Welding method of temperature controller

Abstract

To provide a welding method of a temperature controller capable of suppressing distortion after welding an aluminum-containing plate material by a superposed laser beam.SOLUTION: A welding method of a temperature controller includes, in the following order: a fixing step of superposing aluminum-containing plate materials P and fixing the aluminum-containing plate materials P by a jig G; a pre-heating step of raising a pair of the aluminum-containing plate materials P in a superposed state and the jig G to a preset pre-heating temperature; and a welding step S3 of irradiating one outer surface of the pair of aluminum-containing plate materials P in a heated state with a laser beam LB to weld the same.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for welding a temperature regulator. [Background technology]

[0002] Patent Document 1 describes a manufacturing method for a temperature regulator (referred to as a cooling plate in the document) in which two plate-shaped metal parts are joined by welding with laser light.

[0003] This patent document discloses that in order to reduce heat input during welding, intermittent welding is performed, thereby suppressing distortion due to heat within an acceptable range.

[0004] Patent Document 1 also discloses that by using a clamp fixture to fix the metal parts to be welded, distortion of the metal parts due to heat can be avoided and the clamp fixture can dissipate heat. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2020-510534 Summary of the Invention [Problem to be solved by the invention]

[0006] The welding method described in Patent Document 1 discloses that intermittent welding is used to suppress distortion due to heat, and also describes that deformation of metal parts due to clamp fixtures is avoided.

[0007] However, for example, when overlapping aluminum metal plates are welded using laser light, there is a large temperature difference between the areas of the metal plates that are not irradiated with the laser light and the areas that are irradiated with the laser light, which can lead to distortion of the metal plates.

[0008] Such distortion is difficult to avoid even by performing intermittent welding as in the technique described in Patent Document 1, and can also be said to be difficult to avoid with a clamp fixture having the structure described in Patent Document 1.

[0009] For these reasons, there is a demand for a welding method for a temperature regulator that can suppress distortion after overlapping aluminum-containing plate materials and welding them with a laser beam. [Means for solving the problem]

[0010] A characteristic feature of the welding method for a temperature regulator according to the present invention is that it is a welding method for a temperature regulator in which a pair of aluminum-containing plate materials are joined in an overlapping state to form a flow path space for flowing a fluid for regulating battery temperature, and includes a fixing step of overlapping the aluminum-containing plate materials and fixing the aluminum-containing plate materials with a jig, a preheating step of raising the temperature of the pair of aluminum-containing plate materials and the jig in an overlapping state to a set preheating temperature, and a welding step of irradiating an outer surface of one of the pair of aluminum-containing plate materials in a heated state with laser light to weld it, in this order.

[0011] According to this configuration, when welding is performed, the aluminum-containing plate materials are overlapped and fixed by a jig (fixing step), and the overlapped aluminum-containing plate materials and the jig are heated to a set preheat temperature (preheating step). Next, the heated aluminum-containing plate materials are welded by irradiating a laser beam (welding step). In this welding step, the temperature difference between the aluminum-containing plate materials whose temperature has already increased and the parts of the aluminum-containing plate materials whose temperature has increased by irradiating a laser beam is reduced, so that the difference in the amount of shrinkage during solidification shrinkage can be reduced and distortion can be suppressed. In addition, since the overlapped aluminum-containing plate materials are fixed by a jig, it is possible to suppress distortion even if a situation that causes distortion in the aluminum-containing plate materials occurs. In this way, a welding method of a temperature regulator that can suppress distortion after overlapping aluminum-containing plate materials and welding them with a laser beam is achieved. [Brief description of the drawings]

[0012] [Figure 1] FIG. 4 is a perspective view of the plate material and the jig in a fixing step of the welding method. [Diagram 2] FIG. 2 is a cross-sectional view of a heating furnace in a preheating step of a welding method. [Diagram 3] FIG. 2 is a side view of the welding device in a welding step of the welding method. [Figure 4] FIG. 2 is a cross-sectional view of a temperature regulator with a battery mounted thereon. [Diagram 5] FIG. 13 is a cross-sectional view showing the contraction force along the scanning direction for the welded area. [Figure 6] FIG. 11 is a cross-sectional view showing a contraction force acting from a position sandwiching the welded region. [Figure 7] 11 is a diagram showing a natural heat dissipation graph and a limited heat dissipation graph in a heat dissipation process. FIG. [Figure 8] FIG. 1 illustrates a welding sequence for four linear welded areas. [Figure 9] FIG. 13 is a graph showing the relationship between the amount of warping and cracking versus the preheating temperature. [Figure 10] 13 is a graph showing the amount of warping versus preheating temperature for each laser beam output. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a "welding method for a temperature regulator" according to the present invention will be described with reference to the drawings. In this embodiment, as an example of a welding method for a temperature regulator A, a method is described in which aluminum-containing plate materials P having a shape shown in the drawings are overlapped, fixed with a jig G, and welded with a laser beam LB from a laser source 11 of a welding device W to join the aluminum-containing plate materials P. This embodiment is one form of a welding method for a temperature regulator A, and is not limited to this embodiment, and various modifications are possible within the scope of the gist of the invention.

[0014] [Basic configuration] As shown in Figures 1 and 4, a press-formed aluminum-containing first plate material P1 (one example of an aluminum-containing plate material P) and a flat aluminum-containing second plate material P2 (one example of an aluminum-containing plate material P) are overlapped and welded with a laser beam LB (hereinafter sometimes referred to as laser welding: see Figures 3 and 5) to form a temperature regulator A. The aluminum-containing plate material P is a plate material containing 95% or more by weight of aluminum, and examples of such alloys include pure aluminum, Al-Cu alloys, Al-Mn alloys, Al-Mg alloys, Al-Mg-Si alloys, and Al-Zn-Mg alloys.

[0015] Temperature regulator A manages the temperature of battery B in vehicles that can run on power supplied from battery B, such as hybrid vehicles (HVs), fuel cell vehicles (FCVs), and electric vehicles (EVs).

[0016] As shown in Fig. 4, the temperature regulator A is disposed at a position where a flow path space AC for a heat exchange fluid is formed and where the temperature regulator A is in contact with the battery B. The temperature regulator A functions to maintain the battery B at an appropriate temperature by flowing a heat exchange fluid with a controlled temperature through the multiple flow path spaces AC.

[0017] Incidentally, the temperature regulator A shown in FIG. 1 shows a configuration of a plurality of flow path spaces AC, but it may be configured, for example, such that the heat exchange fluid supplied from a single supply port is branched and supplied to a plurality of flow path spaces AC, and after regulating the temperature of the battery B, the flow paths are joined together and discharged from a single discharge port.

[0018] As shown in FIG. 1 and FIG. 4, the first plate P1 is formed with a plurality of protrusions Pa in parallel by pressing. The second plate P2 is a flat plate. The temperature regulator A is formed by stacking the first plate P1 and the second plate P2, and welding the contact portion between the first plate P1 and the second plate P2 using a laser beam LB. By this welding, the temperature regulator A creates a flow path space AC between the protrusions Pa of the first plate P1 and the second plate P2. In the embodiment, a flat plate-shaped material is used for the second plate P2, but the second plate P2 may also be formed with a plurality of protrusions Pa, similar to the first plate P1.

[0019] In addition, in the temperature regulator A, a portion where the second plate material P2 is exposed (lower side in FIG. 4) is referred to as a bottom surface, and a portion where the protruding portion Pa is formed in the first plate material P1 (upper side in FIG. 4) is referred to as an upper surface.

[0020] [Challenges in laser welding] The problem with welding is that when two overlapping aluminum-containing plate materials P are laser welded, warping or cracking can occur due to the difference in the amount of shrinkage that accompanies solidification shrinkage.

[0021] The welded area Wa shown in Fig. 5 is a cross section seen from a direction perpendicular to the scanning direction (length direction X). The welded area Wa shown in Fig. 6 is a cross section seen from a direction perpendicular to the scanning direction (width direction Y).

[0022] As shown in Figures 5 and 6, the phenomena of warping and cracking occur when welding is performed by irradiating laser light LB onto the upper surface (outer surface) of the upper aluminum-containing plate material P, and when the welded area Wa created by this welding solidifies and shrinks, due to the difference in the amount of shrinkage between the aluminum-containing plate material P and the amount of shrinkage of the welded area Wa.

[0023] The solidification shrinkage in the direction along the scanning direction (length direction X) occurs because, although the temperature of the welded area Wa rises due to welding, the temperature of the second plate material P2 is not as high as that of the welded area Wa. For this reason, a shrinkage force acts in the direction indicated by the arrow F1 at both ends of the welded area Wa in the scanning direction as shown in Fig. 5, resulting in warping in which both ends in the scanning direction are lifted.

[0024] In addition, the solidification shrinkage in the direction perpendicular to the scanning direction is caused by the fact that although the temperature of the welded area Wa rises due to welding, the temperature of the two areas of the first plate material P1 sandwiching the welded area Wa is not as high as that of the welded area Wa. This leads to warping and distortion in the area perpendicular to the scanning direction, with both sides lifting in the direction indicated by the arrows F2, as shown in FIG. 6.

[0025] The amount of warping due to the force indicated by the arrow F1 increases as the temperature difference between the welding area Wa and the second plate material P2 increases. In contrast, the amount of warping or distortion due to the contraction force indicated by the arrow F2 increases as the temperature difference between the welding area Wa and the first plate material P1 increases.

[0026] In order to solve these problems, the welding method for a temperature regulator, which will be described next, involves stacking a first plate material P1 and a second plate material P2, preheating them, and then performing laser welding at an elevated temperature, thereby suppressing warping, distortion, and cracking.

[0027] [Welding method for temperature controller] The "temperature regulator welding method" is composed of a fixing step (S1) of overlapping a first plate material P1 and a second plate material P2 and fixing them with a jig G, as shown in FIG. 1, a preheating step (S2) of raising the overlapping aluminum-containing plate material P and the jig G to a preheating temperature, as shown in FIG. 2, and a welding step (S3) of welding the first plate material P1 and the second plate material P2 in a heated state with them fixed to the jig G using laser light LB from a laser light source 11 of a welding device W, as shown in FIG. 3.

[0028] Furthermore, when manufacturing the temperature regulator A, after the welding step (S3), assembly steps are performed, such as dissipating heat, removing the jig G, and attaching plugs and tubes communicating with the flow passage space AC.

[0029] 1, the first plate material P1 and the second plate material P2 have predetermined sizes in the length direction X and width direction Y. The jig G has a plate-like frame portion 1 that is slightly longer than the dimensions of the first plate material P1 and the second plate material P2 in the length direction X and is approximately equal in the width direction Y, and has clamp portions 3 on fixing portions 2 at both ends of the frame portion 1 in the length direction X.

[0030] [Temperature controller welding method: fixing step] In the fixing step (S1), the first plate material P1 and the second plate material P2 are overlapped and their both ends, which are the peripheral parts in the length direction X, are clamped and fixed by the clamp unit 3. This fixation maintains the first plate material P1 and the second plate material P2 in contact with each other, and reaches a state in which the bottom surface of the first plate material P1 is pressed against the surface of the frame unit 1. In this fixing step (S1), the locations where the clamp unit 3 clamps and fixes the first plate material P1 and the second plate material P2 are not limited to the peripheral parts of the first plate material P1 and the second plate material P2, but may be the entire periphery of the plate materials, a location in the center of the plate materials where a flow path is formed, or the peripheral parts in the width direction Y of the plate materials.

[0031] The jig G has fixing parts 2 at both ends in the longitudinal direction X, which are positioned higher than the surface of the frame part 1. The clamp part 3 has a fixing plate 3a and a screw-type fastener 3b that is inserted into a through hole of the fixing plate 3a and screws into the female screw part 2a at the end of the fixing part 2.

[0032] The configuration of the clamp unit 3 is not limited to the configuration shown in FIG. 1, and it is possible to use a configuration that creates a crimped state using the biasing force of a spring, or that maintains the crimped state using a turnbuckle, etc.

[0033] [Welding method for temperature controller: preheating step] In the preheating step (S2), the first plate material P1 and the second plate material P2 fixed to a jig G are placed in a heating space 5S of the heating furnace 5 as shown in Fig. 2, and the temperature is increased to a preheating temperature in the heating space 5S. The preheating temperature is about 300°C, and the first plate material P1, the second plate material P2, and the jig G are removed from the heating furnace 5 after they have reached the preheating temperature.

[0034] The heating furnace 5 is assumed to be configured to heat the heating space 5S by an electric heater, but may be configured to increase the temperature of the heating space 5S by supplying combustion gas obtained by burning city gas, for example.

[0035] [Welding method for temperature controller: Welding steps] As shown in FIG. 3, the welding device W includes an infrared laser light source 11, a guide rail 12 that linearly guides the laser light source 11 along the scanning direction, a belt-type moving mechanism 13 that moves the laser light source 11 along the guide rail 12, and a scanning motor 14 that drives the moving mechanism 13.

[0036] This welding device W has a scanning motor 14, a beam control unit 15 that controls the laser light LB of the laser light source 11, and a control device 16 that controls these.

[0037] The welding device W also includes a support plate 17 that supports the jig G, a plurality of drive rollers 18 that move the support plate 17 in a shift direction (corresponding to the width direction Y) perpendicular to the scanning direction (corresponding to the length direction X) of the laser light source 11, and a shift motor 19 that controls the rotation of the drive rollers 18. The shift motor 19 is controlled by the control device 16 described above.

[0038] In the welding step (S3), a jig G holding the first plate material P1 and the second plate material P2 is placed on the support plate 17, and while the first plate material P1 and the second plate material P2 are maintained at a preheating temperature, the laser light source 11 is moved in the longitudinal direction X at a set speed, and as shown in FIG. 5, the first plate material P1 and the second plate material P2 are welded together by irradiating them with laser light LB during this movement.

[0039] The preheat temperature of 300° C. set in the preheat step (S2) described above is a temperature that satisfactorily suppresses warping in the welding step (S3).

[0040] In addition, in laser welding, the welding position in the width direction Y can be changed by driving the shift motor 19, and for example, it is possible to form a plurality of welding areas Wa as shown in FIG.

[0041] In addition, the temperature may be corrected to increase the preheat temperature set in the preheat step (S2) taking into account the environmental temperature in the welding step (S3) and the amount of heat dissipation between the first plate material P1 and the second plate material P2 when transitioning from the preheat step (S2) to the welding step (S3).

[0042] [Effects of the embodiment] As explained above in the section "Issues in Laser Welding," the solidification and shrinkage of the welded area Wa acts in the direction indicated by the arrow F1 in FIG. 5 (the direction that coincides with the scanning direction of the laser light LB) and in the direction indicated by the arrow F2 in FIG. 6 (the direction perpendicular to the scanning direction of the laser light LB).

[0043] In contrast, in the [Welding method for temperature regulators], the first plate material P1 and the second plate material P2, whose temperatures have been increased in the preheating step (S2), are welded by irradiating them with laser light LB in the welding step (S3). This reduces the temperature difference between the welding area Wa and the second plate material P2, thereby reducing the amount of contraction acting in the direction of the arrow F1, suppressing the amount of warping and distortion, and preventing cracks.

[0044] Similarly, in the [temperature regulator welding method], both ends of the first plate material P1 and the second plate material P2 in the longitudinal direction X are fixed by a jig G, thereby suppressing warping through mechanical restraint.

[0045] Furthermore, in the [temperature regulator welding method], since the temperature of the first plate material P1 is raised to the preheat temperature by the preheating step (S2), even when welding is performed by irradiating the laser light LB, the temperature difference between the temperature of the welding area Wa and the temperature of the first plate material P1 is reduced, and as a result, the amount of contraction acting in the direction of the arrow F2 is reduced, and warping and distortion are suppressed.

[0046] The heat dissipation process following the welding step (S3) is a process of removing the aluminum-containing plate material P from the jig G after the temperature has dropped to a set temperature by heat dissipation. This set temperature is a temperature at which the worker can touch the aluminum-containing plate material P, and is assumed to be 50°C to 60°C. As shown in FIG. 7, this heat dissipation process can also achieve a relatively rapid temperature drop as shown in the natural heat dissipation graph Ta by adopting natural heat dissipation. However, it is desirable to suppress rapid cooling in the heat dissipation process, and for example, a slow temperature change is achieved as shown in the limited heat dissipation graph Tb by using a means for limiting the temperature drop in the heat dissipation environment.

[0047] The graph shown in FIG. 5 shows that a test piece of a high-strength aluminum alloy (an example of an aluminum-containing plate material P) having the size shown in FIG. 8 is used as the first plate material P1 and the second plate material P2, and the processing is performed in the order of a fixing step (S1), a preheating step (S2), and a welding step (S3), thereby enabling the reduction of warpage distortion.

[0048] 8, the test piece has a length dimension Lx in the length direction X of 230 mm, a width dimension Ly in the width direction Y of 130 mm, and a thickness of 1.2 mm. Also, the weld length Lw in the scanning direction of the laser light LB is 210 mm.

[0049] It is also assumed that this test piece will be laser-welded in four linear weld areas Wa in the order shown by (1) to (4) in Fig. 8. By performing laser welding in this order, it is possible to suppress the increase in warping and distortion overall.

[0050] 9 shows the relationship between the preheat temperature, the amount of warping of the test piece, and the number of cracks at the welded portion when laser welding was performed at a plurality of preheat temperatures. The amount of warping is the amount of lift at both ends in the longitudinal direction X when the test piece is placed on a horizontal surface plate after laser welding. The number of cracks can be determined, for example, by applying liquid to the outer surface of the welded area Wa and judging gas leakage from bubbles in the liquid when the gas pressure in the flow path space AC is increased.

[0051] As shown in Figure 9, the amount of warping decreases as the preheating temperature increases, and it can be seen that the amount of warping is at a minimum when the preheating temperature is 300°C or higher. It can also be seen that the number of cracks decreases as the preheating temperature increases, and the number of cracks drops to zero when the preheating temperature is 120°C or higher.

[0052] Thus, the effectiveness of setting the preheat temperature to 120°C or higher has been proven. On the other hand, the preheat temperature that reduces the amount of warping to zero is 300°C or higher, but if it exceeds 400°C, the aluminum-containing plate material P softens and the strength decreases, so it is preferably 400°C or lower. Thus, the preheat temperature range that can simultaneously suppress the amount of warping and prevent weld cracks is 120°C to 400°C, and more preferably 200°C to 300°C.

[0053] 10 shows the relationship between the preheat temperature and the warpage of test pieces when high-strength aluminum alloy test pieces as the first plate material P1 and the second plate material P2 are welded at a number of preheat temperatures using the laser light source 11. The figure also shows the relationship between the preheat temperature and the warpage of the test pieces when welding is performed using two types of laser light sources 11 with different outputs.

[0054] Fig. 10 shows the amount of warping when welding is performed using laser beams LB with different powers. As shown in the figure, it can be seen that even when laser beams LB with different powers are used, the amount of warping is the smallest when the preheating temperature reaches 300°C.

[0055] [Another embodiment] The present invention may be configured as follows other than the above-described embodiment (common numbers and symbols as in the embodiment are used to designate components having the same functions as in the embodiment).

[0056] (a) The welding device W is configured to include a laser light source 11 at the tip of a robot hand. In the welding device W of this alternative embodiment (a), the operation of the robot hand enables welding not only to linear welding areas Wa, but also to curved welding areas Wa.

[0057] (b) In the preheating step (S2), it is also possible to adopt an appropriate preheating temperature within the range of 120°C to 400°C taking into consideration the thermal expansion coefficient of the aluminum-containing plate material P, the melting point of the aluminum-containing plate material P, etc.

[0058] This makes it possible to set an optimum preheating temperature in accordance with the properties of the aluminum-containing plate material P that constitutes the temperature regulator A, thereby making it possible to suppress warping.

[0059] (c) A welding method of a temperature regulator is configured such that a work location for a fixing step (S1) in which the first plate material P1 and the second plate material P2 are restrained against the jig G is set during the transport path by the conveyor belt, a heating location is set downstream of this work location in the transport direction by the conveyor belt to enable processing in a preheating step (S2) in which the jig G, the first plate material P1 and the second plate material P2 are supplied to a heating furnace 5, and a processing location is set downstream of this heating location in the transport direction by the conveyor belt to enable welding in a welding step (S3).

[0060] In this alternative embodiment (c), the fixing step (S1), the preheating step (S2), and the welding step (S3) can be partially automated, enabling efficient work.

[0061] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided that no contradiction arises. Furthermore, the embodiments disclosed in this specification are merely examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention.

[0062] In the above-described embodiment, the following configurations are envisaged. (1) A welding method for a temperature regulator A in which a pair of aluminum-containing plate materials P are joined in an overlapping state to form a flow path space AC for flowing a fluid for regulating the temperature of a battery B, the method for welding a temperature regulator A comprising the steps of: a fixing step S1 in which the aluminum-containing plate materials P are overlapped and fixed with a jig G; a preheating step S2 in which the pair of overlapping aluminum-containing plate materials P and the jig G are heated to a set preheat temperature; and a welding step S3 in which a laser beam LB is irradiated to an outer surface of one of the pair of aluminum-containing plate materials P in a heated state to weld it, in this order.

[0063] According to this configuration, when welding is performed, the aluminum-containing plate material P is overlapped and fixed by the jig G (fixing step S1), and the overlapped aluminum-containing plate material P and the jig G are heated to a set preheat temperature (preheating step S2). Next, the heated aluminum-containing plate material P is welded by the laser light LB (welding step S3), thereby reducing the temperature difference between the aluminum-containing plate material P whose temperature has already been increased and the welded area Wa of the aluminum-containing plate material P whose temperature has been increased by irradiation with the laser light LB, thereby reducing the difference in the amount of shrinkage due to solidification shrinkage and suppressing warping and distortion. In addition, since the overlapped aluminum-containing plate material P is fixed by the jig G, warping and distortion can be suppressed even in a situation where distortion is caused in the aluminum-containing plate material P.

[0064] In the welding method of temperature regulator A in (2)(1), it is preferable to dissipate heat from the aluminum-containing plate material P welded in welding step S3 and remove the jig G after the temperature has dropped to the set temperature (50°C to 60°C as described above).

[0065] According to this configuration, the aluminum-containing plate material P is separated from the jig G after the shape of the aluminum-containing plate material P has stabilized due to a temperature drop caused by heat dissipation, so that the aluminum-containing plate material P will not be deformed even if an external force is applied, for example.

[0066] (3) In the welding method using temperature regulator A of (1) or (2), it is preferable that the preheating temperature is set to 120°C or higher and 400°C or lower.

[0067] According to this, from the wide temperature range from 120°C to 400°C, it is possible to select a temperature at which distortion is unlikely to occur, for example, based on the relationship between the temperature and thermal expansion coefficient of the aluminum-containing plate material P used in the temperature regulator A. [Industrial Applicability]

[0068] The present invention can be used in a welding method for a temperature regulator. [Explanation of symbols]

[0069] A: temperature controller, AC: flow path space, B: battery, G: jig, LB: laser light, P: aluminum-containing plate material, S1: fixing step, S2: preheating step, S3: welding step

Claims

1. A method for welding a temperature regulator in which a pair of aluminum-containing plate materials are joined in an overlapping state to form a flow path space for flowing a fluid for regulating the temperature of a battery, comprising the steps of: A fixing step of overlapping the aluminum-containing plate material and fixing the aluminum-containing plate material with a jig; A preheating step of heating the pair of aluminum-containing plate materials and the jig in a superposed state to a set preheating temperature; a welding step of irradiating a laser beam onto an outer surface of one of the pair of aluminum-containing plate materials in a heated state to weld the plate materials, in this order.

2. The method for welding a temperature regulator according to claim 1 , further comprising the step of: releasing heat from the aluminum-containing plate material welded in the welding step, and removing the jig after the temperature has dropped to a set temperature.

3. 3. The method for welding a temperature regulator according to claim 1, wherein the preheating temperature is set to 120° C. or higher and 400° C. or lower.

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