Patent Grant
9889532
The present invention relates to double disc surface grinding machines and grinding methods, and more specifically, to a double disc surface grinding machine and a grinding method for grinding two surfaces of middle- and large-sized annular or generally annular works such as piston rings for large marine vessel engines, inner and outer rings of cross roller bearings for rotary tables in machine tools, and inner and outer rings of large bearings in wind-driven power generators.
Double disc surface grinding machines are conventionally employed to grind works. For example, Patent Literature 1 discloses a double disc surface grinding machine, in which a work has a center hole, where an in-hole driven roller is disposed, and a drive roller and an outer circumferential driven roller are disposed on an outer circumference of the work, whereby the work is held sandwiched by the rollers while being rotatably supported. With this arrangement, a rotating upper wheel and a rotating lower wheel are fed to the work from above and below, and both surfaces of the work is ground simulataneously.
Patent Literature 1: JP-A 2002-96262
When this grinding apparatus simultaneously grinds both surfaces of a large object, such as a piston ring, or an inner or an outer ring of a bearing which has a diameter of approximately 500 mm through 1200 mm, the work moves spontaneously with respect to the in-hole driven roller, the drive roller and the outer circumferential driven roller in a direction in which the pair of grinding wheels are opposed to each other (i.e., in an axial thickness direction of the work). In other words, the work is sandwiched and is supported rotatably by the rollers, and because of this the work moves with respect to each roller, and as a result, the work also moves spontaneously in the direction in which the pair of grinding wheels are opposed to each other during the grinding operation. Consequently therefore, if the work has a warp which may look a mountain-shape or an s-shape as shown in
When grinding a large, thin-walled work with the grinding apparatus according to Patent Literature 1, all of the three rollers, i.e., the in-hole driven roller, the drive roller and the outer circumferential driven roller are substantially aligned on a single straight line. In other words, work supporting points are eccentrically-located, and it is not possible to hold the work stably.
Therefore, a primary object of the present invention is to provide a double disc surface grinding machine capable of holding various works stably and grinding them at a high grinding accuracy, and a grinding method therefor.
According to an aspect of the present invention, there is provided a double disc surface grinding machine for grinding two main surfaces of an annular work. The machine includes a pair of rotary grinding wheels opposed to and spaced from each other in a first direction; a rotation shaft extending in the first direction; a work holding section for holding an inner circumferential surface of the work at a plurality of locations; a position adjustment section connecting the rotation shaft and the work holding section to each other for adjusting a position of the work holding section radially of the rotation shaft; a rotation-driving section for integrally rotating the rotation shaft, the position adjustment section, the work holding section and the work around the rotation shaft while the inner circumferential surface of the work is held by the work holding section; and a grinding wheel feeding section for feeding at least one of the grinding wheels to the work so as to sandwich part of the rotating work between the pair of grinding wheels threreby grinding two main surfaces of the work.
According to another aspect of the present invention, there is provided a method of grinding two main surfaces of an annular work with a pair of rotating grinding wheels opposed to each other in a first direction at a space therebetween. The method includes a holding step of holding an inner circumferential surface of the work at a plurality of locations with a work holding section; a rotating step of rotating the work holding section and the work integrally with each other around a rotation shaft which extends in the first direction; and a grinding wheel infeeding step of sandwiching part of the rotating work between the pair of grinding wheels and advancing at least one of the grinding wheels to grind two main surfaces of the work.
According to the invention described above, the inner circumferential surface of the work is held by the work holding section so that the work will not move with respect to the work holding section (in other words, the work will move integrally with the work holding section) during the grinding. Therefore, it is possible to decrease movement of the work with respect to the work holding section in the direction in which the pair of grinding wheels are opposed to each other, during the grinding. Also, the work holding section does not hold any of the two main surfaces (surfaces to be ground) of the work. Therefore, even if there is a warp in the work's surfaces which are to be ground, it is possible to decrease flailing movement of the work during grinding. Further, it is possible to adjust the position of the work holding section in the radial direction of the rotation shaft. This allows to move the work holding section until it makes contact with the inner circumferential surface of the work at a plurality of locations, regardless of the diameter or shape of the inner circumferential surface of the work, and therefore to reliably hold the inner circumferential surface of the work with the work holding section. As a result, it is possible to stably hold the work of a various kinds and achieve good grinding accuracy.
Preferably, the work holding section includes a plurality of holding members extending radially as viewed from the rotation shaft; and each of the holding members is movable radially inward and outward of the rotation shaft, and is contactable to the inner circumferential surface of the work. In this case, since a plurality of holding members which extend radially as viewed from the rotation shaft hold the inner circumferential surface of the work, only a small holding force (a pushing force exerted from the holding member onto the inner circumferential surface of the work) is sufficient at each location of contact on the inner circumferential surface of the work. Also, the holding members may simply be advanced or retracted radially of the rotation shaft to establish easily contact of the holding members with the inner circumferential surface of the work.
Further preferably, the position adjustment section is arranged to allow individual position adjustment of each of the holding members. In this case, position adjustment with respect to the inner circumferential surface of the work can be made individually for each of the holding members. Therefore, it is possible to hold the inner circumferential surface of the work suitably regardless of the kind of the work.
Further, preferably, the position adjustment section is arranged to allow simultaneous position adjustment of the plurality of holding members. In this case, it is possible to perform position adjustment of a plurality of the holding members in a single operation. Therefore, it is possible to perform a task of holding the inner circumferential surface of the work with the plurality of holding members, within a short time.
Preferably, the plurality of holding members include at least a first holding member, a second holding member and a third holding member, which satisfy the following condition that: in the work's inner circumferential surface, with a first location which is defined as a location contacted by the first holding member, a second location which is defined as a location contacted by the second holding member, and a third location which is defined as a location contacted by the third holding member, the second location and the third location are on an opposite side from the side where the first location is, with respect to the rotation shaft; whereas the second location and the third location are on mutually opposite sides from each other with respect to a straight line which passes through the first location and the center of the rotation shaft. In this case, the first holding member, the second holding member and the third holding member are pressed onto the inner circumferential surface of the work. This makes it possible to hold the work by pressing it with a sufficient amount of force with the first holding member, the second holding member and the third holding member. With respect to the rotation shaft as a reference, the second location and the third location are on an opposite side from the first location. In this case, a force applied from the first holding member to the work and forces applied from the second holding member and the third holding member respectively to the work at least include components acting in directions away from each other. Further, with respect to the straight line which passes through the first location and the center of the rotation shaft, the second location and the third location are on mutually opposite sides from each other. In this case, a force applied from the second holding member to the work and a force applied from the third holding member to the work at least include components acting in directions away from each other. As a result of these, it is possible to hold the work more stably.
Further preferably, the rotation shaft and the work are concentric with each other. In this case, it is possible to perform position adjustment of the work holding section with the position adjustment section, and holding of the inner circumferential surface of the work more smoothly.
It should be noted here that in the present invention, the term two main surfaces of the work means a pair of surfaces which connect to the inner circumferential surface of the work. For example, if the work is circular-annular, the two main surfaces of the work refer to a pair of circular-annular surfaces (in other words, two surfaces of the work other than the outer circumferential surface and the inner circumferential surface).
The above-described object and other objects, characteristics, aspects and advantages of the present invention will become clearer from the following detailed description of embodiments of the present invention to be made with reference to the attached drawings.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Referring to
The pair of grinding wheels 16a, 16b are supported by the grinding wheel shafts 18a, 18b. The grinding wheel shafts 18a, 18b are supported by the grinding wheel shaft units 20a, 20b rotatably and movably in a horizontal direction, and are driven by the drive motors 24a, 24b via belts 22a, 22b. Therefore, rotational driving forces from the drive motors 24a, 24b are transmitted via the belts 22a, 22b, to the grinding wheel shafts 18a, 18b, whereby the grinding wheels 16a, 16b are rotated.
The grinding wheel shafts 18a, 18b are each movable horizontally by grinding wheel feeding sections 26a, 26b. As the grinding wheel shafts 18a, 18b are moved horizontally by the grinding wheel feeding sections 26a, 26b, the pair of grinding wheels 16a, 16b are moved horizontally. The bed column 12 has an upper surface, at a center region of which there is provided a lid 28 which is openable/closable.
The bed column 12 has a front surface, where a front bed 30 is disposed. The front bed 30 supports a transport section 32 and a rotation-driving section 34.
The transport section 32 includes a pair of guide rails 36a, 36b, a work table 38, a table mover screw 40 and a drive motor 42. The pair of guide rails 36a, 36b is formed to extend in a fore-aft direction on the front bed 30. In other words, the pair of guide rails 36a, 36b are disposed to cross at right angles with the grinding wheel shafts 18a, 18b. The work table 38 is disposed slidably on the pair of guide rails 36a, 36b. The table mover screw 40 is connected to a lower surface of the work table 38. The drive motor 42 is connected to the table mover screw 40. When the drive motor 42 is driven, the table mover screw 40 is rotated, whereby the work table 38 is slid on the guide rails 36a, 36b, moving closer to or away from the bed column 12. The arrangement makes the work W movable to and away from the pair of grinding wheels 16a, 16b. The rotation-driving section 34 is disposed on the work table 38, and includes a drive motor 44. At an end region of the rotation-driving section 34, a rotation shaft 46 extends in the arrow H direction to rotate the work W. The rotation-driving section 34 is driven by the drive motor 44, and rotates the rotation shaft 46 to rotate the work W.
Referring to
The screw ring 49 is attached to a base flange 56. The base flange 56 is substantially hollow and disc-like. The base flange 56 has a circular hollow portion 58 to which the screw ring 49 is fitted and a plurality (twelve, in the present embodiment) of guide grooves 60 each formed to correspond to (in line with) one of the screw holes 54 in the screw ring 49. Each of the guide grooves 60 extends radially (in a radial direction) of the base flange 56. The plurality of guide grooves 60 are disposed substantially equidistantly in a circumferential direction of the base flange 56. In other words, the base flange 56 has a plurality (twelve, in the present embodiment) of protrusions 61 formed substantially equidistantly in the circumferential direction of the base flange 56, and the guide grooves 60 are formed between mutually adjacent ones of the protrusions 61. While the cylindrical section 50 of the screw ring 49 is fitted to the hollow portion 58, the flange section 52 of the screw ring 49 is attached to the base flange 56 with fasteners 62. Then, the base flange 56, to which the screw ring 49 is attached, is fixed to a shaft end region of the rotation shaft 46 (to the disc section 48) with a plurality (four, in the present embodiment) of fasteners 64. In this state, the rotation shaft 46, the screw ring 49 and the base flange 56 are coaxial with each other and rotatable simultaneously. A work holding section 65 is disposed in the base flange 56. The work holding section 65 includes a plurality (twelve, in the present embodiment) of strip-like holding members 66. Each holding member 66 is fitted into the guide groove 60 of the base flange 56 so that it can slide accurately, and is disposed radially (in a radial direction) of the base flange 56. The plurality of holding members 66 are disposed substantially equidistantly in a circumferential direction of the base flange 56. Also, in order to prevent the holding members 66 from being ground by the grinding wheels 16a, 16b, each holding member 66 has a thickness which is thinner than an axial thickness T of the work W. The holding member 66 on the guide groove 60 is sandwiched by the base flange 56 and a guide plate 68. The guide plate 68 is attached to the base flange 56 with fasteners 70. The guide plate 68 as described above guides the holding member 66 to slide smoothly, without rattling or moving out of the guide groove 60. Adjustment screws 72 are threaded into the screw holes 54 in the screw ring 49. The adjustment screw 72 is disposed in line with the holding member 66 so that a head portion of the adjustment screw 72 can push an end of the holding member 66. By rotating (clockwise or counterclockwise) the adjustment screws 72 with a jig such as a torque wrench, the adjustment screws 72 and the holding members 66 can be moved radially outward/inward of the rotation shaft 46 with respect to an inner circumferential surface of the work W. The adjustment screws 72 are driven to move in the circumferential direction thereby pushing the holding members 66 outward until tip portions of the holding members 66 make pressing contact onto the inner circumferential surface of the work W. By doing so, the inner circumferential surface of the work W receives an appropriate amount of radially outward pressure evenly from a plurality (twelve, in the present embodiment) of the holding members 66, and the work W is held by the plurality of holding members 66 in an outwardly expanding (pushed from inside out) fashion. Above the base flange 56, a guiding plate 74 is provided to assist positioning of the work W when the work W is set onto the holding members 66. The guiding plate 74 is movable in an axial direction of the rotation shaft 46, and is moved back to a predetermined position by an unillustrated advancement/retraction drive motor when the setting of the work W onto the holding members 66 is completed.
In the present embodiment, as shown in
Next, description will be made for a method of setting the work holding section 65 (a plurality of the holding members 66) to the work W.
First, a set of four holding members 66 which are in a crisscross relationship in the twelve holding members 66 are set to an extending length which is shorter than the inner radius of the work W by approximately 0.5 mm. All of the other holding members 66 are set to a shorter extending length than these four. Next, one surface of the work W is pressed onto the guiding plate 74, to position the work W. Next, the four holding members 66 in the cross pattern are divided into two sets, with each set consisting of two holding members 66 which are in a rightly opposed relationship to each other. In each set, the two holding members 66 are alternately pushed radially outward. In this process, the adjustment screw 72 is turned with a torque wrench for example, whereby the holding member 66 is pushed. Then, once all of the four holding members 66 make contact with the inner circumferential surface of the work W, the holding members 66 are alternately torqued in each set, to a predetermined torque. Likewise, the remaining holding members 66 are divided into sets of two rightly opposed holding members 66, and in each set the holding members 66 are alternately torqued to the predetermined torque. Following the process described above, the inner circumferential surface of the work W is held by the work holding section 65 (a plurality of the holding members 66).
Next, a primary operation of the double disc surface grinding machine 10 will be described with reference to
First, the work W is held with the work holding section 65 as described above (Step S1). Next, the work table 38 is moved forward by the transport section 32, toward the bed column 12 to move the work W, which is held by the work holding section 65, to a grinding position. In other words, the work W is sent to between the pair of grinding wheels 16a, 16b (Step S3).
Next, the rotation-driving section 34 rotates the work W (Step S5). Specifically, a driving force from the drive motor 44 rotates the rotation shaft 46 integrally with the position adjustment section 76, the work holding section 65 and the work W, around the rotation shaft 46 in a direction indicated by an arrow R1 in
Next, the drive motors 24a, 24b rotate the grinding wheels 16a, 16b respectively, in a direction indicated by an arrow R2 in
Next, the grinding wheel feeding section 26b moves the right (see
Next, the left and right grinding wheels 16a, 16b are advanced to the positions of contact (Step S15), then a coarse grinding infeed is performed with the grinding wheels 16a, 16b (Step S17), and further, a fine grinding infeed is performed with the grinding wheels 16a, 16b (Step S19). Although the pair of grinding wheels 16a, 16b sandwich only part of the work W at any moment, the work W is rotating and therefore all parts of the surfaces of the work W which must be ground make passes between the pair of grinding wheels 16a, 16b, allowing both main surfaces of the work W to be ground simultaneously. Then, after a spark out (Step S21), the grinding wheels 16a, 16b are returned to their original positions (Step S23). Then, rotation of the work W is stopped (Step S25), and the work table 38 recedes from the bed column 12 to the location where the work W is removed/mounted (Step 27).
A cycle of Step S1 through Step S27 is repeated to sequentially grind a plurality of the works W.
Hereinafter, functions and advantages of the double disc surface grinding machine 10 will be explained.
According to the double disc surface grinding machine 10, the inner circumferential surface of the work W is held by the work holding section 65 so that the work W will not move with respect to the work holding section 65 (in other words, the work W will move integrally with the work holding section 65) during the grinding. Therefore, it is possible to decrease movement of the work W with respect to the work holding section 65 in the direction in which the pair of grinding wheels 16a, 16b are opposed to each other, during the grinding. The work holding section 65 does not hold two main surfaces (surfaces to be ground) of the work W. Therefore, even if the work W has warps in its surfaces to be ground, it is possible to decrease flailing movement of the work W during grinding. In other words, regardless of whether or not the work W has a warp, distortion, etc. in its surfaces to be ground, it is possible: to hold the inner circumferential surface of the work W with the work holding section 65 so that the rotation shaft 46, the position adjustment section 76, the work holding section 65 and the work W will rotate integrally with each other; to grind the work W based on the rotation shaft 46; and to reduce flailing movement of the work W during grinding.
It is possible to adjust the position of the work holding section 65 in the radial direction of the rotation shaft 46. This allows to move the work holding section 65 until it makes contact with the inner circumferential surface of the work W at a plurality of locations, regardless of the diameter or shape of the inner circumferential surface of the work W, and therefore to reliably hold the inner circumferential surface of the work W with the work holding section 65. It is possible to stably hold the work W of a various kinds. As a result, it is possible to use grinding wheels 16a, 16b of a small diameter when grinding the work W regardless of the diameter, warp, etc. of the work W; to ensure appropriate parallelism and flatness regarding the surfaces of the work W to be ground; to obtain good grinding accuracy; and to provide accuracy as reference surfaces used in a later process of machining on the inner and outer diameters.
A plurality of the holding members 66 which extend radially as viewed from the rotation shaft 46 hold the inner circumferential surface of the work W. Therefore, at each location of contact on the inner circumferential surface of the work W, only a small holding force (a pushing force exerted from the holding member 66 onto the inner circumferential surface of the work W) is sufficient. The holding members 66 may simply be advanced or retracted radially of the rotation shaft 46, to establish easily contact of the holding members 66 with the inner circumferential surface of the work W.
Position adjustment with respect to the inner circumferential surface of the work W can be made individually for each of the holding members 66. Therefore, it is possible to hold the inner circumferential surface of the work W suitably regardless of the kind of the work W. In other words, the inner circumferential surface of the work W need not necessarily be a true circle. It is possible to handle annular works having various shapes other than circler, such as oval, rectangular, hexagonal or rice-ball shaped. For example, it is possible to handle an oval-annular work W1 as shown in
Referring to
Since the rotation shaft 46 and the work W are concentric with each other, it is possible to perform position adjustment of the work holding section 65 with the position adjustment section 76 and holding on the inner circumferential surface of the work W more smoothly.
Since the work W can be ground from a state of material to a finished size within a single grinding cycle, productivity is improved, and since the grinding wheels 16a, 16b of a narrow effective grinding width can be used, it is possible to decrease cost on the grinding wheels. Further, it becomes possible to make the double disc surface grinding machine 10 compact.
In the embodiment described above, individual adjustment screws 72 are used to move corresponding ones of the holding members 66 radially outward to hold the inner circumferential surface of the work W. However, as in an embodiment shown in
Referring to
In the present embodiment, the work W is set, and then the cam shaft 78 is rotated leftward (counterclockwise (in an arrow R3 direction) in
According to this embodiment, the position adjustment section 76a is arranged to be capable of making a simultaneous position adjustment of a plurality of the holding members 66a. Therefore, the arrangement allows position adjustment of a plurality of the holding members 66a in a single operation. It is possible to perform a task of holding the inner circumferential surface of the work W with a plurality of the holding members 66a within a short time.
In the present embodiment, there is provided a plurality (twelve, in the present embodiment) of air cylinders 94 at a base flange 56b, together with a plurality (twelve, in the present embodiment) of holding members 66b which are included in the work holding section 65b. Each of the air cylinders 94 has a piston rod 96, to which a corresponding one of the holding members 66b is connected. Each air cylinder 94 is connected to an air supply joint 100 via a corresponding pipe 98. The air supply joint 100 is inserted through the center of the rotation shaft 46b coaxially therewith, and is rotatable integrally with the rotation shaft 46b. In other words, the rotation shaft 46b includes a cylindrical section 47b extending in the arrow H direction (see
According to this embodiment, it is possible to drive each of the holding members 66b individually with a single operation. With the use of air cylinders 94, it is possible to cause all of the holding members 66b to press and hold the inner circumferential surface of any work, which has a large inner diametrical difference (e.g., between the major and minor axes) or of a work of an irregular shape, with a uniform force regardless of the extended length (amount of stroke) of the individual holding members 66b. The air cylinders may be replaced with hydraulic cylinders. The same applies to embodiments shown in
In the embodiments described above, the holding members may be varied in their length and shape of tips, in accordance with the work to be machined. Then it becomes possible to handle works more flexibly, not only circularly annular works such as inner and outer rings of bearings, inner and outer rings of cross roller bearings, and piston rings but also works of any loop shapes such as triangular, rectangular, etc. For example, the length of each holding member 66b in the embodiment shown in
Referring to
The position adjustment section 76c includes a screw ring 49c, a base flange 56c and a holding plate 102.
The screw ring 49c is generally cylindrical, and is made the same as the screw ring 49 except that the screw ring 49c does not have the screw holes 54. In other words, the screw ring 49c is at a center region in the disc section 48 of the rotation shaft 46, and includes a cylindrical section 50c and a flange section 52 formed at an end region of the cylindrical section 50c. The screw ring 49c is attached to the base flange 56c.
The base flange 56c is made the same as the base flange 56 except that the base flange 56c does not have the guide grooves 60 and the protrusions 61. In other words, the base flange 56c is substantially hollow and disc-like, and has a circular hollow portion 58 into which the screw ring 49c is inserted. While the cylindrical section 50c of the screw ring 49c is fitted to the hollow portion 58, the flange section 52 of the screw ring 49c is attached to the base flange 56c with fasteners 62. Then, the base flange 56c, to which the screw ring 49c is attached, is fixed to an end portion (the disc section 48) of the rotation shaft 46 with a plurality (four, in the present embodiment) of fasteners 64. The holding plate 102 is attached to the base flange 56c.
The holding plate 102 is hollow and disc-like, has a circular hollow region 104 through which the screw ring 49c is inserted, and a plurality (twelve, in the present embodiment) of substantially rectangular through-holes 106. The plurality of through-holes 106 are formed substantially equidistantly in a circumferential direction of the holding plate 102. The holding plate 102 has a thickness which is slightly smaller than an axial thickness T of the work W so as to give the holding plate 102 increased bending rigidity without a risk that the holding plate 102 will be ground by the grinding wheels 16a, 16b. Also, the holding plate 102 has an outer diameter which is slightly smaller than an inner diameter of the work W. The outer diameter of the holding plate 102 is designed to make a gap G of, e.g., approximately 5 mm, between the holding plate 102 and the work W. The holding plate 102 is fixed to the base flange 56c with a plurality (six, in the present embodiment) of fixing bolts 108. Therefore, the rotation shaft 46, the screw ring 49c, the base flange 56c, and the holding plate 102 are coaxial with each other and simultaneously rotatable. In each of the through-holes 106 in the holding plate 102, there is formed a screw hole 110 extending radially (in radial directions) of the holding plate 102, penetrating to reach an outer circumferential surface of the holding plate 102. The screw holes 110 are provided to penetrate an appropriate thickness position (substantial center region of the thickness, in the present embodiment) of the holding plate 102.
The work holding section 65c includes a plurality (twelve, in the present embodiment) of bolt-like holding members 66c. Each of the holding members 66c is threaded into a corresponding one of the screw holes 110, radially (in a radial direction) of the holding plate 102. The plurality of the holding members 66c are disposed substantially equidistantly in a circumferential direction of the holding plate 102. By rotating the holding members 66c (in a clockwise or counterclockwise direction), it is possible to move closer to and away from the holding members 66c with respect to the inner circumferential surface of the work W, radially of the rotation shaft 46. In other words, it is possible to advance or retract the holding members 66c with respect to the screw holes 110 thereby adjusting the position of the holding members 66c by way of interaction between male threads in the holding members 66c and female threads in the screw holes 110. The holding members 66c are thus rotated in the circumferential direction to move outward until tip portions of the holding members 66c press onto the inner circumferential surface of the work W. By doing so, the inner circumferential surface of the work W receives an appropriate amount of radially outward pressure evenly from a plurality (twelve, in the present embodiment) of the holding members 66c, and the work W is held by the plurality of holding members 66c, in an outwardly expanding (pushed from inside out) fashion. The holding members 66c are fixed with locknuts 112. Other arrangements are the same as the embodiment in
According to this embodiment, the holding plate 102 which holds the holding members 66c is disc-like, and is formed as a single-piece without being divided in a circumferential direction. This allows the holding plate 102 to have a strong bending rigidity. Also, the embodiment allows the holding plate 102 to be increased in size until its outer diameter is close to the inner diameter of the work W. This allows the holding plate 102 to have a further increased bending rigidity. Further, a portion of each holding member 66c to be extended beyond the outer circumferential surface of the holding plate 102 is short, being equal to the dimension of the gap G. Thus, the holding members 66c resist bending forces and can become substantially integral with the holding plate 102. Therefore, each holding member 66c has substantially the same level of rigidity as the holding plate 102, i.e., it is possible to increase rigidity. This embodiment is advantageous particularly when the work W to be ground has a small thickness.
The work may be automatically clamped and held according to an embodiment shown in
Referring to
The position adjustment section 76d includes a base flange 56d, air cylinders 94, pipes 98, an air supply joint 100, a holding plate 102a, and an air supply source.
The base flange 56d is the same as the base flange 56b except that the base flange 56d does not have the guide grooves 60 and the protrusions 61. In other words, the base flange 56d is formed substantially hollow and disc-like. An inner diameter of the base flange 56d is substantially equal to an outer diameter of the air supply joint 100. The base flange 56d is fitted around the air supply joint 100, and is fixed to the hollow disc section 48b (see
The holding plate 102a is hollow and disc-like. In order to give a high level of bending rigidity to the holding plate 102a and in order to prevent the holding plate 102a from being ground by the grinding wheels 16a, 16b, the holding plate 102a has a slightly smaller thickness than an axial thickness T (see
The work holding section 65d includes a plurality (twelve, in the present embodiment) of rod-like holding members 66d. The plurality of holding members 66d are disposed substantially equidistantly in a circumferential direction of the holding plate 102a. Each of the holding members 66d is inserted through a corresponding one of the through-holes 110a to extend radially (in a radial direction) of the holding plate 102a and to move inward and outward smoothly with respect to the inner circumferential surface of the work W radially of the rotation shaft 46b. Each holding member 66d is connected to a piston rod 96 of a corresponding one of cylinders 94, via a connection joint 114. Thus, as an unillustrated air supply source supplies air through the air supply joint 100 and each of the pipes 98, to each of the air cylinders 94 which is disposed in the base flange 56d, all of the holding members 66d move outward to press an inner circumferential surface of the work W thereby holding the work W. After clamping the work W, the holding members 66d are fixed with locking screws 116 threaded into the holding plate 102a, integrally with the holding plate 102a (see
Further, the work may be automatically clamped and held according to an embodiment shown in
Referring to
The holding plate 102b is hollow and disc-like, and has a thick portion 118 in its outer circumferential region. Therefore, the holding plate 102b is formed to have an L-shaped section in its outer circumferential region. For increased bending rigidity of the holding plate 102b, the thick portion 118 of the holding plate 102b may be made greater than an axial thickness T of the work W. Also, the holding plate 102b has an outer diameter which is slightly smaller than an inner diameter of the work W. The holding plate 102b is fixed to an outer circumferential edge region of the base flange 56d with a plurality (six, in the present embodiment) of fixing bolts 108a. The thick portion 118 of the holding plate 102b has a plurality (twelve, in the present embodiment) of through-holes 110b. The plurality of through-holes 110b are formed substantially equidistantly in a circumferential direction of the holding plate 102b (thick portion 118), penetrating from an inner circumferential surface of the thick portion 118 to an outer circumferential surface thereof, radially (in radial directions).
The work holding section 65e includes a plurality (twelve, in the present embodiment) of rod-like holding members 66e. The plurality of holding members 66e are disposed substantially equidistantly in a circumferential direction of the holding plate 102b. Each of the holding members 66e is inserted through a corresponding one of the through-holes 110b to extend in a radial direction (radially) of the holding plate 102b and to move inward and outward smoothly with respect to the inner circumferential surface of the work W radially of the rotation shaft 46b. Each of the holding members 66e has a tip portion 120, which has a slightly smaller diameter than a width T of the work W so that the tip portion 120 can be brought between the grinding wheels 16a, 16b without making contact with the grinding wheels 16a, 16b while holding the work W. By positioning an outer circumferential surface of the holding plate 102b closely to the grinding wheels 16a, 16b, it becomes possible to shorten a length of the tip portion 120. Part of the holding member 66e other than the tip portion 120 is outside of the grinding wheels 16a, 16b and therefore can be made thicker to give increased rigidity to the holding members 66e. Each holding member 66e is connected to a piston rod 96 of a corresponding one of cylinders 94, via a connection joint 114. After clamping the work W, the holding members 66e are fixed with locking screws 116a threaded into the holding plate 102b, and becomes integral with the holding plate 102b. Therefore, each holding member 66e has substantially the same level of rigidity as the disc-like holding plate 102b, i.e., it is possible to increase rigidity. Other arrangements are the same as the embodiment in
According to this embodiment, there is no need for inserting the holding plate 102b between the grinding wheels 16a, 16b, so it is possible to increase the thickness of the holding plate 102b without being limited by the thickness of the work W, and therefore to further increase the rigidity of the holding plate 102b. Also, by shortening the length of the tip portion 120 in the holding member 66e, it becomes possible to further increase rigidity which is given by an integral structure of the holding plate 102b and the holding members 66e. Especially, this can be achieved more effectively by increasing a distance between the center C1 of the rotation shaft 46b which rotates the work W and the center of the grinding wheels 16a, 16b and decreasing a distance L (see
The present invention is not limited to cases where both in the pair of grinding wheels are advanced to the work, but is also applicable to cases where only one in the pair of grinding wheels is advanced to the work when the work is sandwiched by the pair of grinding wheels for grinding both main surfaces of the work.
In the embodiments described above, the present invention was applied to horizontal double disc surface grinding machines. However, the present invention is also applicable to vertical double disc surface grinding machines in which grinding wheel shaft is made vertical.
Also, the present invention is applicable not only to infeed grinding but also to so called creep feed grinding in which a rotating work is fed from outside of the grinding wheels toward the grinding wheels, and also to traverse creep feed grinding in which creep grinding is repeated.
The present invention being thus far described in terms of preferred embodiments, it is obvious that these may be varied in many ways within the scope and the spirit of the present invention. The scope of the present invention is only limited by the accompanied claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-007031 | Jan 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/051153 | 1/16/2015 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2015/108174 | 7/23/2015 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 1627858 | Morgal | May 1927 | A |
| 1956700 | Shelly | May 1934 | A |
| Number | Date | Country |
|---|---|---|
| 09-010265 | Jul 1934 | JP |
| H09-10265 | Jul 1934 | JP |
| S45-5359 | Mar 1970 | JP |
| SHOU 58-102606 | Jun 1983 | JP |
| H11-239894 | Sep 1999 | JP |
| 2002-96202 | Apr 2002 | JP |
| 2002-96262 | Apr 2002 | JP |
| 2004-42129 | Feb 2004 | JP |
| 2007-229830 | Sep 2007 | JP |
| 2008-149409 | Jul 2008 | JP |
| 2007099653 | Sep 2007 | WO |
| Entry |
|---|
| The International Preliminary Report on Patentability dated Jul. 28, 2016 for International Application No. PCT/JP2015/051153. |
| International Search Report for International Application No. PCT/JP2015/051153 dated Mar. 3, 2015. |
| Office Action dated Jan. 12, 2016 for corresponding Japanese Patent Application No. 2015-007269, with English translation. |
| Extended European Search Report for counterpart EPC Patent Application No. 15737940.5 dated Aug. 17, 2017 (7 Sheets). |
| Number | Date | Country | |
|---|---|---|---|
| 20160207159 A1 | Jul 2016 | US |
