JP4398537B2 - Work support device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a workpiece support device suitable for use in a workpiece mounting jig for fixing a workpiece to be machined with a machine tool.
[0002]
[Prior art]
Conventionally, when machining such as plane machining, drilling, and boring with a machine tool, the workpiece is generally fixed by attaching the workpiece to a workpiece mounting jig fixed on the table of the machine tool. Thus, machining is performed on the fixed workpiece. An example of this workpiece mounting jig is shown in FIG . FIG. 3 shows an example of mounting a workpiece W having a structure in which a boss portion Wb having a through hole Wa formed at the center and a flange portion Wc formed around the boss portion Wb. .
[0003]
As shown in the figure, the workpiece mounting jig 101 includes a base 102, a positioning member 103, a support member 104 and a hydraulic clamper 105 provided on the base 102, and an operation boosted to a predetermined pressure. It comprises a hydraulic pressure supply unit (not shown) that supplies oil to the hydraulic clamper 105 as appropriate. The positioning member 103 includes a base portion 103b and a projection portion 103a that is erected on the base portion 103b and is fitted into the through hole Wa of the workpiece W. The workpiece W has a through hole Wa that is a projection portion. It is placed on the base 103b in a state of being fitted to 103a and positioned on the base 102.
[0004]
A plurality of the support members 104 are disposed on the base 102, and the upper end surfaces of the support members 104 are in contact with and support the lower surface of the flange portion Wc of the workpiece W, respectively. The hydraulic clamper 105 is connected to a hydraulic cylinder 106 that is operated by supplying hydraulic oil from a hydraulic supply unit (not shown), and a piston rod of the hydraulic cylinder 106, and is operated in the vertical direction by the operation of the hydraulic cylinder 106. It consists of a moving clamp member 107. The clamp member 107 is moved downward by the operation of the hydraulic cylinder 106, whereby the flange portion Wc of the workpiece W supported by the support member 104 is sandwiched from above and below by the clamp member 107 and the support member 104. As a result, the workpiece W is fixed.
[0005]
In this case, the step dimension (the difference between the upper surface height dimension of the support member 104 and the upper surface height dimension of the base portion 103b) Lj between each of the support members 104 and the base portion 103b of the positioning member 103 is equal to the workpiece W. Step dimensions (dimensions from the bottom surface of the boss portion Wb to the bottom surface of the flange portion Wc) Lw are accurately manufactured, and when the workpiece W is placed on the base portion 103b of the positioning member 103, The upper surfaces of the support members 104 are in contact with the lower surface (supported surface) of the flange Wc of the workpiece W having the reference step dimension Lw.
[0006]
[Problems to be solved by the invention]
However, the step dimension Lw of the workpiece W described above is normally allowed to have a certain variation in machining accuracy, and when the workpiece W having such a variation is attached to the workpiece attachment jig 101, the step dimension Lw. Is larger than the reference dimension, the flange portion Wc of the workpiece W is pushed down to a position where it abuts against the upper surface of the support member 104 by the hydraulic clamper 105, and the workpiece W is elastically deformed, while the step dimension Lw is smaller than the reference dimension. In some cases, the boss Wb of the workpiece W is not placed on the base 103b of the positioning member 103 and is in a floating state, and the workpiece W undergoes elastic deformation or chatter vibration due to a machining load during machining. Further, in the workpiece mounting jig 101 of this example, the upper surface of the boss Wb of the workpiece W is pressed downward by the hydraulic clamper 105 or the like so that the boss Wb is sandwiched between the base 103b. However, in this case, if the step dimension Lw is smaller than the reference dimension as described above, the lower surface of the boss Wb is pushed down to a position where it abuts on the upper surface of the base 103b.
[0007]
In this way, there is a variation in the step size Lw, and when the workpieces W having different elastic deformation amounts (clamp strain) at the time of clamping are machined, the machining dimensions vary by the difference in the elastic deformation amount between the workpieces W. become. Therefore, in the conventional workpiece mounting jig 101, when high-precision machining such as the order of 10 ⁻³ mm or the order of 10 ⁻⁴ mm is required, such a high-precision machining cannot be guaranteed. was there. Further, even when chatter vibration is generated in the workpiece W due to the processing load as described above, high-accuracy processing cannot be similarly guaranteed.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a workpiece support device capable of realizing high-precision machining by pressing a workpiece clamp distortion within an allowable range.
[0009]
[Means for solving the problems and effects thereof]
This onset Ming To achieve the above object, provided in the mounting jig, a support apparatus for supporting a work attached to the mounting jig, a support member for supporting the workpiece in contact with the workpiece A driving means for moving the support member forward and backward in a direction perpendicular to the support surface of the support member for supporting the workpiece by a driving force of the servo motor, and a mounting position of the mounting jig. A position detection means for detecting a position of a supported surface of the transferred work supported by the support member; and driving and controlling the servomotor based on position data detected by the position detection means, and a position control means for the support surface position of the support member moves the support member to coincide with the supported surface position of the workpiece, the position control means, the support surface position of the support member The servomotor is feedback-controlled so that it is positioned at a target position that matches the position of the supported surface of the workpiece, and it is determined that an excessive machining load has occurred when the control current related to the feedback control exceeds the allowable range. It is comprised so that it may carry out.
[0010]
According to the present invention, the position of the supported surface of the workpiece transferred to the mounting position on the mounting jig is detected by the position detection means, and the detected position data is transmitted from the position detection means to the position control means. Then, the position control means drives the servo motor based on the received position data, and moves the support member so that the support surface position of the support member coincides with the supported surface position of the workpiece. Thereby, the support surface of the said support member contact | abuts to the to-be-supported surface of the said workpiece | work, and a workpiece | work is supported by this support member.
[0011]
Thus, according to the present invention, by moving the support member so that the support surface position of the support member coincides with the supported surface position of the workpiece, the support surface comes into contact with the supported surface of the workpiece. Since there are variations in the dimensions of the workpiece, even when the supported surface position varies depending on the individual workpiece when transferred to the mounting position, the support surface of the support member is The workpiece can be reliably brought into contact with the supported surface. Therefore, it is possible to minimize the clamping distortion that occurs when the workpiece is clamped appropriately by the clamping means. By making the clamp distortion as small as possible in this way, it is possible to reduce the processing error associated with the clamp distortion and to realize high-precision processing such as the order of 10 ⁻³ mm or 10 ⁻⁴ mm. it can.
[0012]
In addition, the said servo motor is feedback-controlled so as to be positioned to the target position the support surface position of the supporting support member coincides with the supported surface position of the workpiece, the support surface position of the workpiece support surface position of the support member The clamp distortion can be made small, and the clamp distortion for each workpiece can be made uniform. As a result, the processing error associated with the clamp distortion can be further reduced, and highly accurate processing can be realized.
[0013]
By the way, when a machining load acts on the workpiece and a force that can be moved by the machining load acts on the support member, the position control means responds so that the support surface of the support member stops at the target position. The servo motor is feedback controlled by increasing the control current. Therefore, by monitoring this control current, the force acting on the support member, that is, the machining load can be detected. In the present invention , the position control means is configured to determine that an excessive machining load has occurred when a control current for feedback control of the servo motor exceeds an allowable range. It can be detected Do processing load, if an excessive load is detected, or decelerating the feed speed and the rotational speed of the tool, or a measure such changes the tools can and Turkey. As a result, the workpiece may be displaced due to an excessive machining load, resulting in a defective product, or the workpiece may be detached from the mounting jig, which may damage the tool, the mounting jig, or the machine tool. This can be prevented, and stable processing can be realized.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view showing a workpiece attachment jig according to the present embodiment, and FIG. 2 is a cross-sectional view in the direction of arrows AA in FIG. As shown in FIG. 1, the workpiece mounting jig 1 of this example is provided with a supporting device 10 instead of the supporting member 104 of the conventional workpiece mounting jig 101 shown in FIG. The configuration is the same as that of the conventional workpiece mounting jig 101. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.
[0015]
As shown in FIG. 2, the support device 10 is provided in the housing 11, a housing 11 fixed on the base 102, a support member 21 that contacts and supports the lower surface of the work W. A drive transmission unit including a gear 15, a gear 16, a drive shaft 19, and a push-up member 20 that moves the support member 21 in the vertical direction; a cover member 24 that houses the push-up member 20; The operation of the servo motor 13 is controlled based on the position data detected by the position detection sensor 23, the sensor holding member 22, the servo motor 13 that transmits power to the drive shaft 19, and the position data detected by the position detection sensor 23. And a control device 30.
[0016]
The housing 11 is made of a block-shaped member having a hollow portion, and openings are formed above and below the hollow portion. In addition, the drive shaft 19 and the gear 16 that is externally fitted to the hollow shaft, and the gear 15 are arranged so as to mesh with the gear 16.
[0017]
The drive shaft 19 is made of a cylindrical member, and is rotatably supported by bearing metals 17 and 18 each having an L-shaped longitudinal section provided in each of the openings. The gear 16 is locked to the drive shaft 19 by a key 19a, and rotates around the shaft together with the drive shaft 19. The drive shaft 19 is provided so that a part thereof protrudes from the upper opening of the housing 11, and the upper opening is sealed with a nut 12. Further, when the nut 12 is tightened, the gear 16 is sandwiched from above and below by the bearing metals 17 and 18 so that the vertical movement is braked. Inside the drive shaft 19, the sensor holding member 22 that holds the position detection sensor 23 at the tip is provided. The position detection sensor 23 detects a distance to the supported surface of the workpiece W, and the detected position data of the supported surface is transmitted to a position calculation unit 31 described later.
[0018]
The cover member 24 is formed of a substantially cylindrical member disposed on the housing 11, and the push-up member 20 is fitted therein. The push-up member 20 is also formed of a cylindrical member, and an internal thread is formed on the inner peripheral surface thereof, and this is screwed with an external thread formed on the outer peripheral surface of the drive shaft 19. A substantially ring-shaped support member 21 is placed on the upper end surface of the push-up member 20, and a plurality of steel balls 28 and an O-ring 29 provided so as to be sandwiched between the outer peripheral surface of the push-up member 20. The support member 21 is engaged with the push-up member 20 by the action. Further, the upper end surface of the push-up member 20 is formed as a spherical concave surface, while the lower end surface of the support member 21 in contact with this is formed as a spherical convex surface, and the lower end surface of the support member 21 is above the upper end surface of the push-up member 20. By sliding, the angle of the support surface 21a of the support member 20 can be changed. Further, a plurality of V-shaped grooves 25 are provided on the lower outer peripheral surface of the push-up member 20, and the push-up member 20 is rotated by the steel balls 26 pressed against the grooves 25 by screws 27. It is designed to be locked. Thus, when the drive shaft 19 rotates about the axis, the push-up member 20 screwed with the drive shaft 19 moves in the axial direction, and the support member 21 moves in the same direction.
[0019]
The servo motor 13 is attached to the bottom surface of the housing 11, and the gear 15 is connected to the output shaft 13a. When the servo motor 13 is driven and the output shaft 13a rotates, the gear 15 connected thereto rotates about the shaft center, and the gear 16 engaged with the gear 15 rotates together with the drive shaft 19 about the shaft center. The servo motor 13 has a conventionally known configuration including a rotary encoder (not shown), and its operation is controlled by the control device 30.
[0020]
As shown in FIG. 2, the control device 30 includes a position calculation unit 31, a position control unit 32, and an overload detection unit 33. The position calculation unit 31 receives the detection data from the position detection sensor 23, calculates the supported surface position of the workpiece W, and transmits the calculated position data to the position control unit 32. The position control unit 32 feedback-controls the servo motor 13 based on the position data of the supported surface received from the position calculating unit 31, and the position of the support surface 21a of the support member 21 matches the position of the supported surface. The support member 21 is moved as described above. The correlation between the position data detected by the position detection sensor 23 and calculated by the position calculation unit 31 and the position of the support surface 21a is obtained in advance experimentally, and the position control unit 32 obtains this correlation. The servo motor 32 is feedback-controlled based on the obtained correlation. In addition, the overload detection unit 33 receives and monitors data on the control current value output from the position control unit 32 to the servomotor 13 and the control current exceeds a preset allowable range. Then, it is determined that there is an overload, and this is output to the outside, for example, an NC device that numerically controls the machine tool.
[0021]
According to the support device 10 of the present example having the above configuration, first, the position detection sensor 23 detects the position of the supported surface of the workpiece W that has been transferred to the mounting position by appropriate transfer means such as a workpiece transfer robot, The detected position data is transmitted to the position calculation unit 31. At this time, it is assumed that the support member 21 is positioned in advance downward so that the support surface 21a does not contact the supported surface of the workpiece W. Next, the position calculation unit 31 calculates the supported surface position from the received position data, and transmits this to the position control unit 32. Then, the position control unit 32 feedback-controls the servo motor 13 to move the support surface 21a of the support member 21 in the axial direction so that it is in the same position as the supported surface. As a result, the support surface 21 a of the support member 21 comes into contact with the supported surface of the work W, and the work W is supported by the support device 10. At this time, as described above, since the support member 21 is provided so that the angle of the support surface 21a can be changed, the supported surface of the work W is the mounting reference surface (in the present example, the positioning is determined). Even if it is not parallel to the upper surface of the base 103b of the member 103, the angle of the support surface 21a is changed following this supported surface, so that the work W is supported by the entire support surface 21a. And the support becomes stable.
[0022]
And after supporting the workpiece | work W with the support apparatus 10 in this way, the hydraulic clamper 105 is driven and the workpiece | work W is clamped and fixed between the clamp member 107 and the support apparatus 10. FIG. Thereafter, the workpiece W is appropriately machined, and the machining load acting on the workpiece W at that time is detected by the overload detection unit 33, and when the machining load exceeds the allowable range, it is determined as overload. A determination signal is output to an external device such as an NC device.
[0023]
When a downward force due to a machining load acts on the support member 21, a torque in the direction opposite to the driving direction acts on the servo motor 13 via the push-up member 20, the drive shaft 19, the gear 16, and the gear 15. The servo motor 13 is feedback-controlled by the position control unit 32 so that its rotational position does not change. However, when the torque acts on the servo motor 13, the control in the position control unit 32 prevents the rotational position from changing. The current is increased. Therefore, this control current is monitored, and when this is outside the preset allowable range, it can be determined that an excessive machining load is acting on the workpiece W. Therefore, in this example, when the control current is outside the preset allowable range, the overload detection 33 determines that the load is overloaded.
[0024]
Thus, according to the support device 10 of this example, the support member 21 is moved by the drive of the servo motor 13 so that the support surface 21a of the support member 21 coincides with the position of the supported surface of the workpiece W, and the support member 21 is supported. Since the surface 21a is provided so as to contact the supported surface of the workpiece W, there are variations in the dimensions of the workpiece W, and when the workpiece 21 is transferred to the mounting position, the supported surface position varies depending on the individual workpiece. Even if it is a case, the support surface 21a of the said supporting member 21 can be correctly contact | abutted to the to-be-supported surface of a workpiece | work. Therefore, it is possible to minimize the clamping distortion that occurs when the workpiece W is clamped by the hydraulic clamper 105. By making the clamp distortion as small as possible in this way, it is possible to reduce the processing error accompanying the clamp distortion, and to realize high-precision processing such as the order of 10 ⁻³ mm or 10 ⁻⁴ mm. it can.
[0025]
In addition, since an excessive machining load acting on the workpiece W is detected by the overload detection unit 33, when an excessive machining load is detected, the tool feed speed or rotational speed is reduced, or It is possible to take measures such as changing tools. As a result, the workpiece W is displaced due to an excessive machining load, and the workpiece W becomes a defective product, or the workpiece W is detached from the workpiece mounting jig 1 to damage the tool, the workpiece mounting jig 1 or the machine tool. It is possible to prevent the occurrence of inconvenience and to realize stable machining. If the machining load detected by the overload detection unit 33 is smaller than the reference value, the machining time can be shortened by conversely increasing the tool feed speed or rotation speed.
[Brief description of the drawings]
FIG. 1 is a front view showing a workpiece mounting jig according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view in the direction of arrow AA in FIG.
FIG. 3 is a front view showing a conventional workpiece mounting jig.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Work attachment jig 10 Support apparatus 11 Housing 13 Servo motor 15 Gear 16 Gear 19 Drive shaft 20 Push-up member 22 Sensor holding member 23 Position detection sensor 30 Control apparatus 31 Position calculation part 32 Position control part 33 Overload detection part

Claims (1)

A support device that is provided on an attachment jig and supports a workpiece attached to the attachment jig,
A support member that contacts the workpiece and supports the workpiece;
A drive means that includes a servo motor, and that drives the support member forward and backward in a direction orthogonal to the support surface of the support member that supports the workpiece by the driving force of the servo motor ;
Position detecting means for detecting the position of the supported surface of the workpiece transferred to the mounting position of the mounting jig and supported by the support member;
A position for driving and controlling the servo motor based on the position data detected by the position detecting means to move the support member so that the support surface position of the support member coincides with the supported surface position of the workpiece. and control means,
The position control means feedback-controls the servomotor so that the support surface position of the support member is located at a target position that coincides with the supported surface position of the workpiece, and a control current related to the feedback control is within an allowable range. A workpiece support device configured to determine that an excessive machining load has occurred when the value exceeds .

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