JPH07186263A - Bonding method for plastic member - Google Patents

Abstract

PURPOSE:To provide a bonding method which can bond plastic members in high quality, with high strength, and at low costs. CONSTITUTION:A running groove 3 is formed in a flange 1a. Flanges 1a, 2a are pressed to face each other so that the groove 3 is closed on the side facing the flange surface. In this state, hot air, the temperature of which exceeds the melting point of a thermoplastic resin, is supplied to pass through the groove 3 so that the flanges 1a, 2a are welded while they are facing each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for joining a plastic member containing a thermoplastic resin containing a first joining surface and a second joining surface which can face each other. This method is particularly suitable when the plastic member is a fiber reinforced product.

[0002]

2. Description of the Related Art Conventionally, as a method for joining plastic members, a heat fusion joining method and a vibration welding method have been known ("Adhesion Techniques" vol 12, No. 1 (1992), Vol. 26, pp. 9-10. , "Plastics" vol4
2, No. 5, pages 89-94). For example, as a heat fusion bonding method using a heating plate, as shown in FIG. 9A, a first plastic member 91 containing a thermoplastic is used.
A case will be described in which the first joint surface 91a formed on the first joint surface 91a and the second joint surface 92a that is formed on the second plastic member 92 containing a thermoplastic and can face the first joint surface 91a are joined. In this method, first, only the first and second joint surfaces 91a and 92a to be joined are heated. Therefore, a heating plate 93 heated to a temperature exceeding the melting points of both thermoplastics is prepared. , The second joint surfaces 91a and 92a are brought into contact with each other. As a result, as shown in FIG. 9B, the first and second joint surfaces 91a, 92
Since a is melted, as shown in FIG. 9C, the first and second joint surfaces 91a and 92a are separated from the heating plate 93, and as shown in FIG. Second
The joining surfaces 91a and 92a are faced while being pressed, and the first and second joining surfaces 91a and 92a are joined. In addition to the heating plate 93, an electric iron, burner or the like may be used.

Further, the vibration welding method is included in the above heat fusion bonding method in a broad sense because the first and second bonding surfaces are melted by frictional heat. In this vibration welding method, for example, the first and second bonding methods are used. At the same time as the pressure between the surfaces is applied, lateral vibration parallel to the first and second joint surfaces is applied with a lateral amplitude of several mm, and the friction heat generated thereby causes the first and second joint surfaces to join.

[0004]

However, with the above-mentioned conventional joining method, it is difficult to join the plastic members with high quality, high strength and low cost. That is, in the conventional thermal fusion bonding method, in order to melt only the first and second bonding surfaces to be bonded, the first and second bonding surfaces are melted apart from each other, and then they are faced to each other under pressure. By doing so, they are joined together. Therefore, it is easy to contaminate the plastic member or leave a contact mark when the plastic member is contacted with the heating plate or the like.
In addition, since a time lag is likely to occur from the melting to the pressing face-to-face contact, it is necessary to heat the first and second joint surfaces more than necessary, resulting in energy loss and physical properties of the plastic member after joining. There is also the possibility of a decrease.

Further, in this method, the vicinity of the first and second joint surfaces is only melted and pressure-bonded, and the melting does not proceed with the first and second joint surfaces facing each other. Therefore, the material flow is unlikely to occur in the deep range between the first and second joint surfaces. Therefore, since it is difficult to relax stress between the joined first and second joint surfaces, strain or deformation existing before joining tends to remain in the joined plastic member, and the joining strength is still insufficient. There are cases. Particularly when the plastic member is a fiber reinforced product, fiber reinforcement is hardly performed between the first and second joint surfaces, and the joint strength tends to be low.

On the other hand, in the conventional vibration welding method, the first and second methods are used.
Lateral vibration is merely performed to melt the joint surface with frictional heat, and frictional heat is less likely to be generated as the melting progresses. Normally, when melted, the vibration is stopped almost at the same time and the joining is finished by cooling. . For this reason, since the flow of the material between the first and second joint surfaces is unlikely to occur in a deep range, the joint strength is still insufficient due to residual stress, and particularly when the plastic member is a fiber-reinforced product. Since the melting depth and area are narrower than the shape of the reinforcing fibers, fiber reinforcement is hardly performed between the first and second bonding surfaces, and the bonding strength tends to be low.

In addition, in this method, since the joining is performed only by vibration, a relatively large amount of energy is required and the joining cost is increased. The present invention is
The present invention has been made in view of the above conventional circumstances, and an object of the present invention is to provide a joining method capable of joining plastic members with high quality, high strength, and at low cost.

[0008]

[Means for Solving the Problems]

(1) The method for joining plastic members according to claim 1 is a method for joining plastic members, in which a first joining surface and a second joining surface which are formed on a plastic member containing a thermoplastic and can face each other are joined. Then, a flow groove is formed on at least one of the first bonding surface and the second bonding surface, and the first bonding surface and the second bonding surface are opposed to each other while being pressed, so that the flow groove is in the facing direction. It is characterized in that it is in a closed state, and in this state, hot air having a temperature exceeding the melting point of the thermoplastic is circulated in the circulation groove to fuse the first joint surface and the second joint surface.

[0009] In the present invention, the hot air, inert gas so as not to change the physical properties of the plastic member, N _2,
Dry air or the like can be used. Further, in the present invention, as the thermoplastic, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polyamide or the like can be adopted.

Further, in the present invention, when the plastic member is a fiber reinforced product, as the reinforcing fiber, glass, boron, carbon, metal, ceramic whisker, etc. are adopted as the inorganic fiber, and vinylon, nylon, tetron as the organic fiber. , Cotton, hemp, etc. may be employed. (2) In the joining method according to claim 2, in the method according to claim 1, a frequency of 50 Hz or less is generated between the first joining surface and the second joining surface while circulating hot air, and the first joining surface and the A lateral vibration parallel to the second joint surface is applied to melt all of the first joint surface and the second joint surface, thereby fusing the first joint surface and the second joint surface. To do.

The frequency of lateral vibration applied while circulating hot air is 50 Hz or less. This frequency is preferably 10 Hz or less. When the frequency of the lateral vibration exceeds 50 Hz, it becomes difficult to supply the amount of heat due to hot air to the joint surface facing the flow groove, and the melting temperature becomes difficult to progress. Therefore, when the plastic member is a fiber-reinforced product, It becomes difficult to move between the first and second joint surfaces.

The amplitude of the lateral vibration is selected to be larger than the shape of the reinforcing fiber when the plastic member is a fiber reinforced product within the range where the closed flow groove is not opened.
For example, the plastic member is a fiber reinforced product, and usually has a fiber length of 0.1 to 20 mm and a diameter of 1 to 1000 μm.
When the reinforcing fiber is a glass chopped strand fiber having a fiber length of 0.2 mm and a diameter of 10 μm, the bonding margin of the first and second bonding surfaces is set to 2 mm or more, which is 10 times the fiber length, and the amplitude of transverse vibration is 10 times the fiber length. 2 mm or more.

(3) According to the joining method of claim 3, claim 1
In the method, immediately after melting a part of the first joint surface and the second joint surface by circulating hot air, the frequency between the first joint surface and the second joint surface is 100 to 250 Hz, and It is characterized in that the first bonding surface and the second bonding surface are fused by applying a lateral vibration parallel to the first bonding surface and the second bonding surface.

The frequency of transverse vibration applied immediately after the hot air is circulated to melt a part of the first and second joint surfaces is 100 to 25.
It is 0 Hz. If the frequency of lateral vibration is less than 100 Hz,
The part excluding the part melted by the hot air is less likely to be melted by the frictional heat of the lateral vibration, and when the plastic member is a fiber-reinforced product, the reinforcing fibers are less likely to move between the first and second joint surfaces. Also, if the frequency of lateral vibration exceeds 250 Hz,
The part except the part melted by hot air is excessively melted by frictional heat, and it is easy to increase the product error.

(4) According to the joining method of claim 4,
The method of (1) is characterized in that, in addition to transverse vibration, longitudinal vibration of 50 Hz or less, which has an amplitude equal to or less than the melting depth and is perpendicular to the first and second joint surfaces, is also applied. Here, the lateral vibration may be one-dimensional or two-dimensional, and in the case of two-dimensional, there are, for example, an elliptical motion and a circular motion. Also, three-dimensional motion combined with longitudinal vibration is possible. With such a configuration, the molten materials are mutually fluidized and mixed between the joint surfaces.

[0016]

[Action]

(1) In the joining method according to the first aspect, the first and second joining surfaces are opposed to each other while being pressed, whereby the flow groove is closed in the facing direction, and hot air is circulated in the flow groove in this state. At this time, since the temperature of the hot air exceeds the melting point of the thermoplastic, the first and second joint surfaces are melted. At this time, in the state where the first and second joint surfaces are pressed against each other,
When the heat is sufficiently transferred to the surroundings from the circulation groove, only the first and second joint surfaces to be joined are melted and fused.

Therefore, contamination of the plastic member can be avoided, and no contact mark is produced. Further, since there is no time lag and there is no need to heat the first and second joint surfaces more than necessary, energy loss does not occur and the physical properties of the plastic members after joining do not deteriorate. Further, since the melting proceeds in a state where the first and second joint surfaces face each other, the material is melted in a deep range between the first and second joint surfaces. Therefore, stress is relieved between the joined first and second joint surfaces, strain and deformation existing before joining do not easily remain in the joined plastic member, and sufficient joining strength is ensured.

Further, even if the vibrations are simultaneously performed, the energy of the hot air and the energy of the vibrations are both supplemented, so that a relatively small amount of energy is sufficient and the bonding cost can be reduced. (2) In the joining method of claim 2, the first and second joining surfaces are melted exclusively by hot air, and frictional heat due to lateral vibration is not used at all. At this time, the material is generated in a deep range between the first and second joint surfaces due to the lateral vibration, and particularly when the plastic member is a fiber-reinforced product, the fiber reinforcement is more easily performed between the first and second joint surfaces, It tends to have high bonding strength.
The reason for this is that the reinforcing fibers are reinforced by straddling the first and second joint surfaces.

(3) In the joining method according to claim 3, a part of the molten material melted by the hot air is mixed with a material of a part melted by the frictional heat of the lateral vibration, so that the plastic member is a fiber reinforced product. When it is, it becomes easy for the reinforcing fiber to be reinforced by straddling the first and second joint surfaces. That is, the material flow occurs between the first and second joint surfaces in a deep range, and particularly when the plastic member is a fiber-reinforced product, the fiber reinforcement is more likely to be performed between the first and second joint surfaces. It tends to have high strength. Further, since the frequency of the lateral vibration does not exceed 250 Hz, the part except the part melted by the hot air is not excessively melted by the frictional heat, and the product error is small.

(4) In the joining method according to the fourth aspect, when the plastic member is a fiber reinforced product, the molten material is more fluidly mixed between the first and second joining surfaces, and the reinforcing fiber is between the first and second joining surfaces. Strengthen by straddling. That is, the material flow occurs between the first and second joint surfaces in a deep range, and particularly when the plastic member is a fiber-reinforced product, the fiber reinforcement is more likely to be performed between the first and second joint surfaces. It tends to have higher strength.

[0021]

EXAMPLES Examples 1 and 2 embodying the present invention will be described below along with tests with reference to the drawings. (Embodiment 1) Embodiment 1 embodies claims 1, 2 and 4. In Example 1, as shown in FIG. 1, first and second plastic members both made of 70% by weight of nylon 66 and 30% by weight of glass fiber (fiber length 0.2 mm, glass chopped strand having a diameter of 10 μm). Cases 1 and 2 are joined together. These cases 1,
2 is separately injection-molded, and the cases 1 and 2 have flanges 1 as first and second joint surfaces which can face each other.
a and 2a are formed.

The flange 1a of the case 1 is shown in FIG.
As shown in FIG. 3, the flow groove 3 having a V-shaped cross section has a flange 1a.
1 is encircled, and as shown in FIG. 3 (A), the flow groove 3 is opened laterally by the adjacent openings 3a and 3b. Note that, in FIGS. 2A to 2C, the orientation state of the glass fiber is shown by a thin line. Inside the distribution groove 3, the distribution groove 3
And a burr escape groove 4 parallel to the circulation groove 3 is engraved around the flange 1a, and a burr escape groove 5 parallel to the circulation groove 3 is provided outside the circulation groove 3 except for a portion blocked by the openings 3a and 3b. It is engraved around the.

Further, the flange 2a of the case 2 has a structure shown in FIG.
As shown in (A), burr escape recesses 6 and 7 facing the burr escape grooves 4 and 5 are provided. Flange 1a,
The joining margin excluding the widths of the flow groove 3, the burr escape grooves 4, 5 and the burr escape recesses 6, 7 in 2a is 2 mm or more, which is 10 times the fiber length of the glass fiber. The flow groove 3, the burr escape grooves 4 and 5, and the burr escape recesses 6 and 7 are shaped by the molding dies of the cases 1 and 2.

Then, as shown in FIG. 3B, the flange 1a and the flange 2a are faced while being pressed, and the flow groove 3 is closed in the face-to-face direction. In this state, the cases 1 and 2 are sandwiched and connected to a converter (not shown) as a vibrating body. In this state, a nozzle (not shown) is brought into contact with the opening 3a, and the melting point of the nylon 66 is slightly exceeded from the opening 3a shown in FIG. 3 (B) according to the time chart shown in FIG.
Hot air at a temperature of up to 190 ° C. is pressure-fed at intervals of ten and a few seconds while gradually increasing the gas pressure, and is circulated in the flow groove 3 and discharged from the opening 3b. At this time, an inert gas is used as the hot air. Here, if the temperature of the hot air is set too high, the nylon 66 will be decomposed, so care must be taken.

At the same time, vibration is applied between the flanges 1a and 2a while gradually lowering the vibration speed at intervals of ten and several seconds. At this time, a vibration speed of 10 Hz, an oval amplitude of 2 mm, and a longitudinal amplitude of 1 mm, and then 5 H.
Vibration frequency of z, lateral amplitude of 2 mm and longitudinal amplitude of 1 mm, vibration frequency of 2 Hz, vibration speed of lateral frequency of 2 mm, longitudinal amplitude of 0.5 mm, continuous vibration of 1 Hz The vibration velocity is such that the number has a lateral amplitude of 1 mm and a longitudinal amplitude of 0.2 mm. During this time, the melting of the flanges 1a and 2a is performed exclusively by hot air. For this reason, melting is promoted by the hot air, and at the same time, the glass fiber is reinforced by the elliptical vibration and the longitudinal vibration so as to straddle the flanges 1a, 2a. After this, the vibration is stopped and air cooling is performed.

In the first embodiment, the flange 1 is heated by hot air.
Since the elliptical vibration and the longitudinal vibration of 50 Hz or less are applied between the flanges 1a and 2a at the same time that the a and 2a are melted, the flow of the nylon 66 and the glass fiber melted between the flanges 1a and 2a is deep Occurs, the flange 1a,
Fiber reinforcement is more likely to occur between 2a and the joint strength tends to be higher.

Thus, as shown in FIG. 5, the case 1,
Two are fused together. In this case 1, 2, the flange 1
a and 2a face each other, melting progresses, and the flange 1
The flow of the nylon 66 and the glass fiber melted between a and 2a occurs in a deep range, and fiber reinforcement is performed between the flanges 1a and 2a. Therefore, stress is relaxed between the joined flanges 1a, 2a, strains and deformations existing before joining are less likely to remain in the cases 1, 2 after joining, and the joining strength is sufficiently secured.

Further, the cases 1 and 2 are free from contamination and contact marks. At this time, no time lag occurs and the flanges 1a and 2a are not heated more than necessary, so that energy loss does not occur and the cases 1 and 2 after joining do not deteriorate in physical properties. Further, even if the vibration is performed at the time of melting, the energy of the hot air and the energy of the vibration are used for joining. Therefore, a relatively small amount of energy is sufficient, and the joining cost can be reduced.

Further, heat is transferred from the circulation groove 3 to the surroundings,
Since the burr at the time of joining is accommodated by the burr escape grooves 4 and 5 and the burr escape recesses 6 and 7, there is almost no burr in the cases 1 and 2 after the joining, and the case has excellent appearance.
Further, since the frequency of the lateral vibration does not exceed 250 Hz, the part except the part melted by the hot air is not excessively melted by the frictional heat, and the product error is small.

Therefore, in the first embodiment, the cases 1 and 2 can be joined with high quality, high strength and low cost. In addition, in the first embodiment, since the melting and the vibration by the hot air are performed at the same time, the working time can be shortened. (Test) A case in which a fiber-unreinforced product case was fused by the method shown in FIG. 9, a case in which a fiber-reinforced product case was fused by the method shown in FIG. The base material strength and the fusion strength were compared between the case of fusion by the method of No. 1. The results are shown in Table 1.

[0031]

[Table 1] From Table 1, it can be seen that the method of Example 1 can provide high bonding strength even when the plastic member is a fiber reinforced product. This is because the method of Example 1 facilitates fiber reinforcement as the molten resin moves. Therefore, it can be seen that high bonding strength can be obtained even when the method of Example 1 is applied to a fiber-unreinforced product. (Embodiment 2) Embodiment 2 is one in which claims 1 and 3 are embodied. The second embodiment has the same configuration as that of the first embodiment except that the time chart is different. Therefore, the same components are designated by the same reference numerals, and the same operation and effect are omitted.

That is, the flange 1a and the flange 1a
In the state where they are faced while being pressurized and connected to the converter as the vibrating body, according to the time chart shown in FIG.
The hot air is pressure-fed at a predetermined gas pressure for about 30 seconds, circulates in the flow groove 3, and is discharged from the opening 3b. As a result, the flanges 1a and 2a are partially melted. At this time, in the state where the flanges 1a, 2a are pressed against each other, the flow groove 3
Since the heat is transmitted from the inside to the surroundings, only the flanges 1a and 2a to be joined are melted. Further, since the inert gas is circulated as the hot air, the physical properties of the flanges 1a and 2a do not change.

Subsequently, the frequency of 100 to 250 Hz,
At a vibration velocity such that a lateral amplitude of 2 mm is obtained, only one-dimensional lateral vibration of the flanges 1a, 2 shown in FIG.
Give between a. At this time, a part of the molten resin of the flanges 1a, 2a melted by the hot air is mixed with the material of the part melted by the frictional heat of the lateral vibration, and as a result, the flanges 1a, 2a in the material are crossed over. It becomes easier to intervene. After this, the vibration is stopped and air cooling is performed.

Therefore, also in the second embodiment, the cases 1 and 2 can be joined with high quality, high strength and low cost. It should be noted that as the circulation groove, a circulation groove 8 having a U-shaped cross section shown in FIG. 7 and a plurality of circulation grooves 9a to 9c engraved in the case 1 and the case 2 shown in FIG. 8 can also be adopted.

[0035]

【The invention's effect】

(1) As described in detail above, in the method for joining plastic members according to the first aspect, since the configuration according to the first aspect is adopted, the plastic members can be joined with high quality, high strength, and low cost. . That is, since the number of defective plastic members after joining is reduced and the equipment cost is low, the joining cost can be reduced.

Further, since sufficient bonding strength can be secured,
The appearance of the product can be improved by reducing the joining margin of the plastic member after joining. (2) In the joining method according to claim 2, the material flows between the first and second joining surfaces in a deep range, and particularly when the plastic member is a fiber reinforced product, the first and second joining surfaces are joined. Since the fiber reinforcement is more likely to be performed, high joint strength can be obtained.

Further, since the melting and the vibration by the hot air are performed at the same time, the working time can be shortened, so that the bonding cost can be further reduced. (3) Also in the joining method according to claim 3, the flow of material occurs between the first and second joining surfaces in a deep range, and particularly when the plastic member is a fiber reinforced product, the first and second joining surfaces are joined. Since fiber reinforcement is more likely to be carried out, high joint strength can be obtained.

(4) In the joining method according to the fourth aspect, higher joining strength can be obtained when the plastic member is a fiber reinforced product.

[Brief description of drawings]

FIG. 1 is a perspective view of each case used as a joint in Examples 1 and 2. FIG.

FIG. 2 is a partial cross-sectional view showing the flange of the case in the first embodiment.

FIG. 3 relates to the flange of the case in the first embodiment,
(A) is a partial plan view and (B) is a partial side view.

FIG. 4 is a time chart showing the relationship between hot air gas pressure, vibration speed, and time in Example 1.

5 is a partial cross-sectional view of the case joined in Example 1. FIG.

FIG. 6 is a time chart showing the relationship between hot air gas pressure, vibration speed, and time in Example 2.

FIG. 7 is a partial cross-sectional view showing a flange of a case according to another embodiment.

FIG. 8 is a partial cross-sectional view showing a flange of a case according to another embodiment.

FIG. 9 is a cross-sectional view of a conventional heat fusion bonding method.

[Explanation of symbols]

 1, 2 ... Case (plastic member) 1a, 2a ... Flange (first and second joint surfaces) 3, 8, 9a, 9b, 9c ... Flow groove

Claims (4)

[Claims] 1. A method of joining a plastic member, comprising: joining a first joining surface and a second joining surface, which are formed on a plastic member containing a thermoplastic and can face each other, to the first joining surface and the second joining surface. A flow groove is engraved on at least one of the second joint surfaces, and the first joint surface and the second joint surface are made to face each other while being pressed, whereby the flow groove is closed in the facing direction, and in this state, The hot air having a temperature higher than the melting point of the thermoplastic is circulated through the flow groove so that the first
A method for joining plastic members, characterized in that the joining surface and the second joining surface are fused together. 2. A first joint surface and a second joint surface while circulating hot air.
A frequency of 50 Hz or less is applied between the joint surfaces to give a transverse vibration parallel to the first joint surface and the second joint surface to melt all of the first joint surface and the second joint surface, The first
The method for joining plastic members according to claim 1, wherein the joining surface and the second joining surface are fused together. 3. Immediately after melting a part of the first joint surface and the second joint surface by circulating hot air, a frequency between the first joint surface and the second joint surface is 100 to 250 Hz. The joining of plastic members according to claim 1, wherein the first joining surface and the second joining surface are fused by applying a lateral vibration parallel to the first joining surface and the second joining surface. Method. 4. The plastic member according to claim 2, wherein the transverse vibration is simultaneously applied with a longitudinal vibration of 50 Hz or less, the amplitude of which is less than the melting depth and which is perpendicular to the first and second joint surfaces. Joining method.