JPS5928825Y2 - Structure of heat caulked joints of plastic parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the shape of the surface of a connecting portion that securely connects a plastic part and a metal part or other plastic parts by heat caulking.

Conventionally, when a plastic part and a mating part made of metal or plastic are firmly connected by heat caulking, a joining protrusion provided on the plastic part is inserted into a joining hole provided on the mating part, and the caulking tool is inserted from the tip of the joining protrusion. This is done by applying heat and force.

FIG. 1 is a schematic perspective view showing a heat caulking section of three parts that are heat caulked based on the conventional technology, in which a connecting protrusion 2 provided on a plastic component 1 is fitted into a connecting hole 4 provided on a mating component 3. It shows the state before.

FIG. 2 is a partial vertical cross-sectional view of FIG. 1, showing a mating part in a cross-sectional state.

This mating part can be either a metal part or a plastic part.

After fitting the connecting protrusion 2 of the plastic part into the connecting hole 4 of the mating part 3, heat and pressure is applied from the tip of the connecting protrusion 2. Due to the thermoplasticity of the plastic, the connecting protrusion 2 is caulked as shown in Fig. 3. 5 and crimped head 6.

At this time, the caulking tool 9 that heats and presses the connecting protrusion 2 is the fourth one.
As shown in the figure, a caulking head 1 is formed by a caulking surface 10 of a caulking tool 9.

By heat caulking, the connecting protrusion 2 increases in diameter to the extent that it applies internal pressure to the connecting hole 4 of the mating part 3 and becomes a caulking condyle 5, and the part exceeding the volume of the connecting hole 4 is formed on the upper surface of the mating part 3. The caulking head will be 6.

The caulking force between the heat-sealed plastic part 1 and the mating part 3 is usually expressed as the force required to separate them in the pulling direction 9 in FIG.

Therefore, the caulking force is the sum of the tensile strength at the lower surface 8 of the caulking head and the contact force between the caulking condyle 5 and the inner surface of the connecting hole 4.

Therefore, the key to designing heat-staking parts and hot-staking work is to achieve the above-mentioned swaging force above the desired value in the shortest possible time without causing deterioration of physical properties due to deterioration of the plastic material of the connecting protrusion 2. be.

However, in the prior art, the connecting protrusion 2 and the connecting hole 4
It is a matter of appropriately selecting the dimensional difference in the mating cross section before heat caulking and the ratio of the volume of the connecting protrusion 2 to the volume of the connecting hole 4.

Therefore, it is difficult to modify and change the working conditions of heat staking each time in response to the above-mentioned dimensional difference error or volume-volume ratio error.

In this way, it is difficult to expect the uniformity of the crimping force with hot crimped products using conventional technology, and the connecting protrusions 2 and the connecting holes 4 are designed to be larger in order to ensure the minimum required crimping force. This resulted in a loss of economic efficiency.

The purpose of this invention is to overcome the above-mentioned drawbacks of the conventional technology, to ensure the magnitude and uniformity of the crimping force of the heat crimped product, and to design the connecting protrusion 2 and the connecting hole 4 to a necessary and sufficient size. However, it is an object of the present invention to provide a structure of a connecting portion that is advantageous in terms of economy in caulking and other processes.

In order to achieve the above-mentioned purpose, the structure of the connecting part is such that unevenness such as a lined knurling is provided on the opposing surfaces of the connecting protrusion 2 of the plastic parts 1 to be firmly connected and the connecting hole of the mating part 3. It is something to do.

The principle of the present invention will be explained in detail below with reference to the drawings.

Figure 5 is a diagram illustrating an embodiment of the present invention.
A flat knurling-like unevenness with a depth tl is provided for the outer diameter d.

In addition, parallel to this, the height t2 is set relative to the inner diameter of the connecting hole 4.
A knurling-like unevenness is provided on the flat surface.

When doing this, the caulking surface 10 of the caulking tool 9 is heated from the tip of the connecting protrusion 2, and the connecting protrusion 2
When the material is melted and pressurized, due to the unevenness of the flat knurling described above, the distance between the connecting hole 4 and the connecting protrusion 2 is not uniform in each diametrical direction, so the melted material does not flow in the same plane. It not only moves diametrically, but also circumferentially.

Such material movement can prevent the generation of voids that may occur at the interface between the plastic part 1 and the mating part 3 during caulking.

Although the connection between plastic parts and other parts by means of knurling is used in plastic injection molding, in the present invention, the molten resin is solidified and fixed around the knurling. Regarding the relationship between the connecting protrusion 2 and the connecting protrusion 2, a feature is that both or the connecting protrusion 2 are provided with knurling-like unevenness.

Table 1 shows specific examples of the present invention, and all symbols in the table have the shapes shown in FIG. 5.

Now, if the plastic part 1 is a molded product, it is a part of it.

The knurled grooves of the connecting protrusion 2 can be formed relatively easily by using a method such as electric discharge machining when manufacturing the cavity of the molding die, thereby making it possible to form the unevenness in the plastic part.

If the mating part 3 is a plastic molded product, if the required unevenness is formed on the outer surface of the core pin placed in the mold by grinding, knurling with a lathe, or sear machining, the mold can be used for connection. Knurling-shaped unevenness can be formed relatively easily on the inner surface of the hole 4.

The mating part is plate-shaped and is punched, and the plate material is usually 35 mm or less thick, and the die hole of the punch is knurled with a radius of 2.52.5 times the plate thickness relative to the punch. It can be easily formed by drilling the connecting hole 4 with a die that can punch out a hole in the shape of.

When the mating part 3 is machined, the connecting hole 4 is also often machined, and machining of the above-mentioned knurling-like irregularities requires broaching, so machining cannot be said to be easy.

In such a case, the connecting protrusion 2 of the plastic part 1
Even if the knurling-like unevenness is formed only in the mating part 3 and the knurling-like unevenness in the connecting hole 4 of the mating part 3 is omitted, there may be a practical problem.

As explained above, when the tree climbing structure is applied to the joints, it is possible to ensure the magnitude and uniformity of the caulking force of the heat-caulked product.
The connecting protrusion 2 and the connecting hole can be designed to have a necessary and sufficient size.

As a result, when connecting projections 2 having the same outer diameter are used, the number can be reduced by 30 to 40, and the total number of steps for heat caulking can be reduced by 30 to 40.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view showing a heat crimped portion of three parts according to the prior art, Fig. 2 1d is a partial vertical sectional view of Fig. 1, and Fig. 3 is a partial view showing the state after heat staking according to the conventional technology. longitudinal section,
Fig. 4 is an external view of the crimping tool, Fig. 5 is a vertical sectional view of an embodiment of the present invention. 1...Plastic parts, 2...Connecting protrusions, 3.
...Mating part, 4...Connection hole, 5...Clinching neck,
6... Crimping head, 7... Pulling direction, 8... Lower surface of caulking head, 9... Crimping tool, 10... Crimping surface.

Claims (1)

[Scope of utility model registration request] In the structure of a connecting part that firmly connects a plastic part and a metal part or a plastic part of a pond by heat caulking, the inner surface of the connecting hole provided in the metal part or other plastic part and the part that fits into this connecting hole. 1. A structure of a thermally swaged joint of plastic parts, characterized in that a knurling stepped unevenness is formed on both surfaces of the joint protrusion provided on the plastic part or on the surface of the joint protrusion.