JP3143822B2 - Product accuracy inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a product which is obtained by clamping two or more workpieces set on a jig on which a plurality of clamp units are mounted by these clamp units, and connecting the workpieces in this state. It relates to a method for checking accuracy.

[0002]

2. Description of the Related Art Conventionally, according to Japanese Patent Application Laid-Open No. Hei 1-153387, a clamp unit is made movable, and at the first time, a work is clamped to a position where the clamp unit is positioned at a predetermined reference position determined from design data. Combine
Next, the accuracy of the product assembled by this connection is optically measured, the position of the clamp unit is corrected based on the measurement result, the next work is connected, and the accuracy measurement is performed. A method is known in which the process is repeated until the product is obtained.

[0003]

In the optical precision measurement as in the above-mentioned conventional example, there is a problem that the measurement equipment becomes large and the equipment cost increases. The present invention has been made in view of the above points,
It is an object of the present invention to provide a method capable of inspecting the accuracy of a product with simple equipment on a jig.

[0004]

Means for Solving the Problems In order to solve the above problems,
The present invention relates to a fixed clamp piece and the fixed clamp piece.
Two or more workpieces set on a jig equipped with a plurality of clamp units having movable clamp pieces that can be freely opened and closed can be moved by the movable clamps by the clamp units.
In the method of inspecting the accuracy of the assembled product by closing and clamping the clamp pieces and joining the workpieces in this state, at least a part of these clamp units is constituted by a movable clamp unit capable of controlling movement in the clamping direction. to the detection means for detecting a contact with the workpiece fixing clamp pieces of the movable clamp unit provided, after work-binding, soluble
The movable clamp unit is unclamped by opening the moving clamp piece and once separated from the product, and then the movable clamp unit is approached to the product, and the point of contact of the fixed clamp piece with the product is detected by the signal from the detecting means. The distortion of the product is measured from the position of the movable clamp unit at the time of the contact.

If the product has distortion, the position (contact position) of the movable clamp unit at the time of contact with the product deviates from a predetermined reference position, and thus the distortion of the product can be measured from the contact position. In the present invention, it is only necessary to provide a detection means such as a load cell for detecting contact with the product on the fixed clamp piece of the movable clamp unit. Therefore, it is possible to inspect the accuracy of the product with simple equipment on a jig. ,
Productivity is improved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention is applied to a precision inspection of a product W having a closed cross-sectional shape which is assembled by joining two works Wa and Wb shown in FIG. 1 by spot welding, arc welding, bonding or the like. The form will be described.

[0007] Here, any of the workpieces Wa and Wb is shown in FIG.
When there is a strain δ as shown in FIG. 2A, the workpiece is forcibly bent by the strain δ as shown in FIG. W
When the workpiece W is unclamped after being joined to each other, the product W has a strain δ ′ due to springback due to the strain δ of the work.
Occurs.

In this case, the workpieces Wa and Wb are clamped, and then the workpiece is fixed to a predetermined correction amount A as shown in FIG.
When the workpieces are joined together in this state, the product W springs back by the correction amount A at the time of unclamping as shown in FIG. 2 (e), so that no distortion remains in the product W. There is a unique relationship between the correction amount A and the distortion amount δ of the work. Thus, by obtaining an empirical formula representing the relationship between the work distortion amount δ and the correction amount A, measuring the work distortion amount δ, and substituting this into the experimental expression, the correction amount A can be calculated, and the work Wa, Since the workpieces are joined by further bending Wb by the correction amount A, no distortion remains in the product W. However, the correction amount A calculated from the empirical formula includes an error. Therefore, it is desired to inspect the accuracy of the product W and correct the calculation of the correction amount A by learning control.

FIG. 3 shows equipment capable of automatically performing the above processing. In the figure, reference numeral 1 denotes a jig. On the jig 1, a pair of reference clamp units 2 and 2 for clamping one ends of the works Wa and Wb at fixed positions and a middle part of the works Wa and Wb are clamped. to, the first movable clamp units 3 ₁ mobile controllable pair vertically, 3 _1, workpiece Wa, clamping the other end of the Wb, the second movable clamp unit 3 of the mobile controllable pair vertically _2, 3 ₂ and is provided.

Each of the movable clamp units 3 ₁ and 3 ₂ is shown in FIG.
As shown in the figure, a lower fixed clamp piece 31 fixed to the bracket 30 and an upper movable clamp piece 32 pivotally mounted on the bracket 30 so as to be able to open and close vertically are provided. The piston rod 33a of the pressure cylinder 33, which is freely mounted on the shaft, is
2, when the movable clamp piece 32 is closed by the operation of the pressurizing cylinder 33, the workpieces Wa, Wb are clamped between the contact tips 31a, 32a attached to the clamp pieces 31, 32, respectively. I have.

The above arrangement is the same as that of the reference clamp unit 2. However, the movable clamp units 3 ₁ and 3 ₂ further include a moving mechanism 34 for moving the bracket 30 in the vertical direction, ie, the clamping direction, and two clamp pieces 31. , 32, the fixed clamp piece 3 in the illustrated example.
Detecting means 35 for detecting a pressing reaction force of the workpiece
And

The moving mechanism 34 includes a lifting rod 341 having a mounting base 341a for the bracket 30 at an upper end, and a lower end of the lifting rod 341. A nut 342, which is screwed to a threaded rod 341b attached to the casing 340, is rotatably supported on the lower inner periphery of the casing 340 via a holder 342a, and a belt 34
3a, a pulley 343b on the output shaft connected to the servomotor 343 as a drive source. The nut 342 is rotated forward and reverse by the servomotor 343, so that the bracket 30 moves up and down via the lifting rod 341. Be moved. A spline groove (not shown) is formed on the outer peripheral surface of the elevating rod 341, and a ball spline sleeve 344 containing a ball that engages with the spline groove is fitted in the casing 340 by a key 344 a so as not to rotate. It is inserted.

The detecting means 35 includes a fixed clamp piece 31.
And a load cell embedded in the
1a is fixed to the fixed clamp piece 31 by the shaft portion 31 of the tip 31a.
b so as to be freely movable in the vertical direction,
Is brought into contact with the load cell 35, so that the load cell 35 receives the pressing reaction force of the work via the contact tip 31a. Note that the contact tip 31a has a shaft portion 31b.
Is fixed to the fixed clamp piece 31 by a circlip 31c attached thereto, and the chip insertion portion 31d of the fixed clamp piece 31 is detachably attached to the main body of the clamp piece 31 to separate the chip insertion portion 31d. By removing the circlip 31c in this state, the contact tip 31a can be replaced.

When the workpieces Wa and Wb are combined, FIG.
As shown in, first, the work Wa by the reference clamp units 2, while clamping the Wb, clamping the workpiece Wa, and Wb while position each movable clamp units 3 _1, 3 ₂ to a predetermined reference position in the vertical direction ( S1).
In this case, if any of the workpieces Wa and Wb is distorted,
The detected value of the pressing reaction force detected by the load cell 35 is deviated from the reference value of the pressing reaction force by the force required to bend the work by the distortion amount δ. Therefore, the distortion amount δ of the work can be calculated from the deviation of the detected value of the pressure reaction force from the reference value.

Therefore, in the apparatus shown in FIG. 3, the signal of the load cell 35 of each of the movable clamp units 3 ₁ and 3 ₂ is transmitted to the personal computer 4, and the computer 4 outputs the signal based on the detected value of the pressing reaction force. The amount of strain δ of the work at the clamp location of each movable clamp unit 3 ₁ , 3 ₂
(S2), and based on the distortion amount δ,
The straightening amount A of the workpiece at each clamp location required to prevent distortion from remaining in the product W is calculated (S3), and the data of the straightening amount A is transmitted to the control panel 5 for the jig 1, and The servo motor 343 of the moving mechanism 34 of each movable clamp unit 3 ₁ , 3 ₂ is actuated by a command signal from the control panel 5, and each movable clamp unit 3 ₁ , 3 ₂ is moved from its reference position by the movement of its bracket 30. In this state, the workpieces Wa and Wb are connected to each other by a welding robot or the like (not shown) (S4).
5).

After the connection, the reference clamp unit 2
With the product W clamped, the movable clamp units 3 ₁ and 3 ₂ are unclamped and moved down, and the movable clamp units 3 ₁ and 3 ₂ are separated below the product W (S
6). In this case, if no distortion remains in the product W, each clamp portion of the product W springs back to the reference position.

Next, the movable clamp units 3 ₁ , 3 ₂ are moved upward while the personal computer 4 monitors the signals of the load cells 35 of the movable clamp units 3 ₁ , 3 ₂ . In this case, when the contact tip 31a of the fixed clamp piece 31 of the movable clamp unit 3 _1, 3 ₂ contacts the product W, the detection signal of the load cell 35 is changed. When the movable clamp units 3 ₁ and 3 ₂ move upward, the input gain of the signal of the load cell 35 is increased, and the detected value of the pressing reaction force becomes a predetermined minute value (for example, 0.3 kg). the point in time as the contact point for the product W of the contact tip 31a, detects each of the movable clamp units 3 ₁ at this point, 3 _second position (contact position) the signal from the servo motor 343 (S7).

If distortion remains in the product W, the contact position is shifted from the reference position by the amount of distortion of the product W.
Thus, the distortion of the product W can be measured from the deviation of the contact position from the reference position. After the accuracy inspection of the product W is performed in this way (S8), if distortion remains in the product W, a correction formula is added to the calculation formula of the correction amount A based on the distortion amount δ of the work, and the correction is performed by learning control. The quantity A can be calculated correctly (S9).

As described above, the movable clamp units 3 ₁ and 3 ₂
The embodiment has been described in which the workpieces Wa and Wb are coupled with each other while being displaced from the reference position by the correction amount A calculated based on the distortion amount δ of the workpiece, but the movable clamp units 3 ₁ and 3 ₂ are described. the combining while work together and positioned at a predetermined reference position, a distortion of the product W after binding measured from the contact position to the same manner as described above the movable clamp units 3 _1, 3 ₂ products W, on the measurement result The reference positions of the movable clamp units 3 ₁ and 3 ₂ may be corrected based on the feedback method. In this case, there is no need to measure the amount of distortion of the work from the pressure reaction force during clamping,
Therefore, the movable clamp units 3 ₁ and 3 ₂ may be provided with detection means such as a proximity switch for detecting only contact with the product, instead of the load cell 35.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a target work of the present invention.

2 (a) to 2 (e) are diagrams showing the principle of distortion generation and the principle of distortion removal of a product.

FIG. 3 is a perspective view of an example of equipment used for carrying out the present invention.

FIG. 4 is a sectional view of a movable clamp unit.

FIG. 5 is a flowchart showing an example of a processing procedure of the present invention.

[Explanation of symbols]

Wa, Wb the workpiece W products 1 jig 3 _1, 3 ₂ movable clamp unit 34 moving mechanism 35 load cell (detecting means)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yutaka Asano 1-10-1 Shin-Sayama, Sayama-shi, Saitama Prefecture Inside Honda Engineering Co., Ltd. (72) Inventor Isao Kudou 1-10-1 Shin-Sayama, Sayama-shi, Saitama Prefecture (56) References JP-A-3-196944 (JP, A) JP-A-59-156633 (JP, A) JP-A-1-115535 (JP, A) JP-A 1-153388 (JP, A) JP-A-6-344026 (JP, A) JP-A-61-172609 (JP, U) JP-A-4-54509 (JP, U) JP-A-60-28994 (JP, U) ( 58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 5/00 G01B 21/32 B23K 37/04

Claims (1)

(57) [Claims] A fixed clamp piece and a pair of fixed clamp pieces are provided.
And two or more workpieces set on a jig equipped with a plurality of clamp units having movable clamp pieces that can be freely opened and closed .
In the method of inspecting the accuracy of the assembled product by closing and clamping the lamp piece and joining the workpieces in this state,
At least a part of these clamp units is constituted by a movable clamp unit that can be moved and controlled in the clamp direction, and a fixed clamp piece of the movable clamp unit is provided with a detecting unit for detecting contact with the work, and after the work is joined,
The movable clamp unit is unclamped by opening the movable clamp piece and once separated from the product, and then the movable clamp unit is brought close to the product, and the point of contact of the fixed clamp piece with the product is detected by the signal from the detection means. And measuring the distortion of the product from the position of the movable clamp unit at the time of the contact.