JPS59227338A - Device for absorbing level difference in nut tightening - Google Patents

Abstract

PURPOSE:To enable an automatic nut tightening machine with retightening function, to tighten a nut even the tightening face of the nut is different, by providing the machine with a guide pin movable along the axis of a box bit and with a detector for detecting a relative position between the guide pin and the box bit. CONSTITUTION:A box bit 7 is lowered so that a guide pin 14 enters into the threaded portion of a nut T held by a catcher 10, and the nut N comes to be held on the box bit by vacuum suction. The box bit 7 is rotated clockwise by means of a bit holder 15, so that the guide pin 14 is applied on a screw S and withdrawn inside the box bit 7, while the nut N is tightened onto the screw S. The withdrawal of the guide pin 14 causes a detecting pin 17 abutted on the guide pin 14 to retreat, so that a detecting ring connected to the detecting pin comes close to a deector 21. When the guide pin 17 is withdrawn by a distance l, the detector 21 detects the detecting ring 18. If such a distance l is a given value, the nut is tightened with set torque.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is an automatic nut tightening machine equipped with a re-fastening function. The present invention relates to a level difference absorbing device.

Conventional Structure and Problems In the automatic NAND tightening machine 1 as shown in Fig. 1, in order to increase the quality of nut tightening, a re-tightening method as shown in Fig. 2 is used when a nut is tightened incorrectly. It's blown.

First, the distance H between the door 3 fixed to the driver holder 2 and the roller 6 of the microswitch 5, which is attached to the slide shaft 4 that guides the driver 2 when the driver 2 moves up and down, so that the position can be adjusted, and the box Distance I from bit 7 to the tip of screw S! Adjust the position of the microswitch 5 so that the distance H up to (3 to 4 screw pitches) is the same. Thereafter, the box bit 7 is lowered by a lifting device 8 connected to the driver holder 2.

At the same time as the descent starts, the box bit 7 is rotated clockwise by the driver 9, which is a rotational drive source. (When the screw S is a right-handed screw, and if it is a left-handed screw, it rotates counterclockwise.Hereinafter, it will be explained as a right-handed screw.The screwdriver 9
The final tightening is performed with torque T2, which is lower than torque T1. The nut N is captured by the box bit 7 and tightened.

If the set torque T2 is not reached during tightening during the distance g, the microswitch 6 is activated and the final tightening is automatically switched to the torque T1 to complete the tightening. When the screw S is tightened obliquely to the screw S and the set torque T2 is reached, the driver 9 rotates counterclockwise for a certain period of time, and then rotates clockwise again at the set torque T2 for re-tightening.

If the set torque T2 is not reached during tightening over the distance l, the microswitch 5 is activated, and the final tightening is automatically switched to the torque T1 to complete the corrective tightening. As is clear from the above explanation, the microswitch for determining the quality of nut tightening and switching the torque is fixed at a position uniquely determined by the distance between the box bit and the screw, so the height of the screw is For different workpieces, the microswitch position must be readjusted. In addition, it is not possible to use this method in terms of productivity when nuts are alternately tightened on works having different screw heights.

Purpose of the Invention The present invention has been devised in view of the above problems, and has a re-fastening function and can arbitrarily follow the tightening of nuts for workpieces with different surface heights. The object of the present invention is to provide a level difference absorbing device that performs the following steps.

Constituent structure of the invention A guide bin is provided to detect the screw position by coming into contact with the tip of the screw, and the screwed-in position of the nut is replaced by the relative positional relationship between the box bit and the guide bin, and is detected by a proximity switch via the detection means. Therefore, the detection of the nut screwing position required for the re-fastening function can be performed arbitrarily, even for workpieces with different heights of the nut tightening surface, which has the unique effect of tightening nuts with a high rate of non-defective products. Demonstrate.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In Figures 3 to 6, 2 is a driver holder, 4 is a slide shaft, 7 is a box bit, 8 is a lifting device,
Reference numeral 9 denotes a driver, which has the same configuration as that shown in FIG. 2 (prior art example).

Reference numeral 10 denotes a catcher that horizontally supports the oak (oak) N. The catcher 10 is supported by a catcher bin 11 so as to be able to swing around the catcher bin 11, and is pulled upward by a spring 12. It is in contact with the bolt 13.

14 is the center of the box bit 7.
It is supported in a direction that allows it to move in the axial direction, and the part from the tip that is approximately three times the thickness of the N is cylindrical with a diameter slightly smaller than the root diameter of the threaded part of the N. It is a guide bin. Reference numeral 15 denotes a focus holder which is connected to a dry bar 9, which is a rotational drive source, by a joint 16, and has a box bit 7 screwed into the other end, making it partially hollow. 1
A detection bin 7 is located in the hollow part of the bit holder 16, is held movable in the axial direction of the bit holder 15, and has one end in contact with the guide bin 14. Reference numeral 18 denotes a detection ring which has a hollow shape, is arranged so that the bit holder 15 can be inserted into the hollow part, and is connected to the detection pin 17 by a pin 19.

Reference numeral 20 designates an outer pipe which has a hollow shape, has a detection ring 18 built therein, and is fixed to the driver holder 2. A detector (proximity switch) 21 is attached to the outer pipe 20 so as to be adjustable in position in the axial direction, and detects movement of the detection ring 18.

The operation of the NAND tightening level difference absorbing device configured as above will be explained.

First, as shown in FIG. 3, when the box bit 7 is lowered, the guide pin 14 enters the threaded part of the nut N held in the catcher 10, and the center of the nut N is aligned with the axis of the box bit 7. Fixed. Further, the oak) N is held in the box bit 7 by vacuum suction. Further, when the lowering starts, the driver 9 rotates clockwise with a torque T2 lower than the final tightening torque T1, and the box bit 7 rotates clockwise via the bit holder 16.

Next, as shown in FIG. 4, the guide pin 14 comes into contact with the screw S and retreats into the box bit 7, and the nut N is tightened onto the screw S. As the guide bin 14 retreats, the detection bin 17 that is in contact with the guide bin 14 retreats, and the detection pin 17
The detection ring 18 connected to the detector approaches the detector 21 (.

Thereafter, as shown in FIG. 6, the nut N is tightened several times, the guide bin 17 is moved back a distance l, the detector 21 detects the detection ring 18, and the screwdriver 9 changes the set torque T2 to the final tightening torque. Switching to T2, tightening is completed as shown in FIG.

However, when tightening between distance l, N is the screw S.
If the box bit 7 is tightened obliquely, the box bit 7 is prevented from moving forward, so the guide bin 14 does not move back and the detector 21Fi does not detect the detection ring 18. When the set torque T2 is reached in this state, the driver 9 rotates counterclockwise for a certain period of time, and then rotates clockwise again at the set torque T2 for re-fastening. If the set torque T2 is not reached during tightening over the distance l, the detector 21 detects the detection ring 18, and the driver 9 switches the final tightening to the torque T1 to complete the corrective tightening.

Effects of the Invention As described above, since the present invention detects the movement of the guide pin after it comes into contact with the screw, the tightening of the screw can be arbitrarily followed even for workpieces with different surface heights. , it is possible to tighten nuts with a high rate of non-defective products, and the effect is great.

[Brief explanation of the drawing]

Fig. 1 is an overall side view of an automatic nut tightening machine, Fig. 2 is a partial side sectional view of a conventional automatic nut tightening machine, and Fig. 3 is a partial side sectional view of an automatic nut tightening machine according to an embodiment of the present invention. Figure 4 is a partial side sectional view showing the state when the nut is tightened to the screw, Figure 5 is a partial side sectional view showing the state when the torque is switched, and Figure 6 is the tightening state. It is a partial side sectional view which shows the state at the time of completion. 7...Box bit, 9...Driver, 10...Catcher-114...
・Guide bin, 16...Bit holder, 17
...Detection tip, 18...Detection ring, 2
1...Detector. Name of agent: Patent attorney Toshio Nakao (1st person)
figure

Claims (1)

[Claims] A catcher that holds the nut horizontally, a box bit that captures the nut by vacuum suction and tightens it to the screw, a guide pin that is held at the center of the box bit so that it can move in the axial direction of the box bit, and a rotating a driver that is a driving source; a bit holder that is connected to the driver by a coupling and whose other end is connected to a box bit and is partially hollow; a detector that detects the relative position of the guide pin and the box bit; A nut tightening level difference absorbing device comprising: detecting means, at least a portion of which is located within a hollow portion of a bit holder, and detecting means for transmitting the position of the guide pin to a detector.