JPH0819923A - Automatic screw fastening device - Google Patents

Abstract

PURPOSE:To provide an automatic screw fastening device which does not mar a member to be fastened even when the head end of a screw part of a machine screw makes contact with the surface of the member to be fastened and which does not apply an impact load on a screw fastening member. CONSTITUTION:This device is furnished with a driver unit 14 to such a machine screw 10 and to carry out screw fastening, a detector 8 to detect a position of the driver unit 14 and an air control device 1 to control elevation of the driver unit 14 in accordance with a signal state from the detector 8. The air control device 1 consists of a cylinder 2 to actuate a piston by supply and exhaust of air, directional control valves 3, 4 to enable air exhaust from both ends of the cylinder 2 and a flow rate control valve 5 to control a flow rate of air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses the descending speed of the suction pipe sucking the screw until the screw tip of the screw enters the entrance of the screw insertion hole of the member to be tightened, and the screw insertion hole of the member to be tightened. At the same time as turning the bit after entering,
The present invention relates to an automatic screw tightening device that tightens screws by applying a pressing force required for screw tightening.

[0002]

2. Description of the Related Art The operation of screw tightening in a conventional automatic screw tightener equipped with an air cylinder will be described. By turning on the start switch of the automatic screw tightener,
The direction switching valve that switches the air flow direction switches,
Air is supplied to the upper end of the cylinder, and the lower end is exhausted. As a result, the piston in the cylinder descends, and the bit and suction pipe interlocked with the operation of this piston also descend. The bit rotates simultaneously with the descent, and the suction pipe sucks the screw held by the catcher, and at the same time, the tip of the bit fits into the head of the screw and the screw rotates. In this state, the tip of the suction pipe further lowers while pushing the tip side of the catcher open, the tip of the screw enters the screw insertion hole of the member to be tightened, the bit descends and the screw part of the screw is screwed into the female screw of the screw tightening member. Is screwed in to tighten the screws. Then, when the screw tightening is completed, the direction switching valve is switched to supply air to the lower end of the cylinder and exhaust the upper end. As a result, the piston in the cylinder rises, and the bit and suction pipe linked to the operation of this piston also rise.

[0003]

However, in the conventional automatic screw tightening machine, even if the screw is tilted and sucked by the suction pipe, or the screw is vertically sucked by the suction pipe, the member to be tightened is fastened. If the screw insertion hole of is misaligned with the axis of the suction pipe, the screw tip of the screw that descends while rotating does not enter the screw insertion hole of the tightened member, and the surface of the tightened member However, there was a problem in that it abuts against and damages the surface. Alternatively, the screw thread tip is once caught at the entrance of the screw insertion hole, and then it is inserted into the screw insertion hole so that it is difficult to insert, the impact load is applied to the screw tightening member, the screw tightening member is deformed, and the female screw of the screw tightening member There was also a fear that it would be crushed and that good screw tightening could not be achieved.

As a method of solving these problems, the exhaust rate of air from the lower end of the cylinder was controlled to suppress the descending speed of the adsorption pipe, but since air was supplied from the upper end of the cylinder, a sufficient effect was obtained. If the air displacement is too narrow, the descending speed required for screw tightening will not be obtained and good screw tightening will not be possible.

The present invention has been made in view of the above circumstances, and provides an automatic screw tightening device which is not damaged even if the tip of a screw portion of a screw comes into contact with the surface of a member to be tightened and is not subjected to impact load. The purpose is to do.

[0006]

In order to solve the above-mentioned problems, the present invention provides a driver unit which is arranged so as to be able to ascend and descend to suck a screw and tighten the screw, and a detector which detects the position of the driver unit. An air controller for controlling whether the driver unit is lifted or lower by determining whether the tip of the screw portion of the screw has entered the entrance of the screw insertion hole of the member to be tightened according to the signal state from the detector. However, this air control device has a cylinder that operates an internal piston by supplying and exhausting air to both ends, a direction switching valve that enables air exhaust from both ends of this cylinder, and a direction switching valve that switches the air flow direction. The flow control valve is provided between the switching valve and the cylinder and controls the flow rate of air.

[0007]

The piston in the cylinder is slowly moved down by the weight of the driver unit by switching the direction switching valve so that both ends of the cylinder are exhausted and the exhaust amount on the lower end side of the cylinder is suppressed. Then, it detects that the tip of the screw portion of the screw has entered the inlet of the screw insertion hole of the member to be tightened, switches the direction switching valve, and supplies air to the upper end of the cylinder. As a result, the driver unit descends at the speed required for screw tightening and tightens the screw.

[0008]

EXAMPLES The present invention will be described below with reference to the examples of FIGS. The air control device 1 includes a cylinder 2 that operates an internal piston by supplying or exhausting air to the upper and lower ends, a first directional switching valve 3 and a second directional switching valve 4 that switch the air flow direction, and The flow rate control valve 5 is provided between the one-way switching valve 3 and the second direction switching valve 4 and the cylinder 2 and controls the flow rate of air.

The main body unit 6 comprises a detector 8 for detecting the position of a suction pipe 7 which will be described later, a catcher 11 for holding a screw 10 supplied from a screw supply unit 9, and a mounting plate 12 to which these are attached. The detector 8 is composed of a photosensor fixed to the mounting plate 12, and detects the height of the suction pipe 7 by light shielding by passing through the light shielding plate 13 fixed to the suction pipe 7.

The driver unit 14 includes a suction pipe 7 for sucking the screw 10 held by the catcher 11, a driver 15 having a built-in motor, a bit 16 attached to the lower end of the driver 15 and screwed by rotation. The holder 17 is mounted so that the holder 17 can be moved up and down in conjunction with the operation of the piston in the cylinder 2 with the shaft 18 fixed to the mounting plate 12 as a guide.

Next, the operation of the automatic screw tightening device according to the present embodiment when the screw tightening work is performed will be described. By turning on the start switch of the automatic screw tightening device, the lower end of the cylinder 2 until now is shown in FIG. The first directional control valve 3 that has been supplied with air and has been exhausted at the upper end is switched, and as shown in FIG. 4, the lower end of the cylinder 2 is exhausted and the air is supplied at the upper end. However, since the second directional control valve 4 is exhaustly connected to the upper end of the cylinder 2, the air from the first directional control valve 3 stops at the second directional control valve 4 and is not supplied to the upper end of the cylinder 2. Therefore, both ends of the cylinder 2 are in an exhaust state, and the piston in the cylinder 2 descends due to the weight of the driver unit 14. At this time, the exhaust amount on the lower end side of the cylinder 2 is suppressed by the flow control valve 5 on the lower end side, and the driver unit 14 slowly descends.

The screw held by the catcher 11
The tip side of the suction pipe 7 enters the head portion 19 of the screw 10, and the screw 10 is sucked. And by lowering the driver unit 14,
The tip 20 of the suction pipe 7 hits the catcher 11 and pushes the tip of the catcher 11 open. When it further descends and the tip of the screw portion of the screw 10 enters the entrance of the screw insertion hole 22 of the member 21 to be tightened, the detector 8 passes the light shield plate 13 to move the suction pipe 7, that is, the position of the driver unit 14 in the height direction. It detects that it is in the normal position and issues a position OK signal.
As a result, the second directional control valve 4 is switched, and as shown in FIG. 5, the air previously stopped at the second directional control valve 4 is sent to the upper end of the cylinder 2. As a result, air pressure is applied to the upper end of the cylinder 2, the bit 16 rotates, and at the same time, the driver unit 14 descends at the speed required for screw tightening, and the screw portion of the screw 10 is screwed into the screw tightening member 23 to tighten the screw. To do.

The height detection by the passage of the light shielding plate 13 is performed by determining the height movement amount of the suction pipe 7 from the number of the comb teeth of the comb tooth-shaped light shielding plate 13 as shown in FIG. Whether the height is normal or abnormal is determined by the number of passages within the descent time.

When the screw tightening is completed, the rotation of the bit 16 is stopped, and as shown in FIG. 3, the first directional control valve 3 and the second directional control valve 4 are simultaneously switched to supply air to the lower end of the cylinder 2. The upper end is exhaust. Cylinder 2
The piston inside moves up, and the driver unit 14, which is linked to the operation of the piston, also moves up. Then, the screw 10 is sent from the screw supply unit 9 into the catcher 11 and held therein, and the next screw tightening operation starts.

Next, the operation when the screw insertion hole 22 of the tightened member 21 is displaced with respect to the axis of the suction pipe 7 and the tip of the screw portion of the screw 10 comes into contact with the surface of the tightened member 21. The suction pipe 7 sucking the screw 10 descends, and the tip of the screw portion of the screw 10 comes into contact with the surface of the tightened member 21. At this time, since the suction pipe 7, that is, the driver unit 14 is stopped at a high position, the detector 8 emits a signal at the position NG due to the insufficient number of comb teeth passing through the light shield plate 13. Then, the first directional control valve 3 is switched, air is supplied to the lower end of the cylinder 2, the piston moves up, and the driver unit 14 interlocked with the operation of the piston also moves up.
Then, the screw tightening operation starts again.

Although two directional control valves are used in this embodiment, both ends of the cylinder may perform the exhausting function with only one directional control valve. Further, the photo sensor may be provided on the driver unit side, and the light shielding plate may be provided on the main body unit side.If the position in the height direction of the driver unit can be detected, the detector is not limited to the photo sensor, and other methods,
Various attachments are possible.

As described above, in this embodiment, the driver unit is slowly lowered by its own weight by setting both ends of the cylinder in the exhaust state. Then, after detecting that the screw tip of the screw sucked by the suction pipe has entered the screw insertion hole of the tightened member, rotate the bit and apply the pressing force necessary for screw tightening to the screwdriver unit. Tighten. Therefore, even when the tip of the screw portion of the screw comes into contact with the surface of the member to be tightened, the surface of the member to be tightened is not damaged. Also, no impact load is applied to the screw fastening member.

[0018]

According to the present invention, a driver unit is provided which is capable of ascending and descending to suck a screw and tighten the screw, a detector for detecting the position of the driver unit, and a signal state from the detector. An air control device is provided for controlling whether the tip of the screw portion of the screw has entered the entrance of the screw insertion hole of the member to be tightened to control the lifting and lowering of the driver unit. A cylinder that operates an internal piston by supplying and exhausting it, and a direction switching valve that enables air to be exhausted from both ends of this cylinder and switches the air flow direction.
The driver unit slowly descends by its own weight because it consists of a flow rate control valve that controls the flow rate of air provided between this direction switching valve and the cylinder, and the tip of the screw part of the screw inserts the screw of the tightened member. Even if the member does not enter the hole and comes into contact with the surface of the member to be tightened, the surface is not damaged. Further, even if the tip of the screw portion of the screw is once caught at the inlet of the screw insertion hole of the member to be tightened and then enters the screw insertion hole, no impact load is applied to the screw tightening member, and good screw tightening is possible.

[Brief description of drawings]

FIG. 1 is an overall view showing an automatic screw tightening device according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a state in which a suction pipe sucking screws of the embodiment is lowered.

FIG. 3 is an operation explanatory view of the cylinder of the embodiment, in which the piston is in a raised state.

FIG. 4 is an operation explanatory view of the cylinder of the embodiment, in which the piston is in the middle of lowering.

FIG. 5 is an operation explanatory view of the cylinder of the embodiment, in which the piston is in a lowered state.

[Explanation of symbols]

 1 Air control device 2 Cylinder 3 1st directional switching valve 4 2nd directional switching valve 5 Flow control valve 7 Adsorption pipe 8 Detector 10 Screw 14 Driver unit 21 Fastened member 22 Screw insertion hole

Claims (1)

[Claims] 1. A driver unit, which is arranged so as to be able to move up and down, for sucking a screw and tightening the screw, a detector for detecting the position of the driver unit, and a screw unit for the screw according to a signal state from the detector. It is equipped with an air control device that controls whether the tip of the screw has entered the entrance of the screw insertion hole of the member to be tightened and controls the elevation of the driver unit. This air control device supplies and exhausts air to both ends. By operating the internal piston, a directional switching valve that allows air to be exhausted from both ends of the cylinder, and switches the flow direction of the air, and a directional switching valve that is provided between the directional switching valve and the cylinder. An automatic screw tightening device comprising a flow rate control valve for controlling the flow rate of