JPS6013559Y2 - Workpiece detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device that is attached to a workpiece holding member and used to detect whether or not a workpiece is held in a predetermined position.

The work holding member is, for example, a finger of a work transfer device used in an automated press machine such as a transfer press.

This type of workpiece transfer device is constructed by attaching fingers for clamping (holding) the workpiece to a feed bar that can perform a composite motion that combines reciprocating motion in two directions: the workpiece transfer direction and the direction perpendicular to this direction. It is normal to do so.

The workpiece is clamped and transferred intermittently as it is moved according to a predetermined cycle.

Such a work transfer device is usually equipped with a device for detecting whether the work is in the correct position.

This is because if the workpiece is shifted from the normal clamping position, or if the machine operates even though it is not clamped, there is a risk of defective products or damage to the press mold due to blank punching. .

As the above-mentioned detection device, a type in which a limit switch fixed near the root of the finger is operated by a rod-shaped contact movable in the axial direction near the tip of the finger is widely known. Ta.

However, since this contact has conventionally been made of metal, there has been a problem in that its inertia is large and sliding properties are reduced.

In order to solve this problem, the present applicant has developed a detection device in which most of the contacts are made of synthetic resin and are fitted into a guide hole of a base body equipped with an installation chamber for a limit switch.
An application was filed for utility model registration under Utility Model Application No. 1983-71020.

In this way, the contact becomes lightweight, so its inertia becomes small, and the friction coefficient between it and the base guide hole is reduced, so that the sliding resistance becomes small.

Furthermore, there is no fear of rust, the need for lubrication is reduced, the adhesion of dust, etc. is prevented, and smooth sliding is achieved.

As a result, the urging force of the spring that urges the contact forward can be small, and the contact can be operated with a small force.

If the contact of each limit switch is made lighter, the amount of deflection of a feed bar with a plurality of limit switches installed becomes smaller.

If a detection device including this contactor was used, the various advantages described above were certainly enjoyed, but as the device was continued to be used, some devices began to malfunction.

As a result of the investigation, it was determined that the cause of this problem was the contactor's rotation prevention means.

In other words, since there are cases where it is unavoidable that a rotational force is applied to the contact during detection, generally, a contact with a circular outer shape has a flat surface formed in a part of the contact that is brought into contact with the pin body. It was fitted into a guide hole in the base body, with rotation prevented by a pin body.

However, when the external shape of the pin body is circular, the flat surface of the contact and the pin body come into linear contact, increasing the surface pressure on the contact surface, increasing the sliding resistance, and causing the contact Multiple depressions were sometimes formed on the flat surface.

This problem has been eliminated to a considerable extent by the workpiece detection device for which the present applicant previously applied for utility model registration on December 22, 1932.

This is because the surface pressure on the contact surface was reduced because the pin body was brought into surface contact with the flat surface of the cam body, which had a flat surface formed on a part of the pin body, and this fact was confirmed by the experiment described above. As stated in the specification of the application.

However, while considering whether it was possible to further reduce the sliding resistance, we came up with the idea of using the conventional concept and making the contact into a prismatic shape.

As a result of experiments, it has been confirmed that by doing so, the sliding resistance is much smaller than when using the pin body having the flat surface.

The present invention was developed based on this knowledge, and in order to minimize the sliding resistance of the contact, the cam body, which is the main body of the contact, is made into a prismatic shape, and the guide hole of the base is made into a prismatic shape. The cross-sectional shape is a corresponding shape (rectangle).

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on FIGS.

In Fig. 1, B indicates a feed bar that can be moved forward, backward, left, and right, and F indicates feed bar B.
There are fingers fixed on the top as work holding members.

On the finger F, a base body 1 made of synthetic resin such as nylon 6 is attached to bolts 4 (first
(see figure).

A nearly rectangular limit switch installation chamber 6 is formed in the base body 1, leaving a box-shaped outer wall 5, and a cam-opening inner hole 68 (dead-end hole) with a rectangular cross section is formed in the guide part 7. The notches 9 communicate with each other.

A rond-shaped contact 15 is fitted into the guide hole 8 so as to be able to come into contact with the workpiece W.

This contact includes a square prism-shaped cam body 11 obtained by molding a synthetic resin such as nylon 6, and a stylus 12 inserted through the cam body 11.
I warn you from this.

A cam surface 13 having an isosceles trapezoidal cross section is formed on one side of the cam body 11 near the rear end (the right end in FIG. 2).
It is urged forward by a compression spring 16 disposed between the large diameter hole 14 and the rear wall 15 of the guide hole.

A flat surface 18 of a predetermined length is formed in front of the cam surface 13, and a cylindrical synthetic resin pin 17 driven into the outer wall 5 engages with this flat surface. Extraction is prevented.

The stylus 12 extends through the cam body 11 and the rear wall 15, and its tip is bent at a right angle to form a bent portion 19.

Relative rotation and movement of the stylus 12 with respect to the cam body 11 is prevented by a metal ring 22 fitted into the small diameter portion 21 and a small screw 23 screwed into the metal ring 22 .

The machine screw 23 is screwed into a female thread 26 having a metal ring 22 shape, passes through a through hole 27 drilled in the small diameter portion 21, contacts the stylus 12, and fixes the stylus 12 to the cam body 11. There is.

Further, a limit switch (LS) 28 for controlling the operation of the feed bar B is fixedly installed in the installation chamber 6.

The actuator 29 of Ls28' extends in the direction of the notch 9, and a roller 31 pivotally attached to the tip thereof is engaged with the cam surface 13.

Further, the cord 32 is taken out from a groove 33 formed in the outer wall 5.

A cover 34 (see FIG. 2) is placed on the outer wall 5.

(removed in Figure 1) is attached.

In the detection device configured as above, the feed bar B
At the same time, when the finger F moves forward and clamps the workpiece W at a normal position, the bent portion 19 of the stylus contacts the workpiece W, and the contactor 15 is moved back against the elastic force of the spring 16.

In this case, the cam body 11, which occupies most of the contactor 15, is made of lightweight synthetic resin, and is inserted into the guide hole 8 of the base body 1, which is also made of synthetic resin, so that inertia and sliding resistance are reduced. It is small and retreats easily.

As a result, the roller 31 of the actuator 29 moves onto the cam surface 1.
3, the LS 28 is activated, a detection signal is output, and the feed bar B moves to the right or left to transfer the work W and process it with the press machine.

On the other hand, even if the finger F reaches the above-mentioned normal position, if the stylus 12 does not contact the workpiece W, L328 will not operate and no detection signal will be output, so the operation of the press machine will be stopped, and this fact An alarm will be issued to notify the operator.

In order to examine the slidability of the contactor 15 when a torsional force is applied to the detection device of the above embodiment, an experiment was conducted using the device shown in FIG. 4.

In this experiment, a weight W of 1 kg was suspended from the bent part 19 of the stylus 12, which was placed horizontally, and the distance 1 from the bending point A was set to H.
The force required to slide the contactor 15 was measured using instrument B while changing the force by 1b+m.

The result is shown in FIG. 5 by bending line E.

The curves C and D in the figure indicate similar experiments using a detection device with a cylindrical cam body and a sliding contact whose rotation is prevented by a locking pin. The results are shown below.

However, the shape and material of the pin bodies are different; the former C uses a round bar-shaped pin made of metal, while the latter uses a flat pin made of synthetic resin.

As mentioned in the application above, by using a flat pin made of synthetic resin, the sliding resistance was lower than when using a round bar-shaped pin made of metal. It is clearly shown that when the contactor 15 is used, the sliding resistance is much smaller than when the flat pin body made of synthetic resin is used.

This is thought to be because the cam body 11 forming the main body of the contact 15 is made into a square column shape, so that the contact area with the guide hole 8 is greatly improved, and the surface pressure on the contact surface is significantly reduced.

Note that the specific shape of the cam body 11, the position of the cam surface 13,
The pull-out prevention means and the like may be modified and improved as appropriate in relation to the guide hole 8 and the like.

In addition, in order to more reliably prevent the stylus 12 from rotating relative to the cam body 11, a metal ring 2 is attached as described above.
It is desirable to screw the machine screw 23 into the cam body 11, but if the twisting force is relatively small, the machine screw 23 may be screwed into a metal member embedded in the cam body 11.

As detailed above, in the work detection device according to the present invention, the cam body, which is the main body of the contact, is made of synthetic resin and has a prismatic shape, so that it enjoys the above-mentioned advantages of the cam body made of synthetic resin. However, even when the contact is used in such a way that a torsional force is applied to the contact, the contact can easily slide and this state can be maintained for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention (however, the cover 3
4 has been removed), Fig. 2 is a plan view (partially broken), Fig. 3 is a sectional view taken along ■-■ in Fig. 2, and Fig. 4 is a diagram of the experiment conducted using the above example. The explanatory diagram, FIG. 5, is a graph showing the results. 1...Base body, 6...Installation room, 8...
...Guide hole, 11...Cam body, 12...
...Stylus, 13...Cam surface, 16...
Compression spring, 17... Pin, 18... Flat surface, 19... Bent part, 22... Metal ring, 23... Small Screw, 26... Female threaded hole, 27... Circular hole, B... Feed bar Fsse*e* finger, W... Work.

Claims (1)

[Scope of Claim for Utility Model Registration] A device that is attached to a workpiece holding member such as a workpiece transfer device and detects whether or not the workpiece holding member has properly held the workpiece, comprising a limit switch installation chamber and a cam with a rectangular cross section. a synthetic resin base body having a body guide hole; and a synthetic resin base body having an overall prismatic shape, having a cam surface on the negative side, and being biased in one direction and fitted into the cam body guide hole. a cam body; a stylus that is inserted through the cam body and contacts the workpiece at its tip; and a limit switch installed in the limit switch installation chamber so that an actuator engages with the cam surface. A workpiece detection device characterized by: