JPS6234660Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an automatic system that transmits information from a rotational drive source to the bit via a rotating shaft system, automatically supplies each screw from a screw supply device, and tightens the screw held in the catcher's jaw onto the workpiece. This invention relates to improvement of the rotating shaft system in a screw tightening machine.

Generally, a stationary automatic screw tightening machine is as shown in Fig. 1, and consists of a catch stand 3 on which a catcher B is fixed by an elevating power source 2 fixed on a column 1, and a support stand 5 on which a rotary drive source 4 is fixed. It is configured to move up and down integrally to a predetermined position. Further, a bit 6 is inserted into the catcher B so as to be able to slide back and forth and rotate freely, and which fits into a screw C supplied from a screw supply device (not shown). It is connected to a rotating shaft system A that is connected to the shaft 4a.

However, when using a commonly used automatic screw tightening machine to tighten a screw with a special head shape as shown in Fig. 5, that is, a screw C whose plane is elliptical and its front face is trapezoidal, as shown in Fig. 2. If the bit 6, which has a truncated conical fitting hole 6a with an elliptical plane that matches the head of the screw C, is simply attached to the bit shaft 7 of the conventional rotating shaft system A, the rotating shaft 4a will not be connected to the rotating shaft 4a during screw tightening work. Since the driven shaft 11 moves up and down against the drive shaft 10 connected via the universal joint 8 against the first spring 12, the screw C with such a head shape completely connects the workpiece 21. The current situation is that it cannot be tightened properly.

The work of tightening a screw to a workpiece with such a special head shape that requires enough pressure to prevent the fitting hole of the bit that fits into this head during tightening must be done manually by the worker, or The screws must be tightened using a portable screwdriver, and there is a problem in that it is very difficult to automate the assembly work using such screws. The present invention was devised focusing on this problem, and will be explained below based on FIGS. 3 to 5.

3 and 4, 8 is a universal joint connected to the rotating shaft 4a of the rotary drive source 4, and a connecting pin 13 is installed at the lower end of the universal joint 8 so as to be perpendicular to the central axis. A drive shaft 10 provided therein is connected. This drive shaft 10
A hollow cylindrical driven shaft 11 has a through hole 11b on the same center line in which the driven shaft 11 is slidably inserted back and forth.
The driven shaft 11 has two long grooves 11a formed along the center line and facing each other at right angles to the center line. The connecting pin 13 is connected to this long groove 11.
The drive shaft 10 and the driven shaft 11 can rotate together by engaging the connecting pin 13 and the long groove 11a, and the drive shaft 10 can move relative to the driven shaft 11. It is possible. Further, a support ring 14 is fixed to the driven shaft 11, and a connecting pin 13 is connected between the support ring 14 and the lower end of the universal joint 8 to repel each other when no load is applied. A first spring 12 is provided which is operative to engage. On the other hand, a second spring 15 is attached to the lower end of the universal joint 8 and the upper end of the driven shaft 11.
is locked, and this second spring 15 is arranged so as to be located around the drive shaft 10. Further, this second spring 15 has a free height shorter than the distance between the lower end of the universal joint 8 and the upper end of the driven shaft 11, and its upper end is in a free state. Therefore, the drive shaft 10
The second spring 15 is configured such that it operates only when the spring 15 is relatively moved to a predetermined position. Further, the second spring 15 is configured to have a smaller diameter than the first spring 12 and a larger spring constant than the first spring 12. The driven shaft 1
1 is connected to a universal joint 9 whose length is freely adjustable and has a bit shaft 7 fixed to its lower end, and the bit shaft 7 has a fitting that can fit into the shape of the head of the screw C shown in FIG. A bit 6 with a matching hole 6a is attached.

Further, the bit 6 and the bit shaft 7, which are fixed together, are attached to the catcher B attached to the catcher base 3.
A guide hole 16 bored in a nose 16 constituting the
A pair of screws are inserted loosely into the nose 16 so as to be able to reciprocate and rotate freely, and at the bottom of the nose 16 are a pair of screws facing each other so as to hold one of the supplied screws C, and whose tips are always urged to close. A seat 17 is provided. The screw holding portion of this jaw 17 is on the same center line as the bit 6. Further, the nose 16 is provided with a supply hole 18a through which the screw C from the screw supply device is guided through a supply hose (not shown), and a hose fitting 18 that is freely swingable about a support shaft 19.
is attached, and this hose fitting 18 is always urged by a third spring 20 so as to cross the guide hole 16a.

Next, the operation will be explained. As shown in FIG. 3, only one screw C is connected to the hose fitting 18 from the screw supply device
After the screw is supplied through the supply hole 18a and held in the screw holding part of the jaw 17, when a signal to start screw tightening is input, both the lifting power source 2 and the rotary drive source 4 operate, and the catcher B and the rotating shaft System A descends as one to a predetermined position. At this time, rotation axis system A
has started rotating. After catcher B stops descending at a predetermined position directly above the workpiece 21,
As the rotating shaft system A further descends while rotating, the bit 6 descends along the guide hole 16a, and the hose fitting 18 rotates counterclockwise as shown in FIG. The head of the screw C is fitted into the hole 6a, and the work of tightening the screw to the workpiece 21 is started. At this time, the first spring 12 of the rotating shaft system A
As a result, a thrust for screw tightening work is applied to the bit 6, so that the screw C is tightened to the workpiece 21. As the screw C is tightened to the workpiece 21, the driven shaft 11 is moved by the first spring by the amount of difference between the amount of descent of the rotating shaft system by the elevating power source 2 and the amount of advancement of the screw C into the workpiece 21. 1
2 and move backward relative to the drive shaft 10. As the driven shaft 11 retreats, the upper end of the second spring 15 placed on its upper end comes into contact with the lower end of the universal joint 8, and the second spring 15 begins to bend.

Further, when the elevating power source 2 is operated and the rotating shaft system is lowered, in addition to the elastic force corresponding to the amount of deflection of the first spring 12, the elastic force corresponding to the amount of deflection of the second spring 15 is applied to the driven shaft. 11 to the bit 6, and is applied to the screw C as a thrust force. Due to this thrust, the screw C can be completely tightened to the workpiece without the head of the screw C fitting into the fitting hole 6a of the bit 6 coming off.

As explained above, the present invention has a bit having a conical fitting hole, a drive shaft that receives rotation from a rotary drive source and rotates integrally with a universal joint, and a drive shaft that can be retracted relative to this drive shaft. 1st to
A second spring is placed around the drive shaft and on the upper end of the driven shaft, and the upper end of the second spring is connected to the lower end of the universal joint. Since it is configured to leave a predetermined distance between In addition to the elastic force of the spring, the elastic force due to the amount of deflection of the second spring can be used as the thrust of the screw, and as the screw enters the workpiece and the tightening torque increases, the bit will tighten the head of the screw. Even if the force in the direction of camming out from the screw increases, the thrust of the screw can be increased accordingly, and there is an advantage that the bit will never come out from the head of the screw. In addition, with this invention, a large thrust force is applied to the screw after the screw has entered the workpiece by a predetermined amount, so the increased thrust increases the frictional force between the male thread part and the female thread part, causing the bit to rotate. Since the time when the rotational drive source is subjected to a large load is only a short time, there are advantages such as there is no adverse effect on the rotational drive source.

[Brief explanation of the drawing]

Fig. 1 is a front view of an automatic screw tightening machine, Fig. 2 is an enlarged front view of main parts showing a conventional example, Fig. 3 is an enlarged front view of main parts showing the present invention, and Fig. 4 is an enlarged front view of main parts using the present invention. FIG. 5 is a perspective view of the screw to be tightened according to the present invention, and FIG. 6 is a bottom view of the screw shown in FIG. 5. A...Rotating shaft system, B...Catcher, C...
Screw, 1... Support, 2... Lifting power source, 3... Catching stand, 4... Rotating drive source, 4a... Rotating shaft, 5... Support stand, 6... Bit, 6a... Fitting hole , 7... Bit axis, 8, 9... Universal joint, 10... Drive shaft, 11... Driven shaft, 1
1a...Long groove, 11b...Through hole, 12...First
Spring, 13...Connection pin, 14...Support ring, 15...Second spring, 16...Nose, 16a...Guide hole, 17...Jyo, 1
8... Hose fitting, 18a... Supply hole, 19...
Support shaft, 20...Third spring, 21...Work.

Claims (1)

[Claims for Utility Model Registration] The rotation of the rotation shaft 4a of the rotary drive source 4 is controlled by the drive shaft 10.
The drive shaft 10 and the driven shaft 11 are coupled together so as to be rotatable and movable relative to each other, and a bit 6 is coupled to the driven shaft 11, so that as the rotary drive source 4 is lowered, the bit 6, the rotating shaft 4a is connected to a drive shaft 10 via a universal joint 8, and a first shaft is connected between the universal joint 8 and the driven shaft 11. Spring 1
2 is arranged to bias the driven shaft 11 in the direction of separating from the drive shaft 10 so that the driven shaft 11 can be moved back with respect to the drive shaft 10 together with the bit 6, while the second spring 15 is attached to the drive shaft 10 so that the diameter of the second spring 15 is smaller than the diameter of the first spring 12,
The lower end of this second spring 15 is connected to the driven shaft 1
1, the upper end of this second spring 15 is in a free state, and a predetermined distance is placed between the upper end of this second spring 15 and the lower end of the universal joint 8. A rotating shaft system characterized by the following configuration.