JP2015147277A - Flat grinding device and flat grinding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat grinding device capable of positioning at high accuracy.SOLUTION: A flat grinding device has a table 10 holding a material to be ground and movable to a first direction by a main drive unit 20 with respect to a base frame 12, and at least one grinding wheel. A support mechanism 40 capable of selecting either one of the restraint and releasing states supports a sub-drive unit 30 including an electric servomotor 31 and installed to the table 10 to the base frame 12. When the support mechanism 40 is in a restraint state, the sub-drive unit 30 can move the table 10 to the first direction by operating the electric servomotor 31, and when the mechanism 40 is in a releasing state, the sub-drive unit 30 moves to the first direction together with the table 10. The positioning accuracy of the table 10 by the sub-drive unit 30 is higher than that by the main drive unit 20 and besides, the movable range of the table 10 by the main drive unit 20 is wider than that by the sub-drive unit 30.

Description

  The present invention relates to a surface grinding apparatus and a surface grinding method.

  Conventionally, the table of the surface grinding apparatus is hydraulically driven (Patent Document 1). When grinding the upper surface of the workpiece while moving the table at a constant speed, there is no problem by using a hydraulically driven table. In recent years, in order to improve the machining efficiency, there is an increasing demand for five-side machining that also processes the front and rear end faces while holding the workpiece on a table for processing the upper surface of the workpiece.

  When grinding the upper surface of the workpiece, it is sufficient to move the table at a constant speed, and absolute positional accuracy of the table is not required. However, when processing the end face of an object to be ground, high positioning accuracy is required for the table.

  Patent Document 2 discloses a high-speed feeding device that combines a ball screw and a hydraulic cylinder to move a table at high speed. In this high-speed feeding device, a large driving force and a braking force are applied to the table from the hydraulic cylinder when the table is started and stopped. As a result, the table is started and stopped smoothly and accurately.

  Patent Document 3 discloses an apparatus for positioning a table with high accuracy using a coarse movement mechanism and a voice coil motor. In this device, a table is attached to the carriage via a voice coil motor. The coarse movement mechanism moves the carriage in the axial direction, so that the carriage and the table are roughly positioned. After the rough positioning, the position of the table can be finely adjusted with respect to the carriage by driving the voice coil motor.

JP 2013-226634 A JP-A-3-256638 JP 2002-355730 A

  A table used in a surface grinding apparatus has a large inertia because the weight may reach several tens of tons. When this table is driven by a hydraulic cylinder, the volume of hydraulic oil increases, and the frequency response characteristic of the hydraulic cylinder system is reduced to about several Hz. It is not uncommon for the sliding resistance of the table to exceed 1 ton. Due to these characteristics, a so-called stick-slip phenomenon occurs in the slow speed region, and it is difficult to perform highly accurate positioning.

  In a high-speed feed device that combines a ball screw and a hydraulic cylinder, the stroke of the ball screw is substantially equal to the stroke of the hydraulic cylinder. In order to ensure a large stroke, both the ball screw and the hydraulic cylinder must be enlarged.

In the apparatus using the coarse movement mechanism and the voice coil motor, the coarse movement mechanism, the voice coil, and the table are connected in series, so that the driving force during the coarse movement is directly applied to the voice coil. For this reason, a voice coil having a driving force equivalent to that of the coarse movement mechanism is required. In particular, when the weight of the table is large as in the surface grinding apparatus, the voice coil becomes huge. For this reason, it is difficult to apply the apparatus using the coarse movement mechanism and the voice coil motor to the surface grinding apparatus.

  An object of the present invention is to provide a surface grinding apparatus and a surface grinding method capable of performing highly accurate positioning.

According to one aspect of the invention,
A table configured to hold an object to be ground and supported to be movable in a first direction with respect to the base frame;
At least one grinding wheel for grinding an object to be ground held on the table;
A main drive for moving the table in the first direction;
A sub-drive device;
The sub drive device is supported with respect to the base frame, and a release state in which the sub drive device is movable in the first direction and a restraint state in which a position with respect to the base frame is restrained can be selected. And a support mechanism,
When the support mechanism is in the restrained state, the sub drive device can move the table in the first direction, and when the support mechanism is in the released state, the sub drive device is moved together with the table to the first position. The positioning accuracy of the table by the sub driving device is higher than the positioning accuracy of the table by the main driving device, and the movable range of the table by the main driving device is A surface grinding apparatus wider than the movable range of the table by the driving device is provided.

According to another aspect of the invention,
Grinding the upper surface of the workpiece while moving the table holding the workpiece in the first direction by operating the main drive unit;
Operating the main driving device to move the table together with the sub driving device in the first direction to perform rough positioning of the table in the first direction;
After the rough positioning of the table, the main driving device is brought into a neutral state in which the table is free to move in the first direction, and the sub driving device is operated to operate the first direction of the table. Fine-tuning the position with respect to,
After fine adjustment of the position of the table, there is provided a surface grinding method including a step of grinding the surface of the workpiece to be orthogonal to the first direction.

  The upper surface of the workpiece can be ground while moving the table with the main drive unit. By finely adjusting the position of the table with the auxiliary driving device, the positioning accuracy of the table can be increased.

FIG. 1 is a schematic perspective view of a surface grinding apparatus according to an embodiment. FIG. 2 is a schematic plan view of the surface grinding apparatus according to the embodiment. 3 is a cross-sectional view taken along one-dot chain line 3-3 in FIG. FIG. 4 is a cross-sectional view of the surface grinding device when the support mechanism of the sub-drive device mounted on the surface grinding device according to the embodiment is released. FIG. 5 is a cross-sectional view of the surface grinding device when the support mechanism of the auxiliary drive device mounted on the surface grinding device according to the embodiment is in a restrained state. 6 is a cross-sectional view taken along one-dot chain line 6-6 in FIG. 2 when the support mechanism is in the released state. 7 is a cross-sectional view taken along one-dot chain line 6-6 in FIG. 2 when the support mechanism is in a restrained state. FIG. 8 is a flowchart of the surface grinding method according to the embodiment. FIG. 9 is a schematic plan view of a surface grinding apparatus according to a modification of the embodiment.

  In FIG. 1, the schematic perspective view of the surface grinding apparatus by an Example is shown. An xyz orthogonal coordinate system is defined in which the horizontal plane is the xy plane and the vertical downward direction is the positive direction of the z axis. A table 10 is supported by a linear motion guide 11 so as to be movable in the x direction. A workpiece 15 is held on the table 10. A first grindstone head 16 is supported above the table 10 so as to be movable in the y direction. The first grinding wheel head 16 includes a first grinding wheel 17 having a rotation center parallel to the y axis. The top surface of the workpiece 15 is ground by the first grinding wheel 17 while moving the workpiece 15 in the x direction at a constant speed.

  A second grindstone head 18 is supported on the side of the table 10 so as to be movable in the y direction. The second grinding wheel head 18 includes a second grinding wheel 19 having a center of rotation parallel to the z-axis. The surface (end face) perpendicular to the y direction of the workpiece 15 is ground by the second grinding wheel 19 by moving the workpiece 15 in the x direction by stopping the second grinding wheel head 18. be able to. The surface (end face) perpendicular to the x direction of the workpiece 15 can be ground by moving the workpiece 15 stationary and moving the second grindstone head 18 in the y direction. In addition, you may use the universal grindstone which can grind an upper surface and an end surface with one grindstone.

  The control device 13 controls the movement of the table 10, the first grindstone head 16, and the second grindstone head 18.

  FIG. 2 is a plan view of the surface grinding apparatus according to the embodiment. The linear motion guide 11 is supported by the base frame 12. The table 10 is supported by the linear motion guide 11 so as to be movable in the x direction. The main drive device 20 moves the table 10 in the x direction. For example, a hydraulic cylinder mechanism is used for the main drive device 20.

  The main drive device 20 includes a cylinder 21, a piston 22, a first piston rod 23F, and a second piston rod 23B. The cylinder 21 is fixed to the bottom surface of the table 10. A piston 22 is inserted into the cylinder 21, and the space in the cylinder 21 is divided into a first pressure chamber 24F and a second pressure chamber 24B by the piston 22.

  The first piston rod 23F extends from the piston 22 in the positive x-axis direction, and the second piston rod 23B extends in the negative x-axis direction. The first piston rod 23F, the second piston rod 23B, and the piston 22 are fixed to the base frame 12. Through the hydraulic oil path provided in the first piston rod 23F, the hydraulic oil is introduced into and discharged from the first pressure chamber 24F. The hydraulic oil is introduced into and discharged from the second pressure chamber 24B through the hydraulic oil path provided in the second piston rod 23B.

  A sub-drive device 30 is attached to the table 10. The sub drive device 30 includes an electric servo motor 31 and a ball screw 32. The rotation axis of the ball screw 32 is parallel to the x direction. The electric servo motor 31 rotates the screw shaft 32 </ b> A of the ball screw 32. As the electric servo motor 31, for example, an induction motor, a synchronous motor, a stepping motor or the like is used. A nut 32 </ b> B of the ball screw 32 is fixed to the table 10.

The support mechanism 40 supports the auxiliary drive device 30 so as to be movable in the x direction. The support mechanism 40 includes a linear motion guide 41 attached to the base frame 12 and a support plate 42 guided by the linear motion guide 41 in the x direction. The electric servo motor 31 is fixed to the support plate 42. When the electric servomotor 31 is operated, the distance between the support plate 42 and the table 10 in the x direction varies.

  A linear scale 50 is attached to the side surface of the table 10 parallel to the x direction. When the sensor 51 reads the linear scale 50, the position of the table 10 in the x direction can be detected. The reading result of the sensor 51 is input to the control device 13. The main drive device 20 and the sub drive device 30 are controlled by the control device 13.

  FIG. 3 is a schematic cross-sectional view taken along one-dot chain line 3-3 in FIG. A cylinder 21 having a central axis parallel to the x direction is fixed to the bottom surface of the table 10. A piston 22 is inserted into the cylinder 21. The piston 22 divides the space in the cylinder 21 into a first pressure chamber 24F on the positive side of the x axis and a second pressure chamber 24B on the negative side of the x axis. The first piston rod 23F and the second piston rod 23B extend from the piston 22 in the positive and negative directions of the x-axis, respectively. The first piston rod 23F and the second piston rod 23B are fixed to the base frame 12.

  A first hydraulic oil path 25F is provided in the first piston rod 23F, and a second hydraulic oil path 25B is provided in the second piston rod 23B. The first hydraulic oil path 25F and the second hydraulic oil path 25B are continuous with the first pressure chamber 24F and the second pressure chamber 24B, respectively. The first hydraulic oil path 25F and the second hydraulic oil path 25B are connected to the first discharge port 26F and the second discharge port 26B of the bidirectional hydraulic pump 26, respectively. The bidirectional hydraulic pump 26 is driven by a hydraulic pump drive motor 27. The hydraulic pump drive motor 27 is controlled by the control device 13.

  By driving the bidirectional hydraulic pump 26, the table 10 can be moved in the positive or negative direction of the x-axis. Instead of the bidirectional hydraulic pump 26, a hydraulic pump having one discharge port and a direction control valve for switching the direction of the flow of hydraulic oil may be used.

  The support mechanism 40 includes a linear motion guide 41 and a support plate 42. A support plate 42 is supported by the linear motion guide 41 so as to be movable in the x direction. The support mechanism 40 can selectively realize a released state in which the support plate 42 can move in the x direction and a restrained state in which the position of the support plate 42 is restrained. When the support mechanism 40 is in a restrained state, the position of the support plate 42 is restrained with respect to the base frame 12.

  The electric servo motor 31 is fixed to the support plate 42. A screw shaft 32 </ b> A of the ball screw 32 is coupled to a rotating shaft of the electric servo motor 31, and a nut 32 </ b> B is fixed to the table 10.

  FIG. 4 shows a cross-sectional view of the flat plate grinding apparatus when the support mechanism 40 is in the released state. The sub drive device 30 can move freely in the x direction. When the bidirectional hydraulic pump 26 is operated to move the table 10 in the x direction, the auxiliary driving device 30 also moves in the x direction together with the table 10.

  FIG. 5 shows a cross-sectional view of the flat plate grinding apparatus when the support mechanism 40 is in a restrained state. The bidirectional hydraulic pump 26 is in a neutral state in which hydraulic oil can freely flow between the first discharge port 26F and the second discharge port 26B. At this time, the table 10 is freely movable in the x direction without being restrained by the main drive device 20.

Since the support plate 42 and the electric servo motor 31 are fixed to the base frame 12, when the electric servo motor 31 is operated, the rotary motion is converted into a linear motion by the ball screw 32, and the table 10 moves in the x direction. To do.

  FIG. 6 is a cross-sectional view taken along one-dot chain line 6-6 in FIG. A table 10 is supported by a linear motion guide 11 so as to be movable in the x direction. The rail 11A of the linear guide 11 is fixed to the base frame 12 (FIG. 2). The movable portion 11 </ b> B of the linear motion guide 11 is fixed to the table 10. The support plate 42 is supported by the linear motion guide 41 so as to be movable in the x direction. The rail 41A of the linear guide 41 is fixed to the rail 11A of the linear guide 11. The movable portion 41 </ b> B of the linear guide 41 is fixed to the support plate 42.

  A clamp mechanism 43 and an electric servo motor 31 are attached to the support plate 42. The clamp mechanism 43 includes a clamp cylinder 43A, a clamp piston 43B, and a clamp portion 43C. The clamp cylinder 43A is fixed to the support plate 42, and the clamp piston 43B moves up and down in the clamp cylinder 43A. A clamp portion 43C is attached to the lower end of the clamp piston 43B.

  The linear motion guide 41, the support plate 42, and the clamp mechanism 43 constitute the support mechanism 40. FIG. 6 shows a cross-sectional view when the support mechanism 40 is in the released state. When the support mechanism 40 is in the released state, the clamp piston 43B is lowered to the lower end, and the clamp portion 43C is not in contact with the rail 41A of the linear motion guide 41. For this reason, the support plate 42 can freely move in the x direction.

  FIG. 7 is a cross-sectional view taken along one-dot chain line 6-6 in FIG. 2 when the support mechanism 40 is in a restrained state. The clamp piston 43B moves upward, and the clamp portion 43C is in contact with the rail 41A of the linear guide 41. The position of the support plate 42 is restrained by the frictional force between the clamp portion 43C and the rail 41A. The clamp mechanism 43 is controlled by the control device 13 (FIG. 2).

  FIG. 8 shows a flowchart of the surface grinding method according to the embodiment. With the workpiece 15 held on the table 10 (FIG. 1), the support mechanism 40 (FIGS. 4 and 6) is released in step S1. In step S2, as shown in FIG. 4, the main driving device 20 is operated to move the table 10 in the x direction at a constant speed, while the upper surface of the workpiece 15 is moved to the first grinding wheel 17 (FIG. 1). Grind with. By alternately repeating the movement of the table 10 in the x direction and the movement of the first grindstone head 16 in the y direction, the entire upper surface of the workpiece 15 is ground.

  In step S <b> 3, the table 10 is moved to a position where the side surface of the workpiece 15 can be ground by the second grinding wheel 19 by operating the main drive device 20 (FIG. 2). In this step S3, the rough positioning of the table 10 is completed. At this time, since the support mechanism 40 (FIG. 4) is in the released state, the sub drive device 30 moves in the x direction together with the table 10.

  In step S4, as shown in FIG. 5, the support mechanism 40 is brought into a restrained state, and the main drive device 20 is brought into a neutral state. In step S5, the position of the table 10 is finely adjusted in the x direction by operating the auxiliary drive device 30. After fine adjustment, the electric servo motor 31 is servo-locked. In step S6, the surface (end face) perpendicular to the x direction of the workpiece 15 is ground by moving the second grindstone head 18 (FIG. 1) in the y direction while the table 10 is stationary. .

  In FIG. 8, the end surface is ground after the top surface is ground, but the top surface may be ground after the end surface is ground.

  Next, effects of the surface grinding apparatus and the surface grinding method according to the above embodiment will be described. The weight of the table 10 (FIG. 1) used in the above embodiment generally reaches several tens of tons. Moreover, in order to grind the big to-be-ground material 15 (FIG. 1), it is necessary to ensure a long stroke. For this reason, the total volume of the first pressure chamber 24F (FIG. 3) and the second pressure chamber 24B (FIG. 3) in the cylinder 21 used in the main drive device 20 is increased. Furthermore, it is not uncommon for the sliding resistance of the table 10 to exceed 1 ton. By increasing the volume of the hydraulic oil in the cylinder 21 and the sliding resistance, a stick-slip phenomenon is likely to occur in the very low speed region. When the stick-slip phenomenon occurs, it is difficult to position the table 10 with high accuracy.

  In the embodiment, in step S5 (FIG. 8), the position of the table 10 is finely adjusted by the auxiliary driving device 30. The auxiliary drive device 30 using the electric servo motor 31 and the ball screw 32 has higher response characteristics than the main drive device 20 using a hydraulic cylinder. For this reason, it is possible to perform highly accurate positioning control even in the negative resistance region where the friction is changed from static friction to dynamic friction when positioning the table 10. As described above, the positioning accuracy of the table 10 by the auxiliary driving device 30 is higher than the positioning accuracy of the table 10 by the main driving device 20. Thereby, the grinding precision at the time of grinding of the side surface of the workpiece 15 in step S6 (FIG. 8) can be improved.

  Furthermore, in the embodiment, when the upper surface of the workpiece 15 is ground while moving the table 10 at a constant speed (step S2), and when the table 10 is roughly positioned (step S3), it is shown in FIG. Thus, the main drive device 20 directly drives the table 10 without the intermediary drive device 30 interposed. For this reason, the driving force equivalent to that at the time of main driving is not required for the auxiliary driving device 30. As a driving force required for the sub-driving device, a low driving force necessary for precise positioning is sufficient. In addition, since the speed at the time of positioning is preferably a low speed, it is possible to use a secondary drive device having a rated output much smaller than that of the main drive device. In the configuration in which the main drive device and the sub drive device are connected in series, a sub drive device having a rated output comparable to that of the main drive device must be used. On the other hand, in the apparatus according to the embodiment, the auxiliary drive apparatus having a smaller rated output than the main drive apparatus can be used, so that the cost of the apparatus can be reduced.

  The sub-drive device 30 is used for fine adjustment of the position of the table 10 and is not used for constant speed movement of the table 10 when grinding the upper surface of the workpiece 15. For this reason, a linear motion drive device having a smaller movable range (stroke) than the main drive device 20 can be used as the auxiliary drive device 30. In the above embodiment, the electric servo motor 31 and the ball screw 32 are used for the auxiliary drive device 30, but other linear motion drive devices with higher positioning accuracy than the main drive device 20 may be used. For example, a hydraulic drive device in which the volume of the pressure chamber in the cylinder is smaller than the volume of the pressure chamber in the cylinder 21 (FIG. 3) of the main drive device 20 can be used as the auxiliary drive device 30. By reducing the volume of the pressure chamber, high response characteristics with respect to pressure can be obtained, and high positioning accuracy can be realized.

  In FIG. 9, the top view of the surface grinding apparatus by the modification of an Example is shown. In the embodiment shown in FIGS. 1 to 8, the ball screw 32 of the sub drive device 30 is always coupled to the table 10. In the modification shown in FIG. 9, the nut 32 </ b> B of the ball screw 32 is detachably attached to the table 10. For this reason, it is possible to separate the sub drive device 30 from the table 10. As described above, the connected state in which the auxiliary driving device 30 is connected to the table 10 and moves together with the table 10 and the separation that is disconnected from the table 10 and can move the table 10 while the auxiliary driving device 30 is stationary. State is feasible. FIG. 9 shows a state where the sub drive device 30 is separated from the table 10.

  In this modification, when the upper surface of the workpiece 15 is ground (step S <b> 2), the auxiliary driving device 30 is separated from the table 10. Prior to rough positioning of the table 10 (step S3), the sub-drive device 30 is coupled to the table 10. In this state, by performing steps S3 to S6 in FIG. 8, the side surface of the workpiece 15 can be ground.

  During grinding of the upper surface of the workpiece 15, the load applied to the main drive device 20 can be reduced because the sub drive device 30 is disconnected from the table 10 during the period in which the table 10 is moved at a constant speed.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 Table 11 Linear motion guide 11A Rail 11B Movable part 12 Base frame 13 Control apparatus 15 To-be-ground object 16 1st grinding wheel head 17 1st grinding wheel 18 2nd grinding wheel 19 2nd grinding wheel 20 Main drive device 21 Cylinder 22 Piston 23F 1st piston rod 23B 2nd piston rod 24F 1st pressure chamber 24B 2nd pressure chamber 25F 1st hydraulic fluid path 25B 2nd hydraulic fluid path 26 Bidirectional hydraulic pump 26F 1st discharge port 26B 2nd discharge port 27 Hydraulic pump drive motor 30 Sub drive device 31 Electric servo motor 32 Ball screw 32A Screw shaft 32B Nut 40 Support mechanism 41 Linear motion guide 41A Rail 41B Movable part 42 Support plate 43 Clamp mechanism 43A Clamp cylinder 43B Clamp piston 43C Clamp part 50 Linear Scale 51 sensor

Claims (6)

A table configured to hold an object to be ground and supported to be movable in a first direction with respect to the base frame;
At least one grinding wheel for grinding an object to be ground held on the table;
A main drive for moving the table in the first direction;
A sub-drive device;
The sub drive device is supported with respect to the base frame, and a release state in which the sub drive device is movable in the first direction and a restraint state in which a position with respect to the base frame is restrained can be selected. And a support mechanism,
When the support mechanism is in the restrained state, the sub drive device can move the table in the first direction, and when the support mechanism is in the released state, the sub drive device is moved together with the table to the first position. The positioning accuracy of the table by the sub driving device is higher than the positioning accuracy of the table by the main driving device, and the movable range of the table by the main driving device is A surface grinding device wider than the movable range of the table by the driving device.   The surface grinding apparatus according to claim 1, wherein at least one of the grinding wheels is configured to grind a surface orthogonal to the first direction of an object to be ground held on the table.   The surface grinding device according to claim 1, wherein the auxiliary driving device includes an electric servo motor and a ball screw.   A connected state in which the secondary driving device is connected to the table and moves together with the table and a disconnected state in which the secondary driving device is detached from the table and can move the table while the secondary driving device is stationary are realized. The surface grinding apparatus according to claim 1, which is possible. Grinding the upper surface of the workpiece while moving the table holding the workpiece in the first direction by operating the main drive unit;
Operating the main driving device to move the table together with the sub driving device in the first direction to perform rough positioning of the table in the first direction;
After the rough positioning of the table, the main driving device is brought into a neutral state in which the table is free to move in the first direction, and the sub driving device is operated to operate the first direction of the table. Fine-tuning the position with respect to,
And a step of grinding the surface of the workpiece to be perpendicular to the first direction after fine adjustment of the position of the table.   6. The surface grinding method according to claim 5, wherein, in the step of grinding the upper surface of the workpiece, the auxiliary driving device is also moved in the first direction together with the table.

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