JPS5923976B2 - Manufacturing method for bolts with knobs - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a bolt having a gripping knob on the head side.

Knob-equipped bolts, which have a synthetic resin knob on the head side of the bolt so that the knob can be grasped and screwed in or removed, are widely used in various types of equipment.

These bolts with knobs use a mold to mold the knob onto the head of the bolt, and in order for the knob to be attached to the bolt in a completely secure manner, the resin of the knob must cover the head of the bolt. It is necessary to rotate it to the back side.

The conventional method for manufacturing bolts with knobs is as shown in Figure 1.
One of the molds 2 and 3 forming the knob molding space 1 is provided with an insertion hole 6 into which the shaft portion 5 of the bolt 4 is inserted, and the molding space 1 is
The knob 8 was molded by supplying resin to the molding space 1 while the shaft portion 5 was inserted into the insertion hole 6 so that the head 7 was located at the position.

In the conventional molding method described above, a gap 9 is provided on the back side of the head T so that the resin of the knob wraps around, and in order to maintain this gap constant, the shaft 5 is placed in the shaft insertion hole 6. A positioning pin 10 that is in contact with each other is provided. For this reason, there was a problem in that the resin supplied to the molding space flows into the insertion hole 6 along the thread of the shaft portion 5, resulting in so-called burrs.

In order to prevent the occurrence of burrs, the diameter of the shaft insertion hole 6 must be made to be the same as the diameter of the shaft 5, but since the shaft has an error within a certain tolerance range, 6 is formed to have the maximum error diameter of the shaft portion 5, and therefore the occurrence of burrs cannot be completely prevented.

In addition, since the positioning pin 10 is used to maintain the gap 9 for the resin to rotate on the back side of the head 7, it is necessary to replace it when the length of the bolt changes, which is extremely time consuming and Even bolts with the same diameter have length errors, so there are problems such as the inability to maintain a constant space.

As mentioned above, if burrs occur, the product cannot be screwed in as it is, so it is necessary to remove the burrs.This deburring work is done manually, which is time-consuming and inefficient, and reduces the cost of the product. It is also a factor in increasing the

Furthermore, as shown in Fig. 2, it has been considered to manufacture a bolt with a knob using a thin-bodied bolt 4a with a thinner upper end of the shank, but in this case, burrs may form on the shank. is larger than in the case shown in Figure 1, so it was considered impossible to use narrow-body bolts.

This invention was made to solve the above-mentioned problems, and the knob molding space and the shaft insertion hole are bordered by an annular protrusion that comes into contact with the back surface of the head, so that the knob molding space and the shaft insertion hole are cut off by an annular protrusion that comes into contact with the back surface of the head. It is an object of the present invention to provide a method for manufacturing a bolt with a knob that does not cause inflow of resin and does not generate burrs.

Hereinafter, an explanation will be given based on FIG. 3 showing an embodiment of the present invention.

As shown in FIG. 3, a molding space 14 for the knob 13 is formed by the abutting molds 11 and 12, and one of the molds 11 is provided with an insertion hole 17 into which the shaft portion 16 of the bolt 15 is inserted.

In the molding space 14 of one of the molds 11, there is a shaft insertion hole 17.
An annular protrusion 18 is provided around the open end of the bolt 15 , and the back surface of the bolt 15 inserted into the shaft insertion hole 17 comes into contact with the annular protrusion 18 .

As shown in FIG. 3, the annular protrusion 18 is formed to have an outer diameter that leaves a space around the back surface of the head 19 for the resin to pass around.

The manufacturing method of the present invention is carried out using the mold as described above, in which the shaft portion 16 is inserted into the insertion hole 17, and the head 1 is inserted into the insertion hole 17.
Bolt 15 so that the back side of 9 abuts on the annular protrusion 18.
The molds 11 and 12 are assembled with the resin set in the mold 11, and resin is supplied to the molding space 14.

Since the head 19 of the bolt 15 contacts the annular protrusion 18, the molding space 14 and the insertion hole 17 are completely separated, and the resin injected into the molding space 14 to form the knob 13 is It only flows around the outer periphery of the annular protrusion 18 against the back surface of the portion 19 and does not flow into the insertion hole 17 side.

Therefore, no burrs are generated on the shaft portion 16, and the bolt with a knob that is taken out by separating the molds 11 and 12 is completed as a product without being subjected to any deburring process.

In the bolt with a knob manufactured in this manner, the portion located on the back surface of the head of the knob 13 has a space around the shaft portion 16 that corresponds to the annular protrusion 18 .

The shape of the knob 13 is just one example, and it is of course possible to form it into other shapes.

As described above, according to the manufacturing method of the present invention, the knob is molded with the molding space and the shaft insertion hole bordered by the annular protrusion that contacts the back surface of the bolt head.
The flow of resin toward the shaft is completely stopped, and the formation of burrs on the outer circumference of the shaft can be reliably prevented, making it possible to omit deburring work and reducing the labor required. This can result in a significant cost gain.

In addition, positioning can be performed by contacting the annular protrusion on the back of the head, and the positioning pin required in the past can be omitted, eliminating the need to replace the positioning pin, improving work efficiency, and improving the It becomes possible to manufacture bolts with knobs using bolts of different lengths using the same mold.

Furthermore, since there is no resin flowing into the shaft insertion hole, excellent effects such as the ability to use a narrow-bodied bolt for the bolt can be achieved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the conventional manufacturing method, FIG. 2 is a vertical cross-sectional view using a narrow-body bolt, and FIG. 3 is a vertical cross-sectional view showing the manufacturing method of the present invention. 11 and 12 are molds, 13 is a knob, 14 is a molding space, 15
16 is a bolt, 17 is a shaft inserter Ll8 is an annular projection, and 19 is a head.

Claims (1)

[Claims] 1. Using a mold with a bolt shaft insertion hole and a knob molding space, an annular protrusion is provided around the opening where the shaft insertion hole of this mold faces the knob molding space to receive the back surface of the bolt head. ,
The knob is molded by bringing the back side of the head of the bolt inserted into the shaft insertion hole into contact with the annular protrusion, and supplying resin to the molding space with a border between the knob molding space and the shaft insertion hole. A method for manufacturing bolts with knobs.