JP2547593B2 - How to supply project nuts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for supplying a projection nut having a welding projection to a spot welding machine,
In particular, the feature is that nuts are accurately supplied to the guide pin of the fixed electrode.

(B) Conventional technology As a conventional technology, Japanese Utility Model Publication No. 53-26423 (B23K11 /
10), the contents of which are shown in FIGS. 8 and 9. Referring to the figure, a protrusion 3 having an arc portion 2 is provided at the tip of the supply rod 1, the protrusion 3 is inserted into the screw hole 5 of the nut 4, and this inserted state is maintained by the attraction force of the electromagnet 6. , Supply rod 1
When the nut 4 advances and the lower side of the front surface of the nut 4 comes into contact with the guide pin 8 of the fixed electrode 7, the nut 4 rotates counterclockwise from that state, and the nut 4 and the screw hole as shown by the two-dot chain line in FIG. 5 and 5 fit together. In addition, 9 is a steel plate component mounted on the fixed electrode 7.

(C) Problems to be Solved by the Invention In the above-mentioned conventional technology, the bottom of the front surface of the nut 4 is basically abutted against the guide pin 8. Therefore, the contact point of the nut 4 with the guide pin 8 is accurate. And the stop position of the supply rod 1 must be set as well. If the contact point is slightly deviated in the vertical or horizontal direction, the turning locus of the nut 4 is displaced from the guide pin 8, and eventually the screw hole 5
The guide pin 8 does not enter the inside, which is a so-called misfeed. Furthermore, the above-mentioned supply rod 1
If the stop position of the nut 4 is too advanced, the lower front surface of the nut 4 hits the guide pin 8 strongly, so that the nut 4 pivots excessively and jumps over the guide pin 8. . Further, if the stop position is slightly before the guide pin 8, contact between the nut 4 and the guide pin 8 cannot be obtained, and the nut does not rotate.
Or it will fall just before the guide pin 8. The protrusion 3 having such an arc portion 2 has a problem that the nut 4 easily comes off if some external force acts on the nut 4 during the forward movement of the supply rod 1.

(D) Means for Solving the Problem and Its Action The present invention is provided to solve the above-mentioned problem, and a projection nut is attached to the tip of the supply rod from below to be in close contact with the projection nut. The projection rod that holds the projection rod is held in a state where the projection rod is magnetically attracted and held at the tip of the supply rod, and the relative position between the tip corner of the projection and the projection nut is set. Of the projection nut immediately before the guide pin, and stop the supply rod in a state where the projection nut does not come into contact with either the steel plate parts or the guide pin. With its own weight, it falls down around the corner of the tip of the protrusion, then the projection The projection nut is made to match the guide pin of the fixed electrode.The projection nut is held stably from below with the projecting piece in close contact, and the tip corner of the projecting piece and the projection nut The position of the projection nut should be determined in advance by deciding the position, and the magnetic attraction force should be eliminated almost at the same time that the feed rod stops advancing without the projection nut contacting any steel plate parts or guide pins. Thus, the projection nut is inverted about the tip corner portion of the projecting piece to achieve reliable nut supply.

(E) Practical Example The example shown in FIGS. 1 to 7 will be described. First,
Project nut (hereinafter simply referred to as nut)
Reference numeral 10 is a square shape as shown in FIG. 3, and projections 11 for welding are provided at the four corners.

Referring to FIG. 1, FIG. 2, FIG. 4, FIG. 6, and FIG. 7, a plate-shaped projection piece 13 for holding the nut 10 from below is provided at the tip of the supply rod 12. ing.
In order to hold the nut 10 at the tip of the supply rod 12 by the attractive magnetic force, the supply rod 12 is a hollow shaft as shown in the drawing, and the inner rod 14 is slidably inserted therein. A magnet (permanent magnet) 15 is fixed (adhered) to the tip of the rod 14, and
The lower end surfaces of 15 and the supply rod 12 coincide with each other and are flush with each other as shown in the drawing. The supply rod 12 strokes obliquely downward or in a substantially horizontal direction. Counterpart steel plate parts 16
Is placed on the fixed electrode 17, and the fixed electrode is placed in the hole of the steel plate component 16.
The 17 guide pins 18 penetrate. Reference numeral 19 indicates a screw hole of the nut 10, and the movable electrode paired with the fixed electrode 17 is not shown.

FIG. 1 shows that the supply rod 12 is stopped immediately before the guide pin 18, that is, the target position, and the nut 10 is supplied to the supply rod 12.
As shown in the figure, the protruding piece 13 and the nut 10 are in close contact with each other and are already held at the tips of the nut 10 and the protruding piece 13.
The relative position with respect to 20 is determined, and at this time, the relative position is set in advance so that the screw hole 19 and the guide pin 18 can be matched well by the later-described nut overturning. It is in a state of not contacting either 16 or the guide pin 18. First
When the inner rod 14 is retracted from the state shown in the figure and the magnet 15 is separated from the nut 10 as shown in FIG. 2, the attractive magnetic force for the nut 10 disappears. It rotates counterclockwise around 20 and the screw hole 19 is aligned with the guide pin 18 to complete nut feeding as shown by the two-dot chain line in FIG.

FIG. 6 is a vertical cross-sectional view showing the entire apparatus for carrying out the method of the present invention. In the state in which the supply rod 12 having the structure as shown in FIGS. An operating cylinder (air cylinder) 22 is accommodated in the upper end of the outer cylinder 21, and a shutter 23 for guiding the nut 10 is welded to the lower end of the outer cylinder 21. A guide plate 24 is fixed to the end of the shutter 23, and a magnet (permanent magnet) 25 embedded therein guides the nut 10 by suction.

A mechanism for forcibly retracting the magnet 15 (inner rod 14) as shown in FIG. 2 will be explained with reference to FIG. 7. A regulating pin 26 fixed to the inner rod 14 penetrates an elongated hole 27 opened in the stroke direction of the supply rod 12. Then, it projects outside the supply rod. A drive device 28 is fixed to the outside of the outer cylinder 21. Although an electromagnetic solenoid or the like can be used as the drive device 28, an air cylinder 29 is illustrated here, and an engaging piece 31 fixed to the tip of the piston rod 30 has a long hole 32 in the stroke direction opened in the outer cylinder 21. And is looking into the outer cylinder, and that part is made to face so that it can abut against the restriction pin 26. The compression coil spring 33 is inserted between the inner rod 14 and the supply rod 12, and its resilience is received by the restriction pin being pressed against the lower portion of the long hole 27. Further, 34 is the above-mentioned working cylinder 22.
It is connected to the supply rod 12 at the piston rod of.

From the state shown in FIG. 7, the supply rod 12 is advanced by the piston rod 34, and the nut is placed just before the target point as shown in FIG.
When the stop 10 stops in a state where it does not contact either the steel plate component 16 or the guide pin 18, the regulation pin 26 also stops immediately before the engaging piece 31. Then, when the engagement piece 31 is pulled up by the air cylinder 29, the inner rod 14 moves to the second position via the restriction pin 26.
It is forced to retreat as shown in the figure.

The timing at which the attracting magnetic force to the nut 10 is extinguished is almost the same as the stop of the supply rod 12, and the best time is immediately after the stop of the supply rod 12.

In the above embodiment, the nut is attracted and held by using the permanent magnet, but as another method, the tip of the supply rod is magnetized by using the electromagnet as shown in FIG. Should be demagnetized. The fifth
In the figure, wall members 35 are provided on both sides of the projecting piece 13 to form a substantially U-shaped frame shape to improve the holding property of the nut 10.

(F) Effect According to the present invention, the advance of the supply rod is stopped so that the nut is in front of the guide pin and is in a state of not contacting any of the steel plate parts and the guide pin.
It is possible to completely avoid the problems caused by the contact as in the above-mentioned prior art. The nut is held so as to be supported from below by the projecting piece and is suction-held by magnetic force, so that the projecting piece does not fall accidentally even while the supply rod is moving forward. Due to the close contact with the nut, the relative position between the tip corner portion, which is the fall center point, and the nut is accurately determined. Therefore, if only the stop position of the supply rod is accurately set, the fall at the correct position can be obtained with the fall center point as the base point.

In other words, since the nut turns around the tip angle of the protruding piece and falls down toward the guide pin by its own weight, the nut position of the nut is determined as the relative position between the tip corner portion and the nut is determined. The falling trajectory can be made constant at all times, and the accuracy of supplying the guide pin is significantly improved.

Since the nut does not come into contact with the steel plate parts or the guide pins, and moreover falls due to its own weight around the tip corner portion of the projecting piece, it is not necessary to strictly adjust the contact position as in the prior art. That is, the center of the relative fall of the nut with respect to the guide pin is determined by the minimum number of elements, which is the stop position of the supply rod, so the rest is the relationship between the inner diameter of the screw hole of the nut and the thickness of the guide pin and the guide pin. It suffices to adjust the relationship with the length of, so that the difficult work of completing many adjustment items as in the conventional example can be omitted.

Then, the attractive magnetic force for the nut is to be eliminated after the supply rod stops immediately before the target location, so the tip corner portion of the protrusion, which is the center of the nut overturn, is required to have a predetermined position with high accuracy. Contributes to highly reliable nut supply.

[Brief description of drawings]

FIGS. 1 to 7 show an embodiment of the present invention. FIGS. 1 and 2 are vertical side views of a local portion, FIG. 3 is a three-dimensional view of a nut, and FIGS. 4 and 5 are supply rod tips. 6 is a vertical sectional side view of the entire apparatus, and FIG. 7 is a partial vertical sectional side view of the apparatus. 8 and 9 are external side views of the prior art. 12 ... Supply rod, 10 ... Projection nut, 13
…… Projection piece, 20 …… Tip corner of projection piece, 17 …… Fixed electrode, 18
……guide pin.

Claims (1)

(57) [Claims] 1. A projecting piece for holding a projection nut in a state of closely contacting the projection nut from below is provided at the tip of the supply rod, and the projection nut is attracted and held by magnetic force at the tip of the supply rod. With the relative position between the tip corner and the projection nut set, move the feed rod obliquely downward or almost horizontally, and immediately before the guide pin, the projection nut does not contact any steel plate parts or guide pin. The projection nut is caused to fall down about its tip corner by its own weight by eliminating the magnetic attraction force to the projection nut almost at the same time as the stop, and then the projection nut is aligned with the guide pin of the fixed electrode. Of the projection nut, which is characterized by being Feeding method.