JPH029620A - Metal insert method to thermoplastic resin molded product and metal insert applied molded product - Google Patents

Abstract

PURPOSE:To reduce the generation of burr and to enhance the durability against pull-out force and turning torque by using an insert metal fitting wherein a specific groove is provided to an insert part and inserting said metal fitting by utilizing ultrasonic vibration. CONSTITUTION:Either one of or both of a lateral groove 6 and a longitudinal groove 7 are provided to the insert part of an insert metal fitting 1. The lateral groove 6 mainly contributes against the pull-out of the insert part and the longitudinal groove 7 mainly contributes to an increase in the holding force of the insert part to rotation. It is necessary to set the mean width of each of the grooves 6, 7 to 0.2-3mm and the mean depth thereof to 0.2-3mm. In inserting the inserting metal fitting under pressure to fix the same, the insert metal fitting is aligned with the hole part of a resin molded product to be inserted in said hole part under pressure while ultrasonic vibration is applied by an ultrasonic welding machine and the thermoplastic resin (the inner surface of the hole part) in contact with the insert metal fitting under pressure is melted by friction heat due to vibration and partially or entirely allowed to fill the grooves 6, 7 provided to the insert metal fitting to more strongly fix the insert metal fitting.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an improved method for applying metal inserts to a thermoplastic resin molded product using ultrasonic vibration, and a process for applying the metal inserts obtained thereby. Regarding molded products.

[Conventional technology and its issues]

Adding a metal insert to a thermoplastic resin molded product to create a functional part that integrates a resin part and a metal part is widely used as a method of making the most effective use of the properties of resin and metal.

One of the metal insert methods for such post-processing is a method in which a hole for the insert is provided in advance in the resin molded product, and an insert fitting is press-fitted into the hole using ultrasonic vibration. According to this method, the ultrasonic vibration applied to the upper part of the insert metal causes the insert metal to vibrate, and frictional heat is generated between this and the thermoplastic resin, and the resin is melted while the insert metal fitting is press-fitted. Therefore, compared to the method of simply press-fitting the insert fitting, this method has the advantage that unreasonable stress is less likely to be applied to 1% of the insert, and the adhesion between the resin and the insert fitting is relatively good.

However, resin and metal are inherently not compatible and have extremely poor adhesion, so even with the insert method using ultrasonic vibration, the insert metal fittings are often not fixed to the resin sufficiently, and the It was not possible to meet the requirements for items that required strong fixation.

For example, as shown in FIG. 1, while the head of an insert fitting 1 having a male thread is vibrated ultrasonically, it is embedded in a thermoplastic resin molded product 2 as shown in FIG. When tightened, the fixing force of the insert part cannot withstand the tightening force, causing problems such as the insert fitting easily rotating, being pulled upward, and coming off. In addition, as shown in FIGS. 4 and 5, not limited to this example,
A similar problem occurs in those in which some external stress is applied to the insert portion.

To address this problem, a method is known in which the surface of the insert portion of the insert metal fitting is made into a low-left shape in order to improve the fixing force between the resin and the metal insert fitting. However, not only is the low left processing complicated, but even with this method, a sufficient improvement in fixing force cannot be obtained in many cases. In addition, as shown in Figs. 4 and 5, when the hole for the insert provided in the resin molded product is penetrated, the molten resin peculiar to the ultrasonic insert is pushed by the insert fitting and remains as a lump. There is also the problem that post-processing is required.

[Means to solve the problem]

The inventors of the present invention have conducted extensive studies on a method to solve these problems with metal inserts that utilize ultrasonic vibration, and to make it possible to create metal inserts that have excellent fixing force between the resin and the insert metal fittings, and are less likely to generate flakes. As a result, the inventors discovered that the object could be achieved by forming the insert portion of the insert fitting into a specific shape, and arrived at the present invention.

That is, in the present invention, when inserting a metal into a thermoplastic resin molded product using ultrasonic vibration, the insert part of the insert fitting has (a) an average width of 0.2 to 3 mm and an average depth of 0.2 to 3 mm.
At least one groove (b) provided horizontally to the insert direction, with an average width of 0.2 to 3 m+n, and an average depth of 0.2 to 3 m+n.
3+11111, and a metal insert method characterized by using an insert fitting having one or both of at least one groove provided in a longitudinal direction with respect to the insert direction, and a method for applying a metal insert obtained thereby. Regarding molded products.

Hereinafter, the insert fitting of the present invention will be explained with reference to the drawings.

FIGS. 6 to 14 show various embodiments to which the present invention is applied, taking the metal insert shown in FIG. It is located in a place where one or both of 7.

Here, the horizontal groove 6 mainly acts to increase the holding force against the insert part coming off, and is preferably provided so as to form an angle of approximately 90 degrees with respect to the insert direction. It is also possible to tilt it.

Further, the vertical groove 7 mainly contributes to increasing the holding force against rotation of the insert part, and is preferably provided approximately parallel to the insert direction (angle of 0 degrees), but within a range of ±30 degrees. It may also be tilted.

In the present invention, only one of the horizontal grooves 6 and the vertical grooves 7 is formed in accordance with the external stress applied to the insert material of the molded product to which the insert is applied, that is, the pull-out force or rotational force. Although it is possible and effective to provide one (FIGS. 13 and 14), it is preferable to use both in combination.

In particular, the horizontal groove 6 is set at 90 degrees with respect to the insert direction,
It is particularly preferable to form the vertical groove 7 in the same direction as the insert direction (0 degrees), because the groove can be easily processed and the insert portion has an excellent fixing force.

Further, in the present invention, the average width of the grooves 6 and 7 is 0.
The depth should be 2 to 3 mm, and the average depth should be 0.2 to 3 mm. Specifically, preferred dimensions are appropriately selected from within this range depending on the dimensions of the insert fitting and the press-fitting margin.

Even if the width and depth of the groove are smaller than this, or conversely larger, firm fixation with the insert 11 cannot be expected.

That is, when the width and depth of the groove are small, the amount of resin filled in the groove is also small, and the resistance to pulling force or rotational force is
Only a slight improvement in fixing force can be obtained due to the shearing force of the resin. On the other hand, the resin approximately equivalent to the press-fitting margin of the insert metal fitting melts and a portion of it fills the groove, but if the width and depth of the groove are too large, the resin will only fill a portion of the groove. In this case as well, a sufficient improvement in fixing force cannot be obtained.

Preferably an average width of 0.3 to 2 mm and an average depth of 0.3 to 2 mm.
It is mm.

There is no particular restriction on the cross-sectional shape of the groove provided, and it can be any shape such as a quadrangle, trapezoid, triangle, or semicircle. Further, in accordance with the present invention, it is preferable that the groove 6 is a continuous groove over the entire circumference;
If it is about /4, there may be discontinuous portions, that is, portions where no grooves are cut (FIG. 11).

1l17 also has the function of guiding the melted resin to the groove 6 by ultrasonic vibration, so it is necessary to have a structure that connects the tip of the insert fitting and the groove 6, but it is not necessary to make the groove cover the entire insert part. (Figure 12).

In addition, the groove 7 is made slightly wider at the tip of the insert,
It is also a preferable method to form a tapered shape from this point to the later portions in order to make it easier to introduce the molten resin into the groove 6 (FIG. 9).

In the metal insert of the present invention, it is essential to provide at least one such groove 6 and/or groove 7. Usually, the length of the insert part in the insert direction and the outer circumferential length are considered, and the groove 6 is 1 to 5 grooves,
A sufficient effect can be obtained by providing an appropriate number of grooves 7 selected from the range of 1 to 10 grooves.

Further, combining the metal insert of the present invention with a known method, such as a method of forming the insert into a low-left shape, is advantageous (FIG. 10).

As mentioned above, the insert fitting used in the present invention is characterized by a structure in which a specific groove is provided in the insert part, and there are no particular restrictions on the shape or structure of other parts. do not have.

Next, the insert method in the present invention will be explained.

In the present invention, an insert fitting having a specific groove in the insert portion as described above is used to insert the thermoplastic resin molded product using ultrasonic vibration. At this time, it is necessary to provide a hole for press-fitting a metal insert in the resin molded product in advance by a molding means or by post-processing after molding.

To press-fit and fix a metal insert into a resin molded product with a hole for the insert, align the insert metal fitting with the hole in the resin molded product, place the horn of the ultrasonic welding machine on the top of the insert metal fitting, and apply ultrasonic Press fit the insert into the resin molded product while applying vibration. At this time, the thermoplastic resin (inner surface of the hole) that is in pressure contact with the insert fitting is melted by the frictional heat caused by the vibration, and a part or all of it is filled into the grooves 6 and 7 provided in the insert fitting of the present invention, and further Firmly fixed.

As described above, the present invention is characterized by a metal insert method, particularly an insert metal fitting, and the resin on which the metal insert is applied is not particularly limited as long as it is a thermoplastic resin, and any resin can be used. .

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to this.

Examples 1 to 10 and Comparative Examples 1 to 3 Insert metal fittings having the shape shown in Fig. 1 (outer diameter I of the insert part
Qmm, the length in the insert direction is 10 mm), the insert part is processed as shown in Table 1, and a polyacetal resin (POM) or polybutylene terephthalate resin (PBT) molded product (thickness It was press-fitted into a flat plate (1 Qmm in diameter) using ultrasonic vibration. The press-fitting allowance was approximately 8%.

Regarding the obtained insert molded product, the pull-out strength and turning torque of the insert metal fitting were measured, and the presence or absence of cracking was visually observed. The results are shown in Table 1.

For comparison, insert fittings not according to the present invention were similarly evaluated, and the results are also listed in Table 1.

〔Effect of the invention〕

As is clear from the above explanation and examples, by using an insert metal fitting with a specific groove in the insert part according to the present invention and inserting the metal fitting using ultrasonic vibration, the occurrence of burrs is reduced and the pull-out force is reduced. A molded product with a metal insert that has extremely high durability against turning torque can be obtained.

In addition, since the resin is press-fitted while being melted by ultrasonic vibration, there is no need to apply unreasonable stress, which eliminates stress cracking during press-fitting that occurs with metal inserts that are simply press-fitted, and various problems caused by residual stress after press-fitting. For example, it also has the advantage that it can be obtained with very little cracking due to heat cycles, solvent immersion, etc.).

[Brief explanation of the drawing]

Figures 1 and 3 are schematic front views showing an example of a general insert fitting, and Figures 2 and 4 are schematic views showing a state where these are inserted into a resin molded product and another member is fixed. It is an illustration. Moreover, FIG. 5 is a schematic diagram showing another aspect. 6 to 14 are schematic front views showing various aspects of the metal insert according to the present invention. 1: Insert metal fitting 2: Resin molded product 3: Another member 4: 〃 5: 〃 6: Horizontal groove 7: Vertical groove

Claims (1)

[Claims] 1. When inserting a metal insert into a thermoplastic resin molded product using ultrasonic vibration, the insert part of the insert fitting has (a) an average width of 0.2 to 3 mm and an average depth of 0.2 to 3 mm. 3mm
and at least one groove (b) provided in a direction transverse to the insert direction, with an average width of 0.2 to 3 mm and an average depth of 0.2 to 3 mm.
A metal insert method characterized by using an insert fitting having one or both of at least one groove provided in the vertical direction with respect to the insert direction. 2. A molded product provided with a metal insert by the metal insert method according to claim 1.