A process for welding a diaphragm to a battery case

Abstract

The application discloses a kind of based on harmonica profile battery shell flow channel partition welding process, comprising the following steps: the harmonica profile to be welded is fixed on workbench, according to design machine adds the rib position of profile, and ensure that the rib position is without residue after machining;According to design, partition structure is placed in the position to be welded and carries out accurate positioning, ensure that the upper and lower sides of partition structure and flow channel are closely matched;Using the stirring friction welding head with a penetration depth of not less than 2mm to weld the partition structure, so that the process hole formed after welding is retained in the middle of the partition structure;After welding the partition structure, the profile is subjected to a repair welding process hole, and the two end plugs are welded to obtain an initial product of the shell;The initial product of the shell is subjected to airtightness test, and if the test is passed, the finished product of the shell is obtained, otherwise, the leaking position is repaired.The significant effect is that the first-time pass rate of airtightness test of the product is greatly improved, and the thermal deformation is not obvious.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle parts processing technology, specifically to a battery casing flow channel separation welding process based on harmonica-shaped profiles. Background Technology

[0002] Currently, automotive power batteries are basically composed of the following systems: battery modules, battery management system, thermal management system, and electrical and mechanical systems. Among these, the battery thermal management system is a management system designed to ensure the battery system operates within a suitable temperature range. It mainly consists of components such as the casing, heat transfer medium, and monitoring equipment. The cooling performance of the power battery directly affects its efficiency, as well as its lifespan and safety. Currently, there are four common cooling methods: natural cooling, forced air cooling, liquid cooling, and direct cooling.

[0003] When liquid cooling is used, in order to reduce the weight and volume of the liquid cooling plate, Chinese patent CN207282666U discloses an ultra-thin friction stir welded aluminum alloy liquid cooling plate. This patent forms a flow channel for coolant flow inside the battery casing by extruding profiles. The traditional processing technology for battery casings based on this liquid cooling plate is as follows: extruded profile units are friction welded into harmonica-shaped large flat plates to form the main body of the casing. Then, some ribs are removed by machining to form the required shape. Afterwards, welded partitions are made inside the profile cavity as needed to allow the coolant to flow in a specified direction.

[0004] However, after using friction welding to weld the partitions, the process holes that were friction welded need to be repaired using argon arc welding. But argon arc welding can cause thermal deformation at the repair location, leading to leaks at the repair location during airtightness testing, requiring multiple repair welds. Multiple repair welds further exacerbate thermal deformation and may even render the entire board unusable. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a welding process for the flow channel separation of battery casing based on harmonica-shaped profile. By improving the welding process, the first pass rate of airtightness test after welding process hole is effectively improved, and the thermal deformation caused by welding is effectively controlled.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A battery casing flow channel separation welding process based on a harmonica-shaped profile, the key of which includes the following steps:

[0008] Step 1: Fix the harmonica-shaped profile to be welded on the workbench, machine remove the ribs of the profile according to the design, and ensure that there are no machine-made ribs left.

[0009] Step 2: Place the partition structure in the welding position according to the design and accurately position it to ensure that the partition structure fits tightly with the upper and lower sides of the flow channel.

[0010] Step 3: Use a friction stir welding head with a penetration depth of not less than 2mm to weld the partition structure. When welding, the friction stir welding head welds from one end of the partition structure to the other end, and after reaching the other end of the partition structure, it turns around and welds to the middle of the partition structure, so that the process hole formed after welding is retained in the middle of the partition structure.

[0011] Step 4: After welding the partition structure, perform additional welding on the process holes and weld the plugs at both ends of the profile to obtain the initial finished shell.

[0012] Step 5: Conduct an airtightness test on the initial shell product. If the test passes, the finished shell product is obtained; otherwise, the leaking area is repaired by welding.

[0013] Furthermore, the harmonica-shaped profile is made by welding together several extruded profile units with identical structures.

[0014] Furthermore, after the extruded profile unit is welded, the gap between the welded positions is less than 0.5 mm, the height difference is less than 0.5 mm, and welding is performed on both the front and back sides of the extruded profile unit.

[0015] Furthermore, the welding parameters for the extruded profiles to be welded together to form a harmonica-shaped profile are as follows: the feed speed of the friction welding stirring head is 800-1200 mm / min, the rotation speed is 1300-1600 r / min, and the flatness after welding is less than 2 mm.

[0016] Furthermore, in step 4, the shoulder width of the friction stir welding head and the width of the partition structure satisfy the following relationship:

[0017] G = Z * 2 - 2,

[0018] Where G is the width of the partition structure and Z is the shoulder width of the friction stir welding drill bit.

[0019] Furthermore, the welding parameters of the friction stir welding head in step 4 are: feed speed of 800-1200 mm / min and rotation speed of 1300-1600 r / min.

[0020] The significant effects of this invention are:

[0021] This invention widens the partition structure and uses friction welding to weld from one end of the partition to the other. After reaching the end of the partition structure, it turns around and welds to the middle of the partition structure, so that the friction welding process hole is located in the middle of the partition structure. At this position, the partition structure and the harmonica board profile are friction welded together, which greatly improves the first pass rate of the airtightness test after welding the process hole, and the thermal deformation is not obvious. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method of the present invention;

[0023] Figure 2 This is a structural schematic diagram of the harmonica-shaped profile;

[0024] Figure 3 This is the front view of the harmonica-shaped profile;

[0025] Figure 4 This is the left view of the harmonica-shaped profile.

[0026] Figure 5 yes Figure 4 AA section view;

[0027] Figure 6 This is a schematic diagram of the welding path for the partition structure. Detailed Implementation

[0028] The specific embodiments and working principles of the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] like Figure 1 As shown, a battery casing flow channel separation welding process based on a harmonica-shaped profile includes the following steps:

[0030] Step 1: Fix the harmonica-shaped profile 10 to be welded on the workbench, machine remove the ribs of the profile according to the design, and ensure that there are no machine-made ribs left.

[0031] Step 2: Place the partition structure 20 in the welding position according to the design and accurately position it to ensure a tight fit between the partition structure 20 and the upper and lower sides of the flow channel. Figures 2-5 As shown;

[0032] Step 3: Use a friction stir welding head with a penetration depth of not less than 2mm to weld the partition structure 20. During welding, the friction stir welding head welds from one end of the partition structure 20 to the other end, and after reaching the other end of the partition structure 20, it turns around and welds to the middle of the partition structure 20. The welding path is as follows: Figure 6 As shown, this is to ensure that the process hole formed after welding remains in the middle of the partition structure 20;

[0033] Step 4: After welding the partition structure 20, perform additional welding on the process holes and weld the end caps 30 to obtain the initial finished shell.

[0034] In this embodiment, the shoulder width of the friction stir welding head in step 4 and the width of the partition structure 20 satisfy the following relationship:

[0035] G = Z * 2 - 2,

[0036] Where G is the width of the partition structure 20, and Z is the shoulder width of the friction stir welding drill bit.

[0037] During welding, the welding parameters for the friction stir welding head are: feed speed of 800-1200 mm / min and rotation speed of 1300-1600 r / min.

[0038] Step 5: Conduct an airtightness test on the initial shell product. If the test passes, the finished shell product is obtained; otherwise, the leaking area is repaired by welding.

[0039] In this example, the harmonica-shaped profile 10 is formed by welding together several extruded profile units 11 with identical structures, such as... Figures 2-5 As shown, after the extruded profile unit 11 is welded, the gap between the welding positions is less than 0.5 mm, the height difference is less than 0.5 mm, and welding is performed on both the front and back sides of the extruded profile unit 11. The welding parameters when the extruded profile unit 11 is welded together to form a harmonica-shaped profile 10 are: the feed speed of the friction welding stirring head is 800-1200 mm / min, the rotation speed is 1300-1600 r / min, and the flatness after welding is less than 2 mm.

[0040] In this embodiment, the partition structure 20 is widened, and friction welding is used to weld from one end of the partition to the other. After reaching the end of the partition structure 20, it is turned around and welded to the middle of the partition structure 20, so that the friction welding process hole is located in the middle of the partition structure 20. At this position, the partition structure 20 and the harmonica board profile have been friction welded into one piece, thereby increasing the airtightness first-pass rate of the partition position after welding the process hole from 10% to 95%, and the thermal deformation is not obvious.

[0041] The technical solution provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A battery casing flow channel separation welding process based on a harmonica-shaped profile, characterized in that, Includes the following steps: Step 1: Fix the harmonica-shaped profile to be welded on the workbench, machine remove the ribs of the profile according to the design, and ensure that there are no machine-made ribs left. Step 2: Place the partition structure in the welding position according to the design and accurately position it to ensure that the partition structure fits tightly with the upper and lower sides of the flow channel. Step 3: Use a friction stir welding head with a penetration depth of not less than 2mm to weld the partition structure. During welding, the friction stir welding head welds from one end of the partition structure to the other end, and then turns around to weld to the middle of the partition structure after reaching the other end, so that the process hole formed after welding is retained in the middle of the partition structure. The shoulder width of the friction stir welding head and the width of the partition structure satisfy the following relationship: G=Z*2-2, where G is the width of the partition structure and Z is the shoulder width of the friction stir welding head. Step 4: After welding the partition structure, perform additional welding on the process holes and weld the plugs at both ends of the profile to obtain the initial finished shell. Step 5: Conduct an airtightness test on the initial shell product. If the test passes, the finished shell product is obtained; otherwise, the leaking area is repaired by welding.

2. The battery casing flow channel separation welding process based on harmonica-shaped profile according to claim 1, characterized in that: The harmonica-shaped profile is made by welding together several extruded profile units with the same structure.

3. The battery casing flow channel separation welding process based on harmonica-shaped profile according to claim 2, characterized in that: After the extruded profile unit is welded, the gap between the welded positions is less than 0.5 mm, the height difference is less than 0.5 mm, and welding is performed on both the front and back sides of the extruded profile unit.

4. The battery casing flow channel separation welding process based on a harmonica-shaped profile according to claim 2 or 3, characterized in that: The welding parameters for forming a harmonica-shaped profile by welding the extruded profiles together are as follows: the feed speed of the friction welding stirring head is 800-1200 mm / min, the rotation speed is 1300-1600 r / min, and the flatness after welding is less than 2 mm.

5. The battery casing flow channel separation welding process based on harmonica-shaped profile according to claim 1, characterized in that: The welding parameters for the friction stir welding head in step 4 are: feed speed of 800-1200 mm / min and rotation speed of 1300-1600 r / min.

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