JPH06328329A - Screwing device - Google Patents

Abstract

PURPOSE:To adjust pressure force at high accuracy, and give pressure force within fixed accuracy even a pressurized object is deformed. CONSTITUTION:Second work W2 is placed on first work W1 having a screw hole, and the second work W2 is screwed to the first work W1 by the rotation of a bit member 26a. At the time of screwing, an upper side elevating member 9 is lowered by a servo motor 6 and a lower side elevating member 21 is pushed down by a pressure member 11. The bit member 26a is applied to a screw to perform screwing by given pressure force. A load applied to the lower side elevating member 21 is detected by a load cell 34. The upper side elevating member 9 is position-controlled by a control unit 41 until this load becomes a given value (target value).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION In the present invention, a second work is placed on a first work having a screw hole, and a second work is performed by a bit member.
The present invention relates to a screw tightening device for screwing a work of (1) to a first work.

[0002]

2. Description of the Related Art Conventionally, in a screw tightening device for placing a second work on a first work having a screw hole and screwing the second work to the first work by a bit member, the first work It is necessary to press the second work on top with a constant pressure, and normally a DC servo motor is used to apply such pressure. The current flowing through the servo motor is limited and the rotation is stalled to control the applied pressure.

[0003]

However, when the second work is deformed, the second work does not follow up due to the deflection of the mechanism and backlash, and the servo motor generates a prescribed torque. In some cases, the specified torque was not generated, and the variation was large.

Further, as described in, for example, Japanese Patent Laid-Open No. 63-47030, a disc is placed on a disc rotary motor having screw holes, and a bit member is rotated to dispose the disc at four positions with respect to the disc rotary motor. In order to fasten the disc, first tighten the two dummy bolts with the bit member at two places to bend the disc retainer, then apply the spring force to the disc retainer, and tighten the two bolts at the remaining two places. To do. After that, it is known to remove the two dummy bolts and tighten the first two places with two bolts, but this method does not adjust the length of the spring delicately with high precision. It cannot adjust the pressure.

Further, as described in, for example, Japanese Utility Model Laid-Open No. 63-74226, the preload boss is used as the fixed side.
A preload screw including a load meter for detecting a preload applied to the bearing via the preload source, a preload source for preloading the shaft side, and a control device for controlling the preload source based on the measured value of the load meter. A tightening device is also known,
The performance of the preload source becomes the accuracy of pressurization as it is.
When the pre-pressed product is deformed, it may not be possible to pressurize it while maintaining the applied pressure at a certain accuracy.

The present invention provides a screw tightening device capable of adjusting a pressing force with high accuracy and applying a pressing force within a certain accuracy even when a pressed object is deformed.

[0007]

According to the present invention, there is provided a screw tightening device for placing a second work on a first work having a screw hole and tightening the second work with the first work by a bit member. Is assumed.

According to a first aspect of the present invention, there is provided an apparatus main body, an upper elevating member which is provided in the apparatus main body so as to be able to ascend and descend and whose vertical position relative to the apparatus main body is adjustable, and is supported so as to be vertically movable with respect to the upper elevating member. Pressure member, a spring member interposed between the pressure member and the upper and lower elevating member, and constantly urging the pressure member downward, and below the pressure member with respect to the apparatus main body. A lower elevating member that is movably supported, whose vertical position is adjusted by the pressure applied by the pressing member, and that rotatably supports the bit member; and an upper elevating member that is linked to the upper elevating member and that is relative to the apparatus body. The configuration is such that adjustment means for adjusting the vertical position is provided.

According to a second aspect of the present invention, the pressure sensor for detecting the pressure applied to the lower lifting member by the pressure member, and the adjusting means for adjusting the output of the pressure sensor to adjust the upper lifting member. And a control means for controlling the vertical position.

[0010]

According to the invention of claim 1, when the screw is fastened, the upper elevating member is lowered by the adjusting means and the lower elevating member is pushed down by the pressing member. The bit member is applied to the screw, and the screw tightening is performed with a predetermined pressing force.

According to the second aspect of the present invention, the load acting on the lower lifting member is detected by the pressure sensor. This load is a load via the spring force of the spring member, and this value is taken into the control means. The position of the upper lifting member is controlled by the adjusting means until the load reaches a predetermined value (target value).

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In FIG. 1 showing a schematic structure, 1 is a screw tightening device, and a second work W2 is provided on the upper surface of the first work W1.
Is placed and they are simultaneously tightened with four screws 2, .... The first work W1 has a central convex portion a having a concave portion a1 at the upper end and a circular convex portion b located at the peripheral edge with a constant distance from the central convex portion a1. Second work W
2 is a reverse hat-shaped cross section, and has a bottom surface portion c having a through hole c1 into which the central convex portion a of the first work W1 is inserted.
A vertical portion d extending upward from the bottom surface portion c, and a horizontal flange portion e extending radially outward from an upper edge of the vertical portion d, wherein the bottom surface portion c and the vertical portion d are first. Work W1
It is configured such that it is fastened by four screws 2, while being fitted in the orbiting convex portion b.

The screw fastening device 1 has a horizontal portion 3a extending in the horizontal direction and a vertical portion 3b extending vertically downward from the lower end surface of the horizontal portion 3a, and is positioned at a fixed position, for example, in three dimensions of XYZ. The apparatus main body 3 is attached and fixed to the controlled part of the industrial robot. Four bit rotation motors 4 are arranged at equal angular intervals in the vicinity of the peripheral portion on the horizontal portion 3a, and a servo motor 6 is fixedly mounted on the inner side thereof via a mounting frame 5. ing. A screw rod member 7 that is rotationally driven by the servo motor 6 penetrates the horizontal portion 3a and extends to the lower side thereof. on the other hand,
A rail 8 extending vertically is fixed to the vertical portion 3b.

Reference numeral 9 denotes an upper elevating member, which corresponds to the servo motor 6 and is disposed below the horizontal portion 3a and extends horizontally. The horizontal portion 9a extends vertically downward from the vertical portion 3b side of the horizontal portion 9a. Vertical portion 9b and reinforcing inclined portion 9 that connects them
with c and. The horizontal portion 9a is formed with a female screw portion 9d with which the screw rod member 7 is rotatably screwed, while the vertical portion 9a.
a slider 10 slidably sliding a rail 8 on b,
10 are provided. Therefore, by rotating the screw rod member 7 by the servo motor 6, the upper elevating member 9
Moves up and down along the rail 8 without rotating.

Reference numeral 11 is a pressing member, which is a cylindrical member 1 in the vertical direction.
2 is fixed. Then, the rod member 13 is provided so as to project downward from the horizontal portion 9a of the upper elevating member 9, and the rod member 13 is slidably fitted and inserted in the tubular member 12, whereby the pressing member 11 is attached to the upper elevating member 9. Is supported so that it can move up and down. In addition, the horizontal portion 9 of the upper lifting member 9
A coil spring 14 is interposed between a and the pressure member 11, and the coil spring 14 constantly urges the pressure member 11 downward. A pressure roller 16 is rotatably supported below the pressure member 11 via a bracket 15. Since the coil spring 14 is used, it is possible to reliably follow up even if the pressed side is deformed, and the fluctuating pressure force can be known in advance from the expected deformation amount and spring constant. The length of the coil spring 14 should be the servo mode.
It is adjusted by changing the vertical position of the upper elevating member 9 by the switch 6.

A lower elevating member 21 is arranged below the pressure member 11 so as to be vertically movable. The lower elevating member 21 has a horizontal portion 21a, a vertical portion 21b, and an inclined portion 21c connecting them, and sliders 22a and 22b slidably engaged with the rail 8 are fixedly provided on the vertical portion 21b. The floating member 23 is supported on the horizontal portion 21a so as to be finely movable in a horizontal plane, and the lower lifting member 21 is
Form part of the.

As shown in detail in FIGS. 2 and 3, the floating member 23 is provided with first and second pressers 24, ..., 25, ... At its lower end portion at a constant interval in the circumferential direction. And four bit members 26a, 26b, 26c, 2
6d (driver) and one centering rod 27
Are provided so as to penetrate therethrough. Further, among the holding members 24, ..., 25, ... Of the floating member 23, the bit members 26a, 26 are provided between the holding members 24 ,.
b, 26c, 26d and height sensors 35a, 35b, 35
c and 35d are alternately arranged, and height sensors 35a-3
5d is located at an intermediate point between the first pressers 24, ....

If the difference in height between the first and second pressers 24 and 25 is L1 and the difference between the bottom surface c of the second work W2 and the horizontal flange e is L2, then Difference ΔL (=
L1−L2) is slightly positive, and the first presser foot 24, ... Preloads on both sides of the opening into which the screws 2, ... are screwed, and the second work W2 is brought to the maximum value ΔL (= L1−L2). ) Only can be bent (see FIGS. 4 and 5).

The bit member 26a (26b, 26c,
26d) are linked to the rotary shaft 33 via the connecting rod 31 and the spline mechanism 32, respectively. The rotating shaft 33 is rotationally driven by the bit rotating motor 4. On the other hand, the centering rod 27 is provided with a load cell 34 (pressurizing sensor) in the middle thereof, and a pressurizing portion 27a with which the pressurizing roller 16 comes into contact is provided at the upper end portion. The lower end of the centering rod 27 engages with the concave portion a1 of the central convex portion a of the first work W1 to perform the centering operation of the floating member 23.

Reference numeral 41 is a control unit, which includes the load cell 34 and height sensors 35a, 35b, 35c and 35.
The servo motor 6 and the bit rotating motors 3 ...

With the above construction, when the screw is fastened, the upper elevating member 9 is lowered as shown by the chain line in FIG. 1, and the centering rod 27 is pressed by the pressure roller 16 supported by the pressure member 11. The pressure portion 27a is pushed down, and the lower lifting member 21 is also lowered.

At this time, the applied pressure is the coil spring 14
The fine adjustment of the length of the coil spring 14 is possible by using the servo motor 6.

At the same time, the lower end of the floating member 23 has the first work W of the centering rod 27.
The first work W1 is engaged with the concave portion a1 of the central convex portion a of FIG.
And the second work W2 is deflected by the pressing force. Since the pressing force is applied by the coil spring 14, even if the second work W2 to be pressed is deformed, it is possible to reliably follow it, and the expected deformation amount and the spring constant of the coil spring 14 can be used. The fluctuating pressure is known in advance.

The above load is a load through the coil spring 14, and this load is taken into the control unit 41 by the load cell 34. The difference between this load (current pressing force) and the target value is obtained, and the servo motor 6 is used to position the upper elevating member 9 in order to finely adjust the length of the coil spring 14 from the spring constant of the coil spring 14 so as to reach the target value. Control.

Further, the height sensors 35a, 35b, 35
The bit rotation motors 4, ... Are controlled (tightening control) until the respective deflections reach predetermined values by c and 35d. Abnormal pressurization can also be detected by the load cell 24.

In this way, the four screws are initially tightened simultaneously in the flexed state, and then the height sensors 35a, 35
Based on the output values from b, 35c, and 35d, the bit rotation motors 4, ... Are individually driven to perform tightening.

Further, since the coil spring 14 is used, it takes a considerable time to pressurize in consideration of the influence of inertia in the conventional one, but the time can be shortened. .

[0029]

According to the invention of claim 1, as described above, the force applied to the work is applied by the spring member through the pressing member, and the spring force of the spring member can be controlled. By setting the spring constant of No. 2 to an appropriate value, the change in the pressing force due to the deformation of the work can be kept within a certain range, and the pressing force can be adjusted with high accuracy.

According to the second aspect of the present invention, since the pressure sensor is used, the pressing force can be controlled more accurately.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a screw tightening device.

FIG. 2 is an enlarged cross-sectional view showing a relationship with a work.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an explanatory view showing the relationship of a presser foot.

FIG. 5 is an explanatory diagram of a second work.

[Explanation of symbols]

 W1 1st workpiece W2 2nd workpiece 1 Screw tightening device 3 Device body 9 Upper lifting member 11 Pressing member 14 Coil spring (Spring member) 21 Lower lifting member 26a ~ 26d Bit member 34 Load cell (Pressure sensor) 41 Control unit (control means)

Claims (2)

[Claims] 1. A screw tightening device in which a second work is placed on a first work having a screw hole, and the second work is screw-fastened to the first work by a bit member, the device body and the device. An upper elevating member that is vertically movable with respect to the apparatus main body and is vertically movable, a pressing member that is vertically movable with respect to the upper elevating member, the pressing member and the upper elevating member. A spring member interposed between the pressure member and a spring member for constantly urging the pressure member downward; and a spring member vertically movably supported by the pressure member below the pressure member and vertically moved by the pressure applied by the pressure member. And a lower elevating member that rotatably supports the bit member, and an adjusting unit that is linked to the upper elevating member and that adjusts the vertical position of the upper elevating member with respect to the apparatus main body. Screw tightening device. 2. A pressure sensor for detecting the pressure applied to the lower lifting member by the pressure member, and an adjusting means for adjusting the vertical position of the upper lifting member according to the output from the pressure sensor. The screw tightening device according to claim 1, further comprising a control means.