A method for preparing a motor housing by using an extrusion thickening and deep drawing forming process

Abstract

The present invention belongs to the technical field of motor shell preparation, and discloses a method for preparing a motor shell by using an extrusion thickening and deep drawing process, so that the aluminum alloy motor shell will not be broken during the forming process, and the production efficiency and qualified rate of the aluminum alloy motor shell are improved. The method includes: step 10, through experimental measurement and simulation analysis methods, the aluminum alloy plate drawing coefficient for setting each process is obtained; step 20, according to the aluminum alloy plate drawing coefficient, the aluminum alloy plate is deep drawn to obtain a first motor shell; the height of the first motor shell is H; the first motor shell includes an upper motor shell and a lower motor shell; the upper motor shell is located above the lower motor shell, and the upper motor shell has a convex arc surface; step 30, using an extrusion process to reduce the diameter of the upper motor shell until the motor shell is obtained; during the extrusion process, the height of the upper motor shell and the height of the lower motor shell remain unchanged.

Description

Technical Field

[0001] The present invention relates to the technical field of motor casing preparation, and in particular to a method for preparing a motor casing by utilizing an extrusion thickening and deep drawing forming process. Background Art

[0002] With the continuous increase in the production and sales of new energy vehicles, the performance and quality requirements for motor housings are getting higher and higher. Aluminum alloy motor housings are widely used in motor manufacturing due to their advantages such as good thermal conductivity, light weight and corrosion resistance. However, aluminum alloy motor housings processed by die-casting are costly and inefficient, and are not suitable for mass production in the automotive industry. The traditional deep drawing process often has the problem of easy cracking when manufacturing aluminum alloy motor housings, which seriously affects the quality and performance of the motor housing.

[0003] The motor housing parts are stepped cylindrical parts. During the deep drawing process of the steel motor housing, the barrel depth is gradually increased and the barrel diameter is reduced by using the principle of constant volume. After multiple deep drawing processes, the motor housing with equal wall thickness is formed. However, when the same forming technology is used in aluminum plate forming, due to factors such as the small anisotropy coefficient of the aluminum plate thickness, low hardening index, low tensile strength, and low elongation, it will cause cracks during the deep drawing process, especially the small diameter of the barrel on the upper part of the motor housing, which is more prone to cracking during the deep drawing process. Summary of the invention

[0004] Technical problem: The technical problem to be solved by the present invention is to provide a method for preparing a motor shell by using an extrusion thickening and deep drawing forming process, so that the aluminum alloy motor shell will not crack during the forming process, thereby improving the production efficiency and qualified rate of the aluminum alloy motor shell.

[0005] Technical solution: To solve the above technical problems, the embodiment of the present invention provides a method for preparing a motor shell by using an extrusion thickening and deep drawing process, wherein the motor shell is made of an aluminum alloy, and the finally manufactured motor shell is a stepped cylindrical structure, comprising an upper cylinder and a lower cylinder connected to the upper cylinder, and the upper cylinder and the lower cylinder are coaxial; the height of the finally manufactured motor shell is H; the method comprises the following steps:

[0006] Step 10, obtaining the aluminum alloy sheet drawing coefficient for each process through experimental measurement and simulation analysis method;

[0007] Step 20, drawing the aluminum alloy plate according to the drawing coefficient of the aluminum alloy plate to obtain a first motor housing; the height of the first motor housing is H; the first motor housing includes an upper motor housing and a lower motor housing; the upper motor housing is located above the lower motor housing, and the upper motor housing has a convex arc surface;

[0008] Step 30, using an extrusion process to reduce the diameter of the upper motor housing until the motor housing is obtained; during the extrusion process, the height of the upper motor housing and the height of the lower motor housing remain unchanged;

[0009] In step 30, the thickness increased by the upper motor housing wall during extrusion is obtained according to formula (1):

[0010] △T=△V÷S Formula (1)

[0011] Among them, △T represents the increased thickness of the upper motor shell wall, △V represents the volume difference between the lower motor shell wall and the upper motor shell wall of the same height, and S represents the surface area of ​​the upper motor shell.

[0012] Preferably, in step 10, the first drawing coefficient of the aluminum alloy plate is 0.5-0.6, and the subsequent drawing coefficient is 0.8-0.9.

[0013] Preferably, in step 20, the aluminum alloy plate is deep drawn at least three times to obtain a first motor housing; the lower motor housing is a hollow cylinder; the upper motor housing is a hollow hemisphere; the lower motor housing and the upper motor housing are connected.

[0014] Preferably, in step 20, the aluminum alloy plate is deep drawn 4 to 5 times to obtain the first motor housing.

[0015] Preferably, in step 30, an extrusion process is performed using a forming die; the forming die is provided with a concave and convex die, and a gap between the concave and convex dies is the thickness of the cylinder wall of the upper motor housing during each extrusion process.

[0016] Preferably, in step 30, the upper motor housing is squeezed 7 to 8 times; each squeezing gradually reduces the diameter of the upper motor housing.

[0017] Preferably, in step 30, when the upper motor housing is extruded, the first drawing coefficient is 0.5-0.6, and the subsequent drawing coefficient is 0.8-0.9.

[0018] Preferably, in the motor housing obtained in step 30, the height of the upper cylinder is 10-12 mm, the inner diameter is 7-8 mm, and the outer diameter is 10.5-12 mm.

[0019] Preferably, in the motor housing obtained in step 30, the height of the lower cylinder is 50-60 mm, the inner diameter is 37-43 mm, and the outer diameter is 43-48 mm.

[0020] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial effects: a method for preparing a motor shell by utilizing an extrusion thickening and drawing forming process of the present invention, when drawing an aluminum alloy motor shell, the motor shell is gradually drawn according to a drawing coefficient, and a lower motor shell and an upper motor shell are formed by drawing; the upper motor shell is formed by a step-by-step extrusion method, and the upper motor shell is formed by extrusion, which does not increase the height of the upper motor shell, but only increases the wall thickness of the upper motor shell, so that the motor shell will not crack during the forming process, thereby improving the forming efficiency of the motor shell and the qualified rate of the formed motor shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flow chart of an embodiment of the present invention;

[0022] Figure 2 is a structural diagram of the first motor housing made in step 20 in an embodiment of the present invention; wherein, Figure 2 (a) is a schematic diagram of the structure after the first deep drawing. Figure 2 (b) is a schematic diagram of the structure after the second deep drawing. Figure 2 (c) is the structural diagram after the third deep drawing. Figure 2 (d) is a schematic diagram of the structure after the fourth deep drawing;

[0023] Figure 3 This is a structural diagram of the motor housing made in step 30 in an embodiment of the present invention, wherein: Figure 3 (a) is a schematic diagram of the structure after the first extrusion. Figure 3 (b) is a schematic diagram of the structure after the second extrusion. Figure 3 (c) is a schematic diagram of the structure after the third extrusion. Figure 3 (d) is a schematic diagram of the structure after the fourth extrusion; Figure 3 (e) is a schematic diagram of the structure after the fifth extrusion. Figure 3 (f) is the schematic diagram of the structure after the sixth extrusion. Figure 3 (g) is a schematic diagram of the structure after the seventh extrusion. Figure 3 (h) is a schematic diagram of the structure after the eighth extrusion;

[0024] Figure 4 1 is a structural diagram of a motor housing made according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0026] The motor housing of the embodiment of the present invention is made of aluminum alloy, and the height of the motor housing finally manufactured is H. Figure 4As shown, the motor housing of this embodiment is a stepped cylindrical structure, comprising an upper cylinder 1 and a lower cylinder 2 connected to the upper cylinder 1. The upper cylinder 1 and the lower cylinder 2 are coaxial. The height of the upper cylinder 1 is 10-12mm, for example 10mm, 10.8mm, 11.3mm or 12mm, the inner diameter is 7-8mm, for example 7mm, 7.4mm, 7.6mm or 8mm, and the outer diameter is 10.5-12mm, for example 10.5mm, 11mm, 11.4mm or 12mm; the height of the lower cylinder 2 is 50-60mm, for example 50mm, 52.4mm, 57.5mm or 60mm, the inner diameter is 37-43mm, for example 37mm, 38.5mm, 41.4mm or 43mm, and the outer diameter is 43-48mm, for example 43mm, 44.3mm, 45.4mm, 47.2mm or 48mm.

[0027] like Figure 1 As shown, a method for preparing a motor housing by using an extrusion thickening and deep drawing forming process according to an embodiment of the present invention comprises the following steps:

[0028] Step 10, through experimental measurement and simulation analysis methods, the aluminum alloy plate drawing coefficient set for each process is obtained. Both the experimental measurement and simulation analysis methods are prior art. The experimental measurement is an experimental measurement of the drawing coefficient. The simulation analysis method can be implemented using a variety of existing simulation software, such as Dynaform or Pamstamp software. The preset aluminum alloy plate drawing coefficient is obtained by experimental measurement and substituted into the simulation software. According to the simulation results, it is determined whether the preset aluminum alloy plate drawing coefficient needs to be adjusted. If the simulation results show good forming and the parts are not cracked or wrinkled, then the preset aluminum alloy plate drawing coefficient is used as the aluminum alloy plate drawing coefficient for each process. If the simulation results show obviously poor forming and the parts are cracked or wrinkled, then the preset aluminum alloy plate drawing coefficient is adjusted until the forming is good and the parts are not cracked or wrinkled. The adjusted aluminum alloy plate drawing coefficient is used as the aluminum alloy plate drawing coefficient for each process.

[0029] As a preferred example, in step 10, the first drawing coefficient of the aluminum alloy plate is 0.5 to 0.6, and the subsequent drawing coefficient is 0.8 to 0.9. When drawing the aluminum alloy plate and extruding the upper motor housing, the drawing coefficient requirements of the aluminum alloy plate are met to ensure that the aluminum alloy plate will not crack during the drawing and extrusion process, thereby improving the qualified rate of finished products.

[0030] Step 20, according to the drawing coefficient of the aluminum alloy plate, the aluminum alloy plate is drawn to obtain a first motor housing. The height of the first motor housing is H. The first motor housing includes an upper motor housing and a lower motor housing. The upper motor housing is located above the lower motor housing, and the upper motor housing has a convex arc surface.

[0031] Step 20 is to produce the first motor housing through a deep drawing process. The height of the first motor housing is equal to the height of the motor housing finally produced. This ensures that there is sufficient material for subsequent forming. In step 30, the upper motor housing is extruded, and the material flows toward the cylinder wall of the upper motor housing, increasing the thickness of the cylinder wall and reducing cracking. The upper motor housing has a convex curved surface, which is convenient for the subsequent extrusion process operation, and the upper motor housing is transformed from a convex curved surface into a hollow cylinder.

[0032] Preferably, in step 20, the aluminum alloy plate is deep drawn at least 3 times to obtain the first motor housing; the lower motor housing is a hollow cylinder. The upper motor housing is a hollow hemisphere. The lower motor housing and the upper motor housing are connected. The aluminum alloy plate is deep drawn multiple times to obtain the first motor housing. Through multiple deep drawing, the first motor housing is prevented from cracking during the drawing process. Each deep drawing meets the drawing coefficient requirements of the aluminum alloy plate. The upper motor housing is drawn into an arc structure, which makes it more convenient to extrude the upper motor housing and makes it less likely for the upper motor housing to crack during extrusion. Preferably, in step 20, the aluminum alloy plate is deep drawn 4 to 5 times to form the first motor housing. If only one deep drawing is performed to form the first motor housing, the deformation will be too large and the first motor housing will crack. This preferred example performs 4 to 5 deep drawing to ensure that the first motor housing will not crack.

[0033] Step 30, use an extrusion process to reduce the diameter of the upper motor shell until the motor shell is obtained; during the extrusion process, the height of the upper motor shell and the height of the lower motor shell remain unchanged. In this step, during the extrusion of the upper motor shell, the height of the upper motor shell and the height of the lower motor shell remain unchanged. This ensures the accuracy of the drawn part while facilitating the flow of material and shrinking the upper motor shell. The upper motor shell of the first motor shell corresponds to the upper cylinder 1 of the motor shell that is finally obtained. The lower motor shell of the first motor shell corresponds to the lower cylinder 2 of the motor shell that is finally obtained.

[0034] The height of the first motor shell made in step 20 is equal to the height of the final motor shell. In the process of extruding the upper motor shell in step 30, since the height of the upper motor shell remains unchanged, there is surplus material in the upper motor shell part, and the size of the upper motor shell is obtained by successive extrusion, drawing and shrinking. According to the principle of equal volume, after each extrusion in step 30, the diameter of the upper motor shell becomes smaller. While the height remains unchanged, the surplus material of the upper motor shell is accommodated by increasing the wall thickness of the upper motor shell, thereby reducing the tendency of the upper motor shell to crack. In the prior art, during the deep drawing process of the motor shell, the upper motor shell is prone to cracking due to its small size and thin wall. In the present application, the wall thickness of the upper motor shell is increased after each extrusion process to reduce the risk of cracking.

[0035] As a preferred example, in step 30, the thickness that needs to be increased when the upper motor shell wall is extruded is obtained according to formula (1):

[0036] △T=△V÷S Formula (1)

[0037] Among them, △T represents the increased thickness of the upper motor shell wall, unit: mm; △V represents the volume difference between the lower motor shell wall and the upper motor shell wall of the same height, unit: mm 3 ; S represents the surface area of ​​the upper motor housing, unit: mm 2 . The increased thickness of the cylinder wall during each extrusion of the upper motor housing is calculated according to formula (1). According to the increased thickness of the cylinder wall, the gap between the concave and convex dies in the mold is adjusted during each extrusion. When the upper motor housing is extruded, the drawing coefficient of the aluminum alloy needs to be met. That is, during the first extrusion, the drawing coefficient of the aluminum alloy plate is 0.5-0.6; in the subsequent extrusion process, the drawing coefficient is 0.8-0.9.

[0038] In the above method, the drawing coefficient of the aluminum alloy plate is first calculated, and the aluminum alloy plate is subjected to multi-step drawing according to the drawing coefficient to obtain the first motor housing; the upper motor housing on the upper part of the first motor housing is formed by extrusion, and when the upper motor housing is extruded, the diameter is gradually reduced by extrusion. In this process, the height of the first motor housing does not change. By adopting the forming method of increasing the wall thickness by multiple extrusions, cracking of the upper motor housing during the forming process is avoided, and the forming efficiency and qualified rate of the motor housing are improved.

[0039] As a preferred example, in step 30, an extrusion process is performed using a forming mold; the forming mold is provided with a concave and convex mold, and the gap between the concave and convex molds is the thickness of the barrel wall of the upper motor shell during each extrusion process. Specifically, except for the first extrusion, each time the extrusion is performed, the increased thickness of the barrel wall of the upper motor shell in this extrusion process is first calculated, and the increased thickness is added to the thickness of the barrel wall of the upper motor shell after the last extrusion to obtain the thickness of the barrel wall of the upper motor shell in this extrusion process. The gap between the concave and convex molds is adjusted so that the gap between the concave and convex molds is equal to the thickness of the barrel wall of the upper motor shell in this extrusion. As long as the gap between the concave and convex molds is kept consistent with the thickness of the barrel wall of the upper motor shell in each extrusion process, the mold of the upper motor shell in each extrusion process can be obtained, thereby realizing rapid mass production.

[0040] In this embodiment, a die is provided for each deep drawing and extrusion, and the aluminum alloy motor casing is formed by deep drawing and extrusion through the die. By using this method to deep draw the aluminum alloy motor casing, the cost of a single casing can be reduced by 20% compared to the die-casting method for processing the motor casing. The production of a single casing of a die-cast casing takes 2 to 3 minutes. Through the extrusion thickening and deep drawing processing method of the present invention, 10 to 18 casings can be produced per minute, and the production efficiency is greatly improved. This method can realize the deep drawing and extrusion processing of aluminum alloy motor casings at room temperature, promoting the development of the motor casing manufacturing industry. The room temperature is 18 to 25°C.

[0041] As a preferred example, in step 30, the upper motor shell is extruded 7 to 8 times; each extrusion gradually reduces the diameter of the upper motor shell. Each time the upper motor shell is extruded, the drawing coefficient in step 10 is followed. When the upper motor shell is extruded, the height of the first motor shell, the diameter of the lower motor shell, the height of the lower motor shell, and the height of the upper motor shell remain unchanged, the diameter of the upper motor shell is reduced, and the thickness of the barrel wall is increased. The diameter of the upper motor shell is gradually reduced through multiple extrusion processes to ensure that the upper part of the first motor shell will not crack during the forming process of the upper motor shell, thereby improving the qualified rate of the motor shell.

[0042] As a preferred example, each deep drawing and extrusion corresponds to a forming die. Multiple dies are set to perform deep drawing and forming operations on the aluminum alloy motor housing, forming an assembly line operation of die processing and forming, thereby improving the efficiency of motor housing forming. Each die parameter is obtained through calculation and experiment, which improves the forming efficiency while ensuring the qualified rate of the motor housing.

[0043] The following is an example.

[0044] The height of the finished motor housing is 69.2 mm. A method for preparing a motor housing comprises:

[0045] Step 10, take an aluminum alloy plate with a diameter of 134 mm and a thickness of 2 mm. Through experimental measurement and simulation analysis methods, the aluminum alloy plate drawing coefficients for setting each process are obtained. The drawing process is 4 times. The first drawing coefficient is 0.582, and the subsequent three drawing coefficients are 0.808, 0.809, and 0.890 respectively.

[0046] Step 20, according to the drawing coefficient of the aluminum alloy sheet, the aluminum alloy sheet is drawn to obtain a first motor housing; the height of the first motor housing is 69.2 mm; the first motor housing includes an upper motor housing and a lower motor housing. Figure 2 As shown in (a), the diameter of the motor housing is 78 mm and the height is 38.7 mm. After the second drawing, Figure 2 As shown in (b), the diameter of the motor housing is 63 mm and the height is 55.3 mm. After the third drawing, Figure 2 As shown in (c), the diameter of the motor housing is 51 mm and the height is 66.3 mm. After the fourth drawing, Figure 2 As shown in (d), the diameter of the motor housing is 45.4 mm and the height is 69.2 mm.

[0047] Step 30, using an extrusion process to reduce the diameter of the upper motor housing until the motor housing is obtained; during the extrusion process, the height of the upper motor housing and the height of the lower motor housing remain unchanged. In this step, the upper motor housing is extruded 8 times; each extrusion gradually reduces the diameter of the upper motor housing. In the 8 extrusions, the first drawing coefficient is 0.858, and the subsequent 7 drawing coefficients are 0.813, 0.833, 0.840, 0.952, 0.75, 0.867, and 0.877 respectively. Among them, after the first extrusion, if Figure 3 As shown in (a), the outer diameter of the cylinder of the upper motor housing is 38.22mm, the height is 11.2mm, and the wall thickness is 1.767mm.

[0048] After the second extrusion, Figure 3 As shown in (b), the outer diameter of the cylinder of the upper motor housing is 31.6 mm, the height is 11.2 mm, and the wall thickness is 2.044 mm.

[0049] After the third extrusion, Figure 3 As shown in (c), the outer diameter of the cylinder of the upper motor housing is 26.3mm, the height is 11.2mm, and the wall thickness is 2.241mm.

[0050] After the fourth squeeze, Figure 3 As shown in (d), the outer diameter of the cylinder of the upper motor housing is 22.5mm, the height is 11.2mm, and the wall thickness is 2.412mm.

[0051] After the fifth squeeze, Figure 3 As shown in (e), the outer diameter of the cylinder of the upper motor housing is 21.6 mm, the height is 11.2 mm, and the wall thickness is 2.52 mm.

[0052] After the sixth squeeze, Figure 3 As shown in (f), the outer diameter of the cylinder of the upper motor housing is 17.7 mm, the height is 11.2 mm, and the wall thickness is 2.758 mm.

[0053] After the seventh squeeze, Figure 3 As shown in (g), the outer diameter of the cylinder of the upper motor housing is 15.7 mm, the height is 11.2 mm, and the wall thickness is 2.872 mm.

[0054] After the eighth squeeze, Figure 3 As shown in (h), the outer diameter of the cylinder of the upper motor housing is 14.2mm, the height is 11.2mm, and the wall thickness is 2.932mm.

[0055] In the above 8 extrusions, the lower motor housing maintains the shape and size after the fourth deep drawing.

[0056] The motor housing prepared by the above method has no cracks, especially the upper cylinder 1 has no cracks.

[0057] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above specific embodiments. The above specific embodiments and the description in the specification are only for further illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of the present invention to be protected is defined by the claims and their equivalents.

Claims

1. A method for preparing a motor housing by using an extrusion thickening and deep drawing process, characterized in that: The motor shell is made of aluminum alloy, and the finally manufactured motor shell is a stepped cylindrical structure, comprising an upper cylinder (1) and a lower cylinder (2) connected to the upper cylinder (1), and the upper cylinder (1) and the lower cylinder (2) are coaxial; the height of the finally manufactured motor shell is H; the method comprises the following steps: Step 10, obtaining the aluminum alloy sheet drawing coefficient for each process through experimental measurement and simulation analysis method; Step 20, drawing the aluminum alloy plate according to the drawing coefficient of the aluminum alloy plate to obtain a first motor housing; the height of the first motor housing is H; the first motor housing includes an upper motor housing and a lower motor housing; the upper motor housing is located above the lower motor housing, and the upper motor housing has a convex arc surface; Step 30, using an extrusion process to reduce the diameter of the upper motor housing until the motor housing is obtained; during the extrusion process, the height of the upper motor housing and the height of the lower motor housing remain unchanged.

2. The method according to claim 1, characterized in that In step 10, the first drawing coefficient of the aluminum alloy plate is 0.5-0.6, and the subsequent drawing coefficient is 0.8-0.

9.

3. The method according to claim 1, characterized in that In the step 20, the aluminum alloy plate is deep drawn at least three times to obtain a first motor housing; the lower motor housing is a hollow cylinder; the upper motor housing is a hollow hemisphere; the lower motor housing and the upper motor housing are connected.

4. The method according to claim 3, characterized in that In the step 20, the aluminum alloy plate is deep drawn 4 to 5 times to obtain the first motor housing.

5. The method according to claim 1, characterized in that In the step 30, an extrusion process is performed using a forming die; the forming die is provided with a concave and convex die, and the gap between the concave and convex dies is the thickness of the cylinder wall of the upper motor shell during each extrusion process.

6. The method according to claim 1, characterized in that In step 30, the upper motor housing is squeezed 7 to 8 times; each squeezing stepwise reduces the diameter of the upper motor housing.

7. The method according to claim 1, characterized in that In the motor housing obtained in step 30, the upper cylinder (1) has a height of 10 to 12 mm, an inner diameter of 7 to 8 mm, and an outer diameter of 10.5 to 12 mm.

8. The method according to claim 7, characterized in that In the motor housing obtained in step 30, the lower cylinder (2) has a height of 50 to 60 mm, an inner diameter of 37 to 43 mm, and an outer diameter of 43 to 48 mm.

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