JP4003698B2 - Laser welding method and laser welding apparatus for resin parts - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a finished product which meets no required welding strength due to a gap generated in the welded part from being manufactured. <P>SOLUTION: The joint flange part 4a of a half component 4 which absorbs a laser light 6 and a joint flange part 5a of a half component 5 which allows transmission of the laser light 6, are butted to each other and weld-joined at a joint area 9 by emitting the laser light 6. The laser welding is divided into two processes, i.e. tack welding and regular welding and in the meantime, an airtightness test is conducted. In the tack welding, when a gap G exceeds the tolerance limits G<SB>0</SB>, a compatible layer 14 is not formed and therefore, the judgement of the airtightness test results is "leakage present". Consequently, the half component 5 is rejected as a non-conforming article before applying the regular welding. On the other hand, the gap G falls within the tolerance limits G<SB>0</SB>in the tack welding, it is judged that the compatible layer 14 is formed and "no leakage is present" and therefore, the regular welding is applied for the first time. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser welding (laser welding) method and a laser welding apparatus for resin parts formed of a synthetic resin material, and in particular, one resin member and the other resin member are joined by welding by laser light irradiation. The present invention relates to a laser welding method and a laser welding apparatus for resin parts.
[0002]
[Prior art]
As a laser welding technique for this type of resin component, the one described in Patent Document 1 is known. In the technique described in Patent Document 1, a laser member that transmits a laser beam and a resin member that absorbs the laser beam are superposed on each other and then irradiated with the laser beam from the resin member side that transmits the laser beam. It is based on melting and joining a part of the resin member that absorbs the resin, and melting and bonding the resin member that transmits the laser beam with the heat of fusion.
[0003]
That is, when resin parts such as the above laser welding are welded and joined, a joining flange part to be a welding margin is formed in advance on the peripheral part of each resin member, and these joining flange parts are butted together. The laser heads that are to be irradiated with laser light are moved along the joint flange portion by NC control or the like, for example, and then welding is continuously performed.
[0004]
[Patent Document 1]
Japanese Examined Patent Publication No. 62-49850 (Page 2 and Fig. 1)
[0005]
[Problems to be solved by the invention]
In laser welding of such resin parts, there is a problem that if there is a gap between the resin members to be welded, the welding strength is extremely reduced.
[0006]
That is, at the time of laser welding of resin parts, the resin member that absorbs the laser beam first generates heat and melts, and then the heat of fusion is transmitted to the resin member side that transmits the laser beam with heat conduction to transmit the laser beam. The resin member is also melted, and as a result, both the resin members are melted and welded. In this case, if there is a gap between the two resin members, the heat conduction performance is extremely deteriorated, and the resin members are not sufficiently fused with each other, so that the welding strength between them is extremely reduced.
[0007]
Therefore, as a method for preventing the occurrence of poor welding strength, measure the size of the gap between the two resin members to be welded before irradiating the laser beam, and the size of the gap is an allowable limit. If the value is exceeded, it is considered effective to exclude the corresponding resin member. However, since the size of the gap between the two resin members is very small, it is extremely difficult to quantitatively measure the minute gap, and there is still room for improvement.
[0008]
As another method, after performing laser welding, an airtight test of resin parts is performed, and whether the welding strength is good or not is determined based on the “presence or absence of leakage” between the resin members forming the resin parts. Although it is possible, even if the welding strength is not sufficient, as long as both resin members are even slightly fused together, it will be judged as `` no leak '' in the airtightness test, and the result of the suitability judgment of the welding strength The reliability of is poor.
[0009]
The present invention has been made paying attention to the above-described problems, and in particular, a defective weld strength due to the occurrence of a gap between two resin members is accurately detected, and thus the resin component having the poor weld strength. Therefore, it is an object of the present invention to provide a laser welding method and a laser welding apparatus that can reliably eliminate the above.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, the bonding flange portions formed in advance as welding margins on the one resin member that transmits the laser beam and the other resin member that absorbs the laser beam are brought into contact with each other. A laser welding method for resin parts integrated by irradiating a laser beam from the bonding flange side of a resin member to weld the resin members together, and the welding by laser light is a two-step process including a temporary welding process and a main welding process. In addition, the airtightness test of the resin parts is performed after the temporary welding and before the main welding, and the main welding is performed only on the resin parts for which the result of the airtightness test is appropriate.
[0011]
In this case, as described in claim 2, it is preferable that the temporary welding is performed with a dose of laser energy smaller than that in the main welding, and more desirably, the temporary welding is performed as described in claim 3. Is performed with a laser energy dose that is less than the laser energy dose required to obtain the required welding strength, while this welding is performed with the laser energy dose required to obtain the required welding strength. .
[0012]
In addition, the change of the laser energy dose between the temporary welding and the main welding is, as described in claim 4, the laser output, the relative movement speed between the resin member and the laser beam, the laser head and the laser irradiation site, It can be given as a change of at least one of the distances formed by
[0013]
The invention according to claim 5 is the one in which the technique according to claim 1 is substantially regarded as a laser welding apparatus, and includes one resin member that transmits laser light and the other resin member that absorbs laser light. Each of the resin parts is made such that after joining the joining flange portions formed in advance as welding allowances, the resin members are welded and integrated by irradiating laser light from the joining flange portion side of one resin member. Assuming the laser welding device, the two resin members are positioned and clamped, and apart from the means for relatively moving and moving the resin members and the laser beam, the resin members are kept in an airtight state while maintaining the positioning clamp state between the resin members. It is characterized by having an airtightness test means for performing a sex test.
[0014]
Therefore, in the first aspect of the present invention, if the gap between the two resin members is within an allowable range, both the resin members are melted even at the stage of temporary welding. Even if the airtightness test is performed, no leakage occurs. In other words, if there is no leak in the airtightness test, the probability that the gap between the two resin members is within the allowable range is high, and the process proceeds to the main welding to ensure the required welding strength as it is. .
[0015]
On the other hand, if the gap between the two resin members is outside the allowable range, the two resin members do not melt together at the stage where only temporary welding has been performed, and therefore when the airtightness test is performed. There will be leakage. In other words, if leaks are observed in the airtightness test, there is a high probability that the gap between the two resin members is outside the allowable range, and welding is performed at that stage without shifting to the main welding. Eliminate as strength failure. By doing so, it is possible to prevent the resin component having poor welding strength from flowing out.
[0016]
In this case, by using the apparatus according to the fourth aspect, not only the temporary welding and the main welding but also the airtightness test can be performed in the same process.
[0017]
【The invention's effect】
According to the first aspect of the present invention, welding by laser light is performed in two steps, a temporary welding step and a main welding step, and after the temporary welding and before the main welding, an airtight test of the resin parts is performed. This is because the main welding is performed only for the resin parts for which the result of the airtightness test is appropriate, so that it is possible to prevent the occurrence of a product with poor welding strength based on the generation of a gap between the two resin members. There is.
[0018]
According to the fourth aspect of the present invention, since even a gas tightness test can be performed in the laser welding process, there is an effect that productivity is improved together with a reduction in the number of processes.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
1 and the following drawings show a preferred embodiment of the present invention, and show an example in which a resin intake manifold in an internal combustion engine is welded as a resin part as shown in FIG.
[0020]
As shown in FIG. 2, the intake manifold 1 as a resin part is formed as a substantially flat rectangular tubular structure as a whole, and has a plate-like shape at both ends in the longitudinal direction for connection with a mating member. The mounting flange portions 2 and 3 are integrally formed. In forming such an intake manifold 1, as shown in FIG. 3, two halved parts 4 and 5 which are resin members having joint flanges 4a and 5a formed on the entire circumference are preliminarily formed by, for example, injection molding. After forming and joining the joining flange portions 4a and 5a of the half parts 4 and 5 to each other, the joining flange portions 4a and 5a are integrated as a welding margin by performing welding joining with the laser beam to the portion, As a result, an intake manifold 1 as shown in FIG. 2 is obtained. The pair of mounting flange portions 2 and 3 are formed integrally with one half component 4 in advance.
[0021]
Of the two halved parts 4, 5, one half part 4 has a characteristic of absorbing laser light, and the other half part 5 has a characteristic of transmitting laser light. The component 4 is molded with a resin material that absorbs the laser beam 4, and the other half component 5 is molded with a resin material that transmits the laser beam. For example, when each of the halved parts 4 and 5 is injection-molded, one halved part 4 is molded using a PA6GF reinforcing material mixed with a colorant that absorbs laser light as the resin material, and the other halved part 4 is molded. The part 5 is molded using a resin material in which a PA6GF reinforcing material is mixed with a colorant that transmits laser light.
[0022]
As shown in FIG. 4, welding by irradiation with the laser beam 6 is abutted so that the joining flange portions 4 a and 5 a of both halved parts 4 and 5 are overlapped with each other, and pressed by a pressing jig 15 described later. Shall be performed. If the laser head 7 irradiates the spot-like laser beam 6 from one half-part 5 side, the laser head 7 and the half-parts 4 and 5 are divided into two in the width dimension of the joint flange portions 4a and 5a. Such a virtual welding line, that is, the laser beam 6 is relatively moved along the locus 8 to be moved. For example, the joining flange portions 4a and 5a are welded together by moving the laser head 7 along the laser beam locus 8 by NC control or the like with the halved parts 4 and 5 as the fixed side.
[0023]
FIG. 5 shows the entire structure of the laser welding apparatus including the laser head 7 and the holding jig 15. The laser head is supported on the tip of an arm 17 of an articulated industrial robot (hereinafter simply referred to as a robot) 16. In addition to 7, a work base 18 and a leak tester 12 as an airtightness test means are prepared. Each of the work base 18 and the leak tester 12 is provided with a sealing jig 10 or 11, and the mounting flange portions 2 and 3 of the half component 4 to be welded are respectively connected by bolts 19 to the sealing jig 10 or 11. 11 is fixed. Then, if the other half part 5 is superposed on the half part 4, both the half parts 4, 5 are pressed by the metal holding jig 15 so that the positioning clamp Is done.
[0024]
The holding jig 15 is a frame-shaped member that is formed in substantially the same shape as the joining flange portion 5a of one half-part 5. The holding jig 15 moves up and down in accordance with the expansion and contraction operation of the air cylinder 20. It plays the role which contacts the upper surface of the peripheral part of the part 5a, and adheres both joining flange parts 4a and 5a. The holding jig 15 is set so as not to interfere with the laser beam movement locus 8 described above, and the laser beam 6 is moved along the laser beam movement locus 8 inside the holding jig 15 during laser welding. Will move.
[0025]
That is, as shown in FIG. 6, one half component 5 transmits the laser beam 6 and the other half component 4 absorbs the laser beam 6. The laser beam 6 that has passed through is absorbed by the joint flange portion 4a of the other half component 4 at the joint surface 9 (the mating surface between the joint flange portions 4a and 5a), and a part of the joint flange portion 4a is melted. Let At the same time, a part of the joining flange portion 5a of the other half component 5 is melted by receiving the heat of fusion, whereby both the joining flange portions 4a and 5a are welded and joined together with the compatible layer.
[0026]
In this case, it is ideal that both the joining flange portions 4a and 5a closely contact each other at the joining surface 9, but a gap is generated on the joining surface 9 due to the molding accuracy of each of the halved parts 4 and 5. In some cases, the gap between the joint flange portions 4a and 5a has a great influence on the welding strength (joint strength) of the two.
[0027]
FIG. 7 shows an example of the relationship between the gap between the joint flange portions 4a and 5a and the welding strength. For example, when the required welding strength is 30 MPa, the joint flange portions 4a and 5a The required strength cannot be satisfied unless the gap between them is 0.1 mm or less. The allowable limit of the gap between the joint flange portions 4a and 5a is set to 0.1 mm because the laser beam 6 necessary for obtaining the required welding strength of the joint portion 9 between the joint flange portions 4a and 5a. When the laser output as the energy of 75 W is, for example, 75 W, and welding is performed with a laser output lower than, for example, 30 W, if the gap between the joining flange portions 4 a and 5 a exceeds 0.1 mm, the welding is performed. This is because it has been experimentally confirmed that the joint surface 9 which is a part becomes airtight and leaks.
[0028]
Therefore, in the present embodiment, as shown in FIG. 8, the laser welding as described above is performed in two steps of temporary welding and main welding, while the gap between the joint flange portions 4a and 5a and the welding are performed. By using the correlation with the strength, the suitability of the gap between the joining flange portions 4a and 5a and the welding strength is determined by an airtight test after the temporary welding and before the main welding.
[0029]
The temporary welding, which is the first welding, is a laser energy dosage (here, laser power) smaller than the laser energy dosage (here, for example, 75 W at the laser power level) required to obtain the required welding strength. Laser welding is performed under an output level of 30 W, for example, and an airtightness test is subsequently performed.
[0030]
As apparent from FIGS. 4 and 5, the laser welding apparatus includes a work base 18 having a sealing jig 10 corresponding to one mounting flange portion 3 and a sealing jig 11 corresponding to the other mounting flange portion 2. Since the leak tester 12 as an airtightness test means provided with a pre-attachment and the intake manifold (intake manifold in the intermediate forming stage) 1 after the temporary welding is positioned and clamped in advance to them, the temporary welding is followed. In this state, the leak tester 12 performs an airtight test with the inside of the intake manifold 1 as a sealed space. This airtightness test is a known method for determining pass / fail by monitoring a pressure change within a predetermined time in a state where a negative pressure or a positive pressure is applied until the inside of the intake manifold 1 reaches a predetermined pressure. It is.
[0031]
(A) in FIG. 1, the joint flange portion 4a after the temporary welding is welding margin, between the 5a between gap G within the allowable range G ₀ (0.1 mm or below) is of the joint surface 9 A schematic cross-sectional view is shown. As can be seen from the figure, if the gap G is within the allowable range G ₀ , the joining flange portions 4a and 5a are melted and welded to each other even in the temporary welding with a reduced laser energy dose. In addition, there is no leakage in the airtightness test. In addition, in the joining surface 9 which is a welding part, the material of the one joining flange part 4a side fuse | melts, and the bulging part 13 is formed, and the top part of this bulging part 13 contacts the other joining flange part 5a. Both are welded by forming the compatible layer 14. Accordingly, in the case of FIG. 1 (A), both of the joint flange portions 4a and 5a after the temporary welding are securely in contact with each other with the compatible layer 14 of the bulging portion 13, so that leakage occurs in the airtightness test. There is no occurrence.
[0032]
On the other hand, the bonding surface of the case (A) of FIG. 9 is the joint flange section 4a is welding margin, the gap G 5a between tolerance G ₀ outside (those exceeding 0.1 mm) after the temporary welding 9 is a schematic cross-sectional view of FIG. As is apparent from the figure, if the gap G exceeds the allowable range G ₀ , the welding flange portions 4a and 5a are not melted at the time of temporary welding with a reduced laser energy dose, resulting in insufficient welding. Therefore, leakage occurs in the airtightness test. That is, even if the material on one side of the joining flange portion 4a is melted to form the bulging portion 13, it does not sufficiently contact the other joining flange portion 5a. Such a compatible layer 14 is not formed and welding is insufficient. Therefore, in the case of FIG. 9A, since both the flange portions 4a and 5a after the temporary welding are not in close contact with each other at the bulging portion 13, a leak is surely generated in the airtightness test. 1 and 9 are both enlarged views of the cross section taken along the line DD in FIG.
[0033]
As shown in FIG. 8, the occurrence of leakage in the airtightness test after provisional welding is immediately excluded as a defective product based on whether the airtightness test is good or bad. Only those which did not occur are subjected to the main welding as the second welding described later. Thereby, it is possible to prevent a product that does not satisfy the required welding strength at the joint surface 9 between the joint flange portions 4a and 5a from flowing out to the subsequent process.
[0034]
This welding, which is performed as a second welding following the airtightness test, has a laser energy dose (for example, 75 W at the laser output level as described above) necessary to obtain the required welding strength. And laser welding.
[0035]
FIG. 1B is a schematic cross-sectional view of the bonding surface 9 as a welded portion when the main welding is performed subsequent to the temporary welding in FIG. As is apparent from the figure, at the joining surface 9 which is the welded portion, the bulging portion 13 on the side of the one joining flange portion 4a is further grown upon receiving the laser energy at the time of the main welding, so that a wider range, that is, a larger compatibility. The layer 14 is in contact with the other joining flange portion 5a so that they are welded together. Therefore, sufficient welding strength that can satisfy the required strength can be obtained.
[0036]
Here, for reference, a joint surface in the case where it is assumed that leakage has occurred in the airtightness test after temporary welding, that is, the main welding is performed following the temporary welding in FIG. 9 is a schematic cross-sectional view shown in FIG. As apparent from the figure, although the formation of a compatible layer 14 in contact the bulging portion 13 to the joint flange portion 5a serving as a counterpart is observed, to the gap G exceeds the allowable range G ₀ Compared with FIG. 1 (B), the penetration depth between the joint flange portions 4a and 5a is insufficient, and the required welding strength cannot be obtained.
[0037]
Furthermore, the joining flange portion 4a, in a case where the gap G 5a each other exceeds the allowable range G _0, and the laser energy dose required to achieve a welding strength that is suddenly required without a temporary weld ( Assume that the main welding is performed under a laser output level of 75 W, for example, as described above. In this case, since the state of the joint surface 9 as the welded portion is expected to be substantially the same as that in FIG. 9B, it is required when an airtightness test is performed after the main welding. However, there is a possibility that the product is determined to be a regular product satisfying the required welding strength, assuming that there is no leakage despite not satisfying the welding strength.
[0038]
Here, in the above embodiment, the laser output itself is changed as a method of changing the laser energy dosage between the temporary welding and the main welding. However, in addition to this, for example, the laser beam 6 at the time of laser welding is changed. The same effect can be obtained by changing the relative moving speed between the resin part 1 and the distance between the laser head 7 shown in FIG. 4B and the bonding surface 9 as the laser irradiation part. It is done.
[0039]
As described above, according to the present embodiment, on the premise that laser welding is performed in two steps of temporary welding and main welding, an airtightness test is performed between the temporary welding and main welding, so that the joining flange Production of the intake manifold 1 that cannot satisfy the required welding strength due to the excessive gap G between the portions 4a and 5a can be eliminated in advance.
[Brief description of the drawings]
1A and 1B are views showing a manufacturing process of the intake manifold shown in FIG. 2 as a preferred embodiment of the present invention, in which FIG. 1A is an enlarged cross-sectional view of a joint flange portion after temporary welding, and FIG. The expanded sectional view of a joining flange part.
FIGS. 2A and 2B are diagrams schematically showing a resin intake manifold as an example of a resin component, wherein FIG. 2A is a plan view thereof, FIG. 2B is a side view thereof, and FIG. 2C is a left side of FIG. FIG.
3 is an exploded view of the intake manifold shown in FIG. 2. FIG.
4A is an explanatory plan view of a laser welding apparatus that performs laser welding shown in FIG. 1, and FIG. 4B is an explanatory side view of the laser welding apparatus.
FIG. 5 is an explanatory diagram of the entire structure of a laser welding apparatus.
6 is an enlarged cross-sectional view showing an ideal welding state between the joining flange portions shown in FIG. 1; FIG.
7 is a characteristic diagram showing the relationship between the gap between the joining flange portions shown in FIG. 1 and the welding strength. FIG.
FIG. 8 is a flowchart showing an overall procedure including temporary welding, main welding, and an airtightness test as a preferred embodiment of the present invention.
9 (A) and 9 (B) are enlarged cross-sectional views when the gap between the joining flange portions exceeds the allowable range in the welding configuration of FIG. 1;
[Explanation of symbols]
1 ... Intake manifold (resin parts)
4 ... Half parts (resin members)
4a ... Joint flange 5 ... Half part (resin member)
5a ... Joining flange 6 ... Laser light 7 ... Laser head 9 ... Joining surface 12 ... Leak tester (airtightness test means)
G: Gap between joint flanges G ₀ ... Allowable range of gap

Claims (5)

After joining the flange portions formed in advance as welding margins to one resin member that transmits laser light and the other resin member that absorbs laser light, laser is applied from the side of the joint flange portion of one resin member. A laser welding method for resin parts integrated by irradiating light and welding resin members together,
Laser welding is performed in two steps, a temporary welding process and a main welding process.
After the temporary welding and before the main welding, perform the airtightness test of the resin parts,
The laser welding method for resin parts, wherein the main welding is performed only for resin parts for which the result of the airtightness test is appropriate. The method of laser welding of resin parts according to claim 1, wherein the temporary welding is performed with a dose of laser energy smaller than that during the main welding. While the above temporary welding is performed with a laser energy dosage less than the laser energy dosage required to obtain the required welding strength,
3. The laser welding method for resin parts according to claim 2, wherein the welding is performed with a laser energy dose required to obtain a required welding strength. The change in the laser energy dosage between the temporary welding and the main welding is a change in at least one of the laser output, the relative movement speed between the resin member and the laser beam, and the distance between the laser head and the laser irradiation site. The laser welding method for resin parts according to claim 2 or 3, wherein: After joining the flange portions formed in advance as welding margins to one resin member that transmits laser light and the other resin member that absorbs laser light, laser is applied from the side of the joint flange portion of one resin member. A laser welding device for resin parts, which is made by irradiating light to weld and integrate resin members,
Airtightness that performs the airtightness test while maintaining the positioning clamp state between the resin members, apart from the means for relatively moving and moving the resin members and the laser beam after positioning and clamping the two resin members. A laser welding apparatus for resin parts, comprising a test means.

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