning the first workpiece holder 30 and the second workpiece holder 40, and the configuration of the double-ended surface grinding apparatus 1 can be simplified.

[0075] 《First variation》 In this first modified double-ended surface grinding apparatus 1, the shapes of the first recess 79 and the second recess 80 of the carrier 70 differ from those of the above embodiment. In the double-ended surface grinding apparatus 1 of the above embodiment, the thickness of the parts of the carrier 70 corresponding to the first recess 79 and the second recess 80 is relatively thin, which may cause bending in those parts. In contrast, the carrier 70 of this example has a configuration that addresses this issue.

[0076] As shown in Figure 12, the first recess 79 in this example is an arc-shaped groove (for convenience, the first recess 79 is dot-hatched in Figure 12). The first recess 79 extends to correspond to the trajectory through which the first grinding wheel 93 passes as the first grinding wheel 91 rotates, and both ends in the longitudinal direction are open to the housing hole 71. The second recess 80 in this example is an arc-shaped groove, similar to the first recess 79, and extends to correspond to the trajectory through which the second grinding wheel 97 passes as the second grinding wheel 95 rotates, and both ends in the longitudinal direction are open to the housing hole 71.

[0077] As shown in Figure 13, a first side plate 73 is laminated to the intermediate plate 75 on the side of the first recess 79 to the housing hole 71. In a side view of the carrier 70 from the left, the first side plate 73 is joined to the intermediate plate 75 in the area enclosed by the first recess 79 and the housing hole 71 of the carrier 70, and constitutes the inner circumferential surface of the housing hole 71 on the side of the first recess 79. In addition, a second side plate 77 is laminated to the intermediate plate 75 on the side of the second recess 80 to the housing hole 71. In a side view of the carrier 70 from the right, the second side plate 77 is joined to the intermediate plate 75 in the area enclosed by the second recess 80 and the housing hole 71 of the carrier 70, and constitutes the inner circumferential surface of the housing hole 71 on the side of the second recess 80.

[0078] In this first modified double-ended surface grinding apparatus 1, the first recess 79 is an arc-shaped groove formed to avoid interference with the first grinding wheel 93 of the first grinding wheel 91. The second recess 80 is an arc-shaped groove formed to avoid interference with the second grinding wheel 97 of the second grinding wheel 95. In a carrier 70 having such a first recess 79 and second recess 80, the portion of the first recess 79 located on the side of the housing hole 71 can be made thicker to the extent that it does not interfere with the first grinding wheel 91, and the portion of the second recess 80 located on the side of the housing hole 71 can be made thicker to the extent that it does not interfere with the second grinding wheel 95. This is advantageous for increasing the rigidity of the carrier 70.

[0079] In this first modified double-ended surface grinding apparatus 1, the first side plate 73 is also provided on the side of the housing hole 71 of the first recess 79, forming the inner circumferential surface of the housing hole 71 on the side of the first recess 79. The second side plate 77 is also provided on the side of the housing hole 71 of the second recess 80, forming the inner circumferential surface of the housing hole 71 on the side of the second recess 80. This allows for a relatively wide inner circumferential surface of the housing hole 71 on both the first recess 79 and the second recess 80 sides. This, along with the increased rigidity of the carrier 70, is advantageous in suppressing the detachment of the workpiece W from the carrier 70 during grinding.

[0080] 《Second variation》 In this second modified double-ended surface grinding apparatus 1, the position of the housing hole 71 of the carrier 70 differs from that of the above embodiment, and the rotation direction Dr of the first grinding wheel 91 and the second grinding wheel 95 is determined by the positional relationship of the housing hole 71 in the carrier 70. The double-ended surface grinding apparatus 1 in this example adopts a configuration that is preferable when the housing hole 71 is provided eccentrically with respect to the center C2 of the carrier 70.

[0081] As shown in Figure 14, the housing hole 71 in this example is formed towards the front of the carrier 70. Specifically, the center C1 of the housing hole 71 is located on one side in the front-to-back direction perpendicular to the vertical reference line Lr, which in this example is the front side. The reference line Lr is defined as a straight line passing through the center C2 of the carrier 70 and the rotation centers C3 of the first grinding wheel 91 and the second grinding wheel 95, which are positioned at the grinding position of the workpiece surface W, in a front view of the housing hole 71. The rotation center C3 corresponds to the position of the rotation axis Ac of the first grinding wheel 91 and the second grinding wheel 95.

[0082] In this example, the rotation direction Dr of the first grinding wheel 91 and the second grinding wheel 95 during grinding of the workpiece W is, at the point where they pass the reference line Lr on the surface to be ground, from one side to the other where the center C1 of the housing hole 71 is located in the front-to-back direction perpendicular to the reference line Lr; in this example, it is from the front to the rear. The workpiece W rotates in the same rotation direction Dr as the first grinding wheel 91 and the second grinding wheel 95, following the inner circumference of the housing hole 71, due to the moment generated by the grinding resistance received from the first grinding wheel 91 and the second grinding wheel 95, and both sides of the workpiece surface are ground by the first grinding wheel 91 and the second grinding wheel 95.

[0083] In this second modified double-ended surface grinding apparatus 1, the center C1 of the housing hole 71 is located in front of the reference line Lr. The workpiece W housed in this housing hole 71 is unevenly distributed on the front side of the carrier 70. The first grinding wheel 91 and the second grinding wheel 95 rotate in a direction perpendicular to the reference line Lr, from the front side to the rear side where the center C1 of the housing hole 71 is located, at the point where they pass the reference line Lr on the surface to be ground. This makes it possible to suppress damage to the workpiece W due to the grinding operation compared to when the rotation directions Dr of the first grinding wheel 91 and the second grinding wheel 95 are in opposite directions.

[0084] 《Third variation》 In this third modified double-ended surface grinding apparatus 1, the configuration of the carrier 70 differs from that of the above embodiment. The double-ended surface grinding apparatus 1 in this example employs a configuration in which the finished thickness of the workpiece W (thickness of the workpiece W after grinding) does not depend on the thickness of the carrier 70. This double-ended surface grinding apparatus 1 is suitable when there are no notches on the outer circumferential surface of the workpiece W to be processed, or when the notches formed on the outer circumferential surface of the workpiece W are notches in a relatively narrow area, such as a notch.

[0085] As shown in Figures 15 and 16, the carrier body 72 is a single-plate structure and consists of a single metal plate. The carrier body 72 may also be made of a resin plate. An opening 85 including a housing hole 71 is formed in the carrier body 72. The opening 85 is formed in a roughly keyhole shape with a semicircular shape connected to a circular outer circumference. The housing hole 71 is formed by the circular portion of the opening 85. The semicircular portion that bulges outward on the outer circumference of the housing hole 71 penetrates the carrier body 72 in the thickness direction together with the housing hole 71 and forms a relief hole 86 that allows the carrier body 72 to escape from the first grinding wheel 91 and the second grinding wheel 95.

[0086] As shown in Figures 17 and 18, when grinding both sides of the workpiece W, the first grinding wheel 91 and the second grinding wheel 95 enter the relief hole 86 from both sides in the thickness direction of the workpiece W and contact the surface to be ground. The relief hole 86 expands the housing hole 71 outward and opens to the housing hole 71. The width w1 of the open end of the relief hole 86 is, for example, about the same as or less than the radius of the housing hole 71. The width w1 of the open end of the relief hole 86 may be greater than the radius of the housing hole 71, as long as it is less than the diameter of the housing hole 71.

[0087] The thickness of the carrier body 72 is preferably greater than the thickness of the workpiece W to prevent the workpiece W from falling off. For example, if the thickness of the workpiece W is 400 μm, the thickness of the carrier body 72 is 600 μm. As shown in Figure 19, the opening 85 of the carrier body 72 may be formed in a Daruma shape with fan shapes connected to a circular outer circumference. In this case, the fan-shaped portion that bulges outwards on the outer circumference of the opening 85 constitutes a relief hole 86. As shown in Figure 20, when grinding both sides of the workpiece W, the first grinding wheel 91 and the second grinding wheel 95 enter the relief hole 86 from both sides in the thickness direction of the workpiece W and contact the surface to be ground.

[0088] In this third modified double-ended surface grinding apparatus 1, relief holes 86 are formed in the carrier 70. The first grinding wheel 91 and the second grinding wheel 95 each enter the relief holes 86 and contact the surface to be ground, so that even if the thickness of the workpiece W is thinner than the thickness of the carrier 70 (more precisely, the carrier body 72), the workpiece W can be ground to a predetermined finished thickness. Therefore, even extremely thin workpieces W of 100 μm or less can be ground. In addition, the carrier 70 can be made thicker without considering interference with the first grinding wheel 91 and the second grinding wheel 95. This increases the rigidity of the carrier 70, making it less likely to bend during grinding of the workpiece W.

[0089] In this third modified double-ended surface grinding apparatus 1, an opening 85 consisting of a accommodating hole 71 and a relief hole 86 is formed to penetrate the carrier body 72. This allows the carrier body 72 to be constructed from a single metal plate, eliminating the need to use multiple thin plates for the carrier body 72. Furthermore, while constructing a carrier body 72 having a first recess 79 and a second recess 80 as in the above embodiment using a single metal plate requires machining to form the first recess 79 and the second recess 80 on the metal plate, this example does not require such machining, allowing the carrier 70 to be manufactured inexpensively and easily. In addition, there is a high degree of freedom in selecting the material and composition of the carrier body 72. Moreover, by having the relief hole 86 penetrate the carrier body 72, the risk of contact between the grinding surfaces 90 of the first grinding wheel 91 and the second grinding wheel 95 and the carrier body 72 can be reduced.

[0090] 《Fourth variation》 In this fourth modified double-ended surface grinding apparatus 1, the configuration of the carrier 70 and the configurations of the first workpiece holder 30 and the second workpiece holder 40 differ from those of the above embodiment. The double-ended surface grinding apparatus 1 in this example employs a configuration that suppresses the deflection of the carrier 70 during grinding of the workpiece W, even if the entire carrier 70 is thinner than the workpiece W.

[0091] As shown in Figure 21, the carrier body 72 is a single-plate structure and consists only of a plate material corresponding to the intermediate plate 75 in the above embodiment. The carrier body 72 is made of, for example, a single metal plate. The carrier body 72 may also be made of a resin plate material. The thickness of the carrier body 72 in this example is thinner than the workpiece W throughout. For example, if the thickness of the workpiece W is 400 μm, the thickness of the carrier 70 is 200 μm.

[0092] The first workpiece holder 30 and the second workpiece holder 40 clamp and fix the carrier 70 (carrier body 72) in the "workpiece grinding position". Specifically, a first protrusion 33 is provided on the surface of the first support pad 32 facing the carrier 70. As shown in Figure 22, the first protrusion 33 extends from the midpoint in the radial direction of the first support pad 32 towards the outer circumference, covering the entire area except for the first opening 66 which forms the first entry point 68 in the circumferential direction of the first support pad 32, and is formed in a roughly C-shape (for convenience, the first protrusion 33 is shown with dot hatching in Figure 22).

[0093] Furthermore, a second protrusion 43 is provided on the surface of the second support pad 42 facing the carrier 70. Similar to the first protrusion 33, the second protrusion 43 extends from the midpoint in the radial direction of the second support pad 42 towards the outer circumference, covering the entire area except for the first opening 66 which forms the second entry point 69 in the circumferential direction of the second support pad 42, and is formed in a substantially C-shape. When the first workpiece holder 30 and the second workpiece holder 40 are in the "workpiece grinding position", the first protrusion 33 and the second protrusion 43 contact the carrier 70.

[0094] The height of the first protrusion 33 is such that, when the first protrusion 33 is in contact with the carrier 70, there is a gap between the first support pad 32 and the workpiece W housed in the housing hole 71. The height of the second protrusion 43 is such that, when the second protrusion 43 is in contact with the carrier 70, there is a gap between the second support pad 42 and the workpiece W housed in the housing hole 71. As a result, the first workpiece holder 30 and the second workpiece holder 40 do not simultaneously contact the workpiece W in the "workpiece grinding position," but the first protrusion 33 and the second protrusion 43 clamp and fix the carrier 70 (see Figure 21).

[0095] In this fourth modified double-ended surface grinding apparatus 1, the carrier 70 is held and fixed by the first workpiece holder 30 and the second workpiece holder 40. As a result, even if the carrier 70 is thinner than the workpiece W, the carrier 70 is less likely to bend during grinding of the workpiece W. Therefore, the workpiece W can be held stably within the carrier 70, and the grinding surfaces on both sides of the workpiece W can be suitably ground.

[0096] Other embodiments In the above embodiment, the outer diameters of the first grinding wheel 91 and the second grinding wheel 95 are assumed to be approximately the same as the radius of the carrier 70, but this is not limited to this. The outer diameters of the first grinding wheel 91 and the second grinding wheel 95 may be any diameter greater than or equal to the radius of the workpiece W.

[0097] For example, as shown in Figure 23, the outer diameters of the first grinding wheel 91 and the second grinding wheel 95 may be reduced to the extent that grinding resistance can be applied to rotate the workpiece W from the first grinding wheel 91 and the second grinding wheel 95. This reduces the area of ​​the first recess 79 and the second recess 80. In other words, the relatively thin portion consisting only of the intermediate plate 75 of the carrier 70 can be reduced. As a result, the rigidity of the carrier 70 can be increased, making it less likely for the carrier 70 to bend during grinding of the workpiece W.

[0098] In the above embodiment, the first workpiece holder 30 and the second workpiece holder 40 are shown to sandwich and fix the carrier 70 at the "workpiece grinding position," but this is not limited to this. For example, the first workpiece holder 30 and the second workpiece holder 40 may each have a gap between them and the carrier 70 at the "workpiece grinding position" that is sufficient to prevent the workpiece W from falling out.

[0099] In the above embodiment, the carrier body 72 is assumed to have a three-layer structure formed by stacking three thin plates, but it is not limited to this. For example, the carrier body 72 may be made of a single metal plate with the first recess 79 and the second recess 80 formed by processing both sides. Alternatively, the carrier body 72 may be made of a synthetic resin that has heat resistance and wear resistance.

[0100] In the above embodiment, the carrier 70 is supported on its outer circumference by four support rollers 61 provided on the first workpiece holder 30, but it is not limited to this. For example, the carrier 70 may be fixed to the first workpiece holder 30 by bolts or the like.

[0101] The double-ended surface grinding device 1 may be switchable between a mode in which the carrier 70 is forcibly rotated and a mode in which the carrier 70 is fixed in a non-rotatable state. For example, the device may be configured such that a gear meshes with a gear groove formed on the outer circumferential surface of the carrier ring 81. In the mode in which the carrier 70 is fixed in a non-rotatable state, the carrier ring 81 is fixed with a rotation-preventing pin, while in the mode in which the carrier 70 is forcibly rotated, the rotation-preventing pin is removed from the carrier ring 81 and the gear is rotated by a motor.

[0102] In the above embodiment, the workpiece W rotates in the same direction as the first grinding wheel 91 and the second grinding wheel 95 during grinding, but this is not limited to this. The direction of rotation of the workpiece W is determined by various factors, such as the positional relationship between the first grinding wheel 91 and the second grinding wheel 95 and the workpiece W during grinding, and the way in which the first grinding wheel 91 and the second grinding wheel 95 contact the workpiece W. Therefore, the workpiece W may rotate in the opposite direction to the first grinding wheel 91 and the second grinding wheel 95. In short, the first grinding wheel 91 and the second grinding wheel 95, which are rotating in the same direction, should contact the surfaces to be ground on both sides of the workpiece W, thereby rotating the workpiece W within the housing hole 71 and grinding the entire circumference of the surface to be ground.

[0103] In the above embodiment, a semiconductor wafer was given as an example of the workpiece W to be processed by the double-ended surface grinding apparatus 1, but it is not limited to this. A semiconductor wafer is merely one example of a workpiece W; any thin, plate-like workpiece W that can rotate while housed in the accommodation hole 71 of the carrier 70 can be processed, such as a metal plate or a ceramic plate.

[0104] In the above embodiment, a horizontal double-ended surface grinding device was used as an example of the double-ended surface grinding device 1, but the invention is not limited thereto. The technology of this disclosure can also be applied to a vertical double-ended surface grinding device in which the first grinding wheel 91 and the second grinding wheel 95 face each other in the vertical direction.

[0105] As described above, preferred embodiments have been explained as examples of the technology of this disclosure. However, the technology of this disclosure is not limited thereto and can be applied to embodiments that are modified, replaced, added to, or omitted as appropriate. It will be understood by those skilled in the art that various further modifications are possible to the above embodiments without departing from the spirit of the technology of this disclosure, and that such modifications also fall within the scope of the technology of this disclosure.

[0106] Furthermore, the designations "First," "Second," etc., in this specification are used to distinguish between the terms to which these designations are attached, and do not limit the number or order of such terms. [Industrial applicability]

[0107] As described above, this disclosure is useful for double-ended surface grinding machines. [Explanation of Symbols]

[0108] 1. Double-ended surface grinding machine 30. First workpiece holder (workpiece holder) 40. Second workpiece holder (workpiece holder) 70 Carriers 71 containment holes 79. First recess (recess) 80 Second recess (recess) 86 Relief hole 91. First grinding wheel (grinding wheel) 92. First wheel base (wheel base) 93. First whetstone (whetstone) 95. Second grinding wheel (grinding wheel) 96. Second wheel base (wheel base) 97. Second whetstone (whetstone) Center of the C1 containment hole C2 is the core of the carrier C3 Rotation center of the first and second grinding wheels Dr. Rotation direction of the first grinding wheel and the second grinding wheel. Lr reference line Double job

Claims

1. A carrier having a circular housing hole formed therein for rotatably housing a thin plate-shaped workpiece, A pair of workpiece holders are located on both sides in the thickness direction of the workpiece housed in the aforementioned housing hole, and hold the workpiece non-contact by fluid pressure, The workpiece held by the pair of workpiece holders is positioned on both sides of the workpiece and is eccentric with respect to the center of the housing hole, comprising: The pair of grinding wheels rotate in the same direction relative to each other and contact the surfaces to be ground on both sides of the workpiece, while the carrier is fixed in a non-rotatable position, thereby rotating the workpiece within the housing hole and grinding the surfaces to be ground. A double-ended surface grinding device characterized by the following features.

2. In the double-ended surface grinding apparatus according to claim 1, On both sides of the carrier, recesses are formed that open to the receiving holes. The grinding wheel enters the recess and contacts the surface to be ground. A double-ended surface grinding device characterized by the following features.

3. In the double-ended surface grinding apparatus according to claim 2, The grinding wheel comprises a wheel base and a grinding wheel provided in an annular shape on one side of the wheel base. The recess is an arc-shaped groove that extends to correspond to the trajectory through which the grinding wheel passes as the grinding wheel rotates, and both ends in the longitudinal direction are open to the housing hole. A double-ended surface grinding device characterized by the following features.

4. In the double-ended surface grinding apparatus according to claim 1, The carrier has a relief hole formed in which the housing hole is expanded toward the outer circumference and is open to the housing hole. The grinding wheel enters the relief hole and comes into contact with the surface to be ground. A double-ended surface grinding device characterized by the following features.

5. In the double-ended surface grinding apparatus according to any one of claims 1 to 4, In a front view of the housing hole, if a straight line passing through the center of the carrier and the rotation center of the grinding wheel positioned at the grinding position of the surface to be ground is defined as the reference line, then the center of the housing hole is located on one side of the reference line in a direction perpendicular to the reference line. The rotation direction of the grinding wheel is from one side to the other, where the center of the housing hole is located in a direction perpendicular to the reference line at the point where it passes the reference line on the surface to be ground. A double-ended surface grinding device characterized by the following features.

6. In the double-ended surface grinding apparatus according to any one of claims 1 to 4, The pair of workpiece holders secure the carrier by sandwiching it. A double-ended surface grinding device characterized by the following features.

Images