JPH10202456A - Clamp device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clamp device capable of giving a workpiece of high flatness at the time of milling a thin plate type workpiece. SOLUTION: This clamp device has a plurality of main clamps 10 for holding the upper and reverse sides of a workpiece W at least at a position nearer the lengthwise center thereof and a plurality of natural clamps 20 arranged around the clamping positions of the main clamps 10 for bearing the reverse side of workpiece machining surface. The main clamps 10 have a point-support structure, and each of the natural clamps 20 is adjustable in support pressure for the reverse side of the workpiece W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clamp device for holding a workpiece to be machined, and more particularly to a clamp device which is preferably applied to flat machining of a thin plate-like workpiece using a milling machine.

[0002]

2. Description of the Related Art When a camshaft housing (work) of an automobile engine is subjected to, for example, grinding of a mounting hole, the position of a work support and the pressure of a clamp for holding the work are set to certain values. It has been proposed to perform processing and adjust the position of the work support and the clamping pressure of the work based on the result of measuring the dimensions after the processing (see, for example, Japanese Patent Application Laid-Open No. 7-164,216). ).

Accordingly, the camshaft housing, which is a work, is subjected to grinding in a state substantially similar to a state where the camshaft housing is assembled to the cylinder head.

[0004]

However, the technique disclosed in the above-mentioned publication cannot be directly applied to the plane machining of a thin plate component such as a control valve body by a milling machine, among the engine assembly components. . This is because the cutter of the milling machine and the clamp interfere with each other.

[0005] For this reason, when milling a thin plate-shaped control valve body W, as shown in FIG.
It has been studied to support the natural clamps N1 to N4 from the back side of the processing surface, in addition to the main clamp at M3, and the purpose of preventing vibration during processing.

However, the work W after milling is
When the flatness of the workpiece W is measured at 20 points HE1 to HE20 shown in FIG. 9, as shown by flatness contour lines in FIG. 8, the workpiece W is supported by the natural clamps N1 to N4. The result was that the center was recessed downward.

The present invention has been made in view of such problems of the prior art, and provides a clamp device capable of obtaining a work having high flatness when milling a thin plate-like work. The purpose is to:

[0008]

According to a first aspect of the present invention, there is provided a clamping apparatus for holding a workpiece when milling a thin plate-like workpiece. A plurality of main clamps for gripping the front and back of the workpiece at least at a position near the center in the longitudinal direction, and a plurality of natural clamps arranged around the gripping position of the main clamp and supporting a back surface of the work surface of the workpiece. It is characterized by having.

When a thin plate-shaped workpiece is milled, a concave distortion is generated on the processing surface due to a clamping stress or a cutter stress in addition to the residual stress of the workpiece itself. In addition to gripping the front and back of the work at least at a position near the center in the longitudinal direction, a natural clamp is arranged around the gripping position of the main clamp and supports the back surface of the work surface of the work, so that processing by cutter stress is performed. The distortion can be suppressed, and the flatness of the work can be increased.

[0010] The clamp device according to claim 2 is characterized in that at least one of the grip portions of the main clamp has a point support structure. By using the main clamp as a point support, distortion due to the main clamp stress can be suppressed. In this case, it is more preferable that both of the grips of the main clamp are point-supported, but even if only one of the grips is point-supported, a considerable distortion suppressing effect can be obtained.

Further, in the clamp device according to the present invention, each of the natural clamps further includes a natural clamp pressure setting means for adjusting a support pressure on the back surface of the work, and a pressure sensor for detecting the support pressure. It is characterized by the following. Since there is a correlation between the natural clamp pressure and the flatness, a work having a higher flatness can be obtained by adjusting the natural clamp pressure. In particular, since the respective clamping pressures of the natural clamps can be individually adjusted, the work can be made highly flat over the entirety.

Further, in the clamp device according to a fourth aspect, each of the natural clamps further includes an operation abnormality sensor. By detecting an abnormal operation of the natural clamp, it is possible to prevent a decrease in flatness due to an unexpected natural clamp pressure acting.

[0013] Further, the clamping device according to claim 5 is characterized in that:
Flatness measuring means for measuring the flatness of the workpiece, and natural clamp pressure calculating means for calculating a support pressure of the natural clamp based on a measurement result by the flatness measuring means, wherein the natural clamp pressure setting The means is controlled by an output signal from the natural clamp pressure calculating means.

In the clamp device according to the fifth aspect, the flatness of the processed workpiece is measured by the flatness measuring means, and the measurement result is taken into the natural clamp pressure calculating means to determine an appropriate supporting pressure of the natural clamp. calculate. Then, the obtained appropriate support pressure is output to the natural clamp pressure setting means, and the next work is supported by the support pressure. As described above, by performing the feedback control, it is possible to obtain a work having a higher flatness.

[0015]

According to the clamp device of the first aspect,
Since the setting positions of the main clamp and the natural clamp are appropriate, processing distortion due to cutter stress can be suppressed, and the flatness of the work can be increased.

According to the clamp device of the second aspect, since the main clamp is performed by the point support, the distortion due to the main clamp stress can be suppressed, and a work with high flatness can be obtained.

According to the third aspect of the present invention, since the natural clamping pressure can be adjusted, a work having higher flatness can be obtained. In particular, since the respective clamping pressures of the natural clamps can be individually adjusted, the work can be made highly flat over the entirety.

According to the clamp device of the fourth aspect, since the operation abnormality of the natural clamp is detected, it is possible to prevent a decrease in flatness due to an unexpected natural clamp pressure acting.

According to the fifth aspect of the present invention, the flatness of the processed workpiece is measured by the flatness measuring means, and the measured result is feedback-controlled to perform the next clamping. At a high pass rate.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. First, the mechanical system of the clamp device of the present embodiment will be described. FIG. 1 is a plan view showing setting positions of a main clamp and a natural clamp in the present embodiment, FIG. 2 is a plan view showing a clamping device of the present embodiment, FIG. 3 is a side view thereof, and FIG. FIG. 5 is a side view showing a natural clamp according to the embodiment, showing a main part of the clamp.

The clamp device according to the present embodiment, when milling one main surface (front surface side in the drawing) of a substantially rectangular, thin plate-shaped control valve body W as shown in FIGS. This is a clamp device for holding W.

This clamp device has three main clamps 10 and six natural clamps 20 as shown in FIGS. 1 and 2, and the main clamp 10 It is arranged at three positions MS1 to MS3 from the end to the center from the ends. On the other hand, the natural clamps 20 are located around the positions MS1 to MS3 where the main clamps 10 are provided.
It is arranged at S6. For example, the main clamp MS1
Around the natural clamp NS1, NS2, NS3
Are arranged, and natural clamps NS4 and NS5 are arranged around the main clamp MS2, and natural clamps NS5 and NS6 are arranged around the main clamp MS3.

As shown in FIG. 4, each of the main clamps 10 grips the front and back surfaces of the work W.
The sheet 19 is in contact with the back surface of the work W, while the swing arm 13 is in contact with the surface of the work W. The tip of the swing arm 13 is formed in a curved surface so as to support a point (see the point support portion 15). The swing arm 13 is pivotally supported at the tip of the plunger 11, and a link 12 is provided at the center of the swing arm 13. Therefore, when the plunger 11 comes and goes, the swing arm 13 is opened and closed by the link 1, and the work W is gripped and released. An input port 14 applies a fluid pressure for locking the swing arm 13.

On the other hand, the natural clamp 20
As shown in FIG. 3, abuts against and supports the back surface of the work W. As shown in FIG. 5,
A pad 24 is attached to the tip of the plunger 23. The pad 24 comes into contact with the back surface of the work W. The plunger 23 moves in and out by the flow of the fluid from the plunger pressure input port 21 and is locked by the flow of the fluid from the lock pressure input port. The natural clamp 20 has a built-in pressure sensor 26, which detects the clamp pressure of the plunger 23 and feeds it back to a natural clamp pressure setting unit described later. Further, the natural clamp 20 is provided with an operation abnormality sensor 24 for detecting an operation abnormality of the plunger 23, and feeds back to the above-mentioned control unit of the milling machine.

In FIG. 2, positioning bars 31 and 3 for positioning the work W are provided at one edge of the work W.
2 are provided.

Next, a control system of the clamp device according to the present embodiment will be described. FIG. 6 is a block diagram showing a configuration of a control system of the embodiment of the clamp device of the present invention, and FIG. 7 is a flowchart showing a control procedure of the block diagram shown in FIG.

First, regarding the main clamp 10, a signal from the milling machine control unit 107 is input to the main clamp drive unit 101, whereby the plunger 11 operates to open and close the main clamp unit 102.

On the other hand, the clamp device of the present embodiment has a three-dimensional shape measuring unit 109 for measuring the flatness of the work W.
The measurement result is output to the flatness determination unit 110. The flatness determination unit 110 obtains a difference in flatness between the natural clamp positions NS1 to NS6 based on, for example, the flatness of the main clamp positions MS1 to MS3 shown in FIG. This determination result is output to the natural clamp pressure calculator 111.

In the natural clamp pressure calculating section 111,
The natural clamp pressure is calculated based on the following equation (1), and the result is output to the natural clamp pressure setting unit 108 of each natural clamp 20.

[0030]

ΔMAX (cantilever) = WL3 / 3EI (1) where W is load, L is overhang distance, E is longitudinal modulus, I is section modulus, and I = bh3 / 12.
(Where b: width, h: effective height). Also,
L (i), E (i), and I (i) are unique values for each clamp position. From the above equation (1), W (i) = δMAX
・ 3EI / L3.

For example, the natural clamp N shown in FIG.
The pressure set value of S1 is obtained by subtracting HE4 corresponding to the main clamp position MS1 from HE1 corresponding to NS1 at the flatness measurement position shown in FIG.
Next, W (i) = δMAX which is a modified expression of the above expression (1)
A load W (i) is obtained from 3EI / L3, and a natural clamp pressure corresponding to this load is calculated.

In the natural clamp pressure setting section 108,
It takes in the detection value from the pressure sensor 26 built in the natural clamp 20, outputs a command signal to the natural clamp drive unit 105 based on the command signal from the natural clamp pressure calculation unit 111, and outputs the natural clamp unit 104, The plunger 23 is operated.
As a result, the support pressure of the natural clamp is feedback-controlled to an appropriate value.

The detection signal from the natural clamp operation abnormality sensor 25 provided in the natural clamp 20 is output to the milling machine control unit 107, and when abnormal, is displayed on the milling machine control unit 107.

Next, the operation will be described. As shown in FIG.
3D shape measuring unit 1
09 (Step 1), and the flatness determination unit 110 determines flatness (Step 2). If the measured flatness satisfies the standard, the process proceeds to step 7, but if the measured flatness does not satisfy the standard, the process proceeds to step 6 and the natural clamp pressure calculation unit 111 calculates the natural clamp pressure according to the above-described procedure. And natural clamp pressure setting unit 10
In step 8, an appropriate natural clamping pressure is set based on this (step 6).

In parallel with this, the work W is positioned (step 4), and the main clamp 10 is locked (step 5).

In step 7, each natural clamp 20 set to an appropriate pressure is operated and locked (step 8). At this time, the output signal of the operation abnormality sensor 25 is monitored (step 9), and if an abnormality occurs, an abnormality is displayed on the milling machine control unit 107 (step 10).

With the above, the setting by the main clamp 10 and the natural clamp 20 is completed. In step 11, the surface of the work W is milled. When the milling is completed, first, each natural clamp 20 is released (step 12), and each main clamp 10 is released (step 13). When the holding of the work W is released, the work W is moved (step 1).
4), the flatness of the milling process is measured by the three-dimensional shape measuring unit 109.
(Step 15), and returns to Step 1.

When the above-mentioned thin plate-shaped workpiece W is milled, concave distortion is generated in the processing surface due to clamping stress or cutter stress in addition to the residual stress of the workpiece itself. 1
0 grips the front and back of the work W at least at a position near the center in the longitudinal direction of the work W, and the natural clamp 20 is disposed around the holding position of the main clamp 10 so that the back surface of the processing surface of the work W is I support it,
Processing distortion due to cutter stress can be suppressed, and the flatness of the work W can be increased.

In the clamp device of the present embodiment, since the main clamp 10 is supported at a point, distortion due to the main clamp stress can be suppressed. In addition, since each natural clamp 20 can adjust the supporting pressure on the back surface of the work W, a work with higher flatness can be obtained. This is because there is a correlation between the natural clamp pressure and the flatness. In particular, since the respective clamping pressures of the natural clamps 20 can be individually adjusted, the work W can have a high flatness over the whole.

Further, in the clamp device of the present embodiment, since the operation abnormality sensor is provided for each natural clamp 20, an operation abnormality of each natural clamp 20 is detected, whereby an unexpected natural clamp pressure is applied. Therefore, it is possible to prevent a decrease in flatness due to this.

Further, the clamp device of the present embodiment measures the flatness of the work W processed by the three-dimensional shape measuring unit 109, and takes the measurement result into the natural clamp pressure calculating unit 111 to perform feedback control.
A work with higher flatness can be obtained.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a plan view showing set positions of a main clamp and a natural clamp in an embodiment of a clamp device of the present invention.

FIG. 2 is a plan view showing an embodiment of the clamp device of the present invention.

FIG. 3 is a side view showing an embodiment of the clamp device of the present invention.

FIG. 4 is a main part side view showing a main clamp according to the embodiment of the clamp device of the present invention.

FIG. 5 is a side view showing a natural clamp according to the embodiment of the clamp device of the present invention.

FIG. 6 is a block diagram showing a configuration of a control system of the embodiment of the clamp device of the present invention.

FIG. 7 is a flowchart showing a control procedure of the block diagram shown in FIG. 6;

FIG. 8 is a plan view showing setting positions of a main clamp and a natural clamp of a reference clamping device.

FIG. 9 is a plan view showing an example of a measurement position for measuring flatness.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Main clamp 15 ... Point support part 20 ... Natural clamp 25 ... Abnormal operation sensor 26 ... Pressure sensor 108 ... Natural clamp pressure setting means 109 ... Three-dimensional shape measuring part (flatness measuring means) 111 ... Natural clamp pressure calculating part ( Natural clamp pressure calculating means) W: Workpiece MS1 to MS3: Main clamp position NS1 to NS6: Natural clamp position

Claims (5)

[Claims] 1. A clamp device for holding a work when milling a thin plate-like work, comprising: a plurality of main clamps for gripping front and back of the work at least at a position near a center in a longitudinal direction of the work; A plurality of natural clamps disposed around a gripping position of the main clamp and supporting a back surface of a processed surface of the work. 2. The clamp device according to claim 1, wherein at least one of the grip portions of the main clamp has a point support structure. 3. Each of said natural clamps comprises:
The clamping device according to claim 1, further comprising a natural clamp pressure setting unit that adjusts a support pressure on the back surface of the work, and a pressure sensor that detects the support pressure. 4. Each of said natural clamps comprises:
The clamping device according to claim 1, further comprising an operation abnormality sensor. 5. A flatness measuring means for measuring the flatness of the work, and a natural clamp pressure calculating means for calculating a support pressure of the natural clamp based on a measurement result by the flatness measuring means, The clamping device according to claim 3, wherein the natural clamp pressure setting unit is controlled by an output signal from the natural clamp pressure calculation unit.