Cold forging method for manufacturing crankshaft blanks for air conditioners

Abstract

The present invention relates to a method for manufacturing crankshaft blanks, specifically a cold forging method for manufacturing crankshaft blanks for air conditioners. [Solution] This method involves cold forging multiple cylindrical steel blanks for cold forging to manufacture crankshaft blanks for air conditioners, resulting in low material usage and low costs. Furthermore, since heating is not required in cold forging, the material properties of the cylindrical steel blanks for cold forging do not change, guaranteeing the performance of the material. This eliminates the need for additional processing of the material in subsequent processes, thus avoiding complexity in subsequent steps.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a crankshaft, and particularly to a cold forging method for manufacturing a crankshaft blank for an air conditioner.

Background Art

[0002] The crankshaft is an important component of a rotary air conditioner compressor, and its performance requirements are high. The conventional method is to produce a crankshaft blank by die casting and then form it by machining, or to produce it by machining a bar.

[0003] In production by the casting method, the processes from mold manufacturing to product production are very complicated. In addition, defects such as pores and slag inclusion in the product are inevitable, and the defective rate is high. In addition, it is necessary to ensure a relatively large wall thickness for the casting blank, and then it goes through a plurality of processing steps, so the material utilization rate is low, the processing process is complicated, and the production efficiency is low. Furthermore, the casting process consumes a large amount of energy and generates a lot of dust, which is likely to cause environmental pollution.

[0004] When producing a bar by machining, on the one hand, the cutting cost is high and the material performance cannot be fully utilized. On the other hand, machining of slender holes is also a problem. Furthermore, the cost is relatively high compared with the casting method.

[0005] Therefore, a method with a short process, low energy consumption, environmental friendliness, and full utilization of the material characteristics of section steel has become an urgent problem to be solved by researchers in this field in order to realize the manufacture of a crankshaft for an air conditioner.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The technical problem to be solved by the present invention is to establish a method for manufacturing a crankshaft blank for an air conditioner, which has a short process, low energy consumption, environmental friendliness, and can fully utilize the material characteristics of section steel. [Means for solving the problem]

[0007] To solve the above technical problems, the technical means employed by the present invention are as follows.

[0008] The present invention is a cold forging method for manufacturing a crankshaft blank for an air conditioner, and includes the following steps.

[0009] Process S1: Select a steel material suitable for cold forging and cut a cylindrical steel blank for cold forging to the appropriate length based on the specifications of the air conditioner compressor crankshaft.

[0010] Process S2: A positioning hole is cold-forged into one end face of a cylindrical steel blank for cold forging to form the first cold-forged blank.

[0011] Step S3: Cold forging is performed on the first cold forged blank along the axis direction of the positioning hole to form a second cold forged blank having a first axial hole.

[0012] Step S4: The inner and outer diameters of the first shaft hole of the second cold-forged blank are reduced by cold forging to form a third cold-forged blank that is continuous in the axial direction with the main shaft portion and the large diameter portion. The main shaft portion has a second shaft hole formed by the reduction in diameter of the first shaft hole.

[0013] Step S5: A portion of the large-diameter section at the other end of the third cold-forged blank is reduced in diameter by cold forging to form a fourth cold-forged blank in which the main shaft section, intermediate section, and first sub-shaft section are sequentially arranged in the axial direction.

[0014] Step S6: The fourth cold-forged blank is cold-forged again to form the cold-forged crankshaft blank having a main shaft portion, an eccentric portion, and a second sub-shaft portion.

[0015] Furthermore, process S6 includes the following processes S61 to S63.

[0016] Step S61: The first sub-shaft portion of the fourth cold-forged blank is subjected to a diameter reduction by secondary cold forging to form a fifth cold-forged blank having a main shaft portion, an intermediate portion, and a second sub-shaft portion.

[0017] Step S62: The intermediate portion and / or first sub-shaft portion of the fourth cold-forged blank or the fifth cold-forged blank is cold-forged to form a sixth cold-forged blank having a main shaft portion, a burr eccentric portion and a second sub-shaft portion.

[0018] Step S63: Remove burrs from the eccentric portion of the cold-forged blank body and form the eccentric portion.

[0019] Furthermore, in step S2, the outer diameter of the first cold-forged blank coincides with the outer diameter of the cylindrical steel blank for cold forging, and the axis of the positioning hole is coaxial with the axis of the first cold-forged blank.

[0020] Furthermore, in process S3, the axial length of the first shaft hole is greater than the axial length of the positioning hole, the inner diameter of the first shaft hole is the same as the inner diameter of the positioning hole, and the length of the second cold-forged blank is longer than the length of the first cold-forged blank.

[0021] Furthermore, in step S4, the inner diameter of the second shaft hole is smaller than the inner diameter of the first shaft hole, and the axial length of the second shaft hole is longer than the axial length of the first shaft hole.

[0022] The third cold-forged blank has a main shaft portion in the front, a large-diameter portion in the rear, and a first transition portion connecting the main shaft portion and the large-diameter portion. The outer diameter of the large-diameter portion is the same as the outer diameter of the second cold-forged blank, and the outer diameter of the main shaft portion is smaller than the outer diameter of the large-diameter portion.

[0023] Furthermore, in step S5, the first sub-shaft portion and the main shaft portion are located on both sides of the intermediate portion, and a second transition portion is provided between the first sub-shaft portion and the intermediate portion.

[0024] The outer diameter of the middle part is made to coincide with the outer diameter of the large-diameter part. The outer diameter of the first auxiliary shaft part is smaller than the outer diameter of the middle part. The total axial length of the first auxiliary shaft part, the middle part, and the second transition part is longer than the axial length of the large-diameter part.

[0025] Furthermore, in step S6, the outer diameter of the second auxiliary shaft part is smaller than the outer diameter of the first auxiliary shaft part, the outer diameter of the eccentric part is larger than the outer diameter of the middle part, and the axial length of the eccentric part is shorter than the total axial length of the middle part, the first transition part, and the second transition part.

[0026] Furthermore, in step S61, the middle part of the fifth cold forging blank body coincides with the middle part of the fourth cold forging blank body in terms of axial length and outer diameter, and the axial length of the second auxiliary shaft part installed at the rear end part of the fifth cold forging blank body is longer than the axial length of the first auxiliary shaft part. The outer diameter of the second auxiliary shaft part is smaller than the outer diameter of the first auxiliary shaft part, the axial length of the third transition part installed between the middle part of the fifth cold forging blank body and the middle part of the main shaft part is smaller than the axial length of the first transition part, and the axial length of the fourth transition part installed between the middle part of the fifth cold forging blank body and the second auxiliary shaft part is longer than the axial length of the second transition part.

[0027] Furthermore, in step S62, the outer diameter of the burr eccentric part is larger than the outer diameter of the middle part, and the axial length of the burr eccentric part is shorter than the total axial length of the middle part, the third transition part, and the fourth transition part.

[0028] In step S63, the outer diameters of the eccentric part and the burr eccentric part are the same.

[0029] Furthermore, in step S1, the steel materials suitable for cold forging are 40Cr, 20Cr, and 45 steel.

Advantages of the Invention

[0030] This invention relates to a method for manufacturing a crankshaft blank for air conditioners using a cold forging method. This method involves cold forging a cylindrical steel blank for cold forging multiple times to produce a crankshaft blank for air conditioners. This method uses less material and is cost-effective. Furthermore, since cold forging does not require heating, the material properties of the cylindrical steel blank for cold forging are not altered, and the performance of the material is maintained. As a result, there is no need to perform additional processing on the material in subsequent processes, thus avoiding complexity in subsequent steps.

[0031] The present invention will be further described based on the drawings and embodiments. [Brief explanation of the drawing]

[0032] [Figure 1] This is a schematic diagram of the structure of a cylindrical steel blank for cold forging. [Figure 2] This is a schematic diagram of the structure of the first cold-forged blank. [Figure 3] This is a schematic diagram of the structure of the second cold-forged blank. [Figure 4] This is a schematic diagram of the structure of the third cold-forged blank. [Figure 5] This is a schematic diagram of the structure of the fourth cold-forged blank. [Figure 6] This is a schematic diagram of the structure of the fifth cold-forged blank. [Figure 7] This is a schematic diagram of the structure of a sixth cold-forged blank body having a burred eccentric section. [Figure 8] This is a schematic three-dimensional view of a sixth cold-forged blank body having a burred eccentric section. [Figure 9] This is a schematic diagram of the structure of a cold-forged crankshaft blank. [Figure 10] This is a schematic diagram of a cold-forged crankshaft blank. [Modes for carrying out the invention]

[0033] The present invention will be described in detail below with reference to the drawings. These drawings are all simplified schematic diagrams and only show the basic structure of the present invention; therefore, only the components relevant to the present invention are shown.

[0034] First, in Figure 3, the left portion of the second cold-forged blank body 2 is designated as the front section, the right portion as the rear section, and the portion between the front and rear sections as the intermediate section. [Examples]

[0035] The present invention is a cold forging method for manufacturing a crankshaft blank for an air conditioner, and includes the following steps.

[0036] As shown in Figure 1, in step S1, a structural steel, wire, or bar suitable for cold forging is selected. 40Cr, 20Cr, and 45 steel are used as materials; in this embodiment, 40Cr is used. A cylindrical steel blank 01 for cold forging is cut to an appropriate length based on the specifications of the air conditioner compressor crankshaft.

[0037] As shown in Figure 2, in step S2, a positioning hole 11 is cold-forged into the end face of the cylindrical steel blank 01 for cold forging, i.e., the left end face in Figure 2, to form the first cold-forged blank body 1. The outer diameter of the first cold-forged blank body 1 is the same as the outer diameter of the cylindrical steel blank 01 for cold forging, and the axis of the positioning hole 11 is coaxial with the axis of the first cold-forged blank body 1. The purpose of cold-forging the positioning hole 11 is to accurately position it during the subsequent cold forging of the first shaft hole 21.

[0038] As shown in Figure 3, in step S3, cold forging is performed along the axial direction of the positioning hole 11 of the first cold forged blank body 1 to form a second cold forged blank body 2 having a first axial hole 21. The axial length of the first axial hole 21 is greater than the axial length of the positioning hole 11, and the inner diameter of the first axial hole 21 is the same as the inner diameter of the positioning hole 11. The length of the second cold forged blank body 2 is longer than the length of the first cold forged blank body 1.

[0039] Based on process S2, the first shaft hole 21 is cold forged along the positioning hole 11. The axial length of the first shaft hole 21 is longer than the axial length of the positioning hole 11 in S2. At the same time, the second cold forged blank 2 is stretched, and the length of the second cold forged blank 2 becomes greater than the length of the first cold forged blank 1.

[0040] As shown in Figure 4, in step S4, the inner and outer diameters of the front end of the second cold-forged blank body 2 shown in Figure 3 are reduced by cold forging to form a third cold-forged blank body 3 having a second shaft hole 31. Since the second shaft hole 31 is formed by reducing the diameter of the first shaft hole 21, the inner diameter of the second shaft hole 31 is smaller than the inner diameter of the first shaft hole 21, and the axial length of the second shaft hole 31 is longer than the axial length of the first shaft hole 21. The third cold-forged blank body 3 has a main shaft portion 32 at the front end, a large-diameter portion 33 at the rear end, and a first transition portion 34 connecting the main shaft portion 32 and the large-diameter portion 33. The outer diameter of the large-diameter portion 33 is the same as the outer diameter of the second cold-forged blank body 2, and the outer diameter of the main shaft portion 32 is smaller than the outer diameter of the large-diameter portion 33.

[0041] Based on process S3, the inner and outer diameters of the front end of the second cold-forged blank 2 are reduced in diameter by cold forging. The rear end of the second cold-forged blank 2 remains unchanged; that is, the outer diameter of the large-diameter portion 33 is made to match the outer diameter of the second cold-forged blank 2. The second shaft hole 31 at the front end of the third cold-forged blank 3 is reduced in size compared to the inner diameter of the first shaft hole 21 in S3, and its axial length increases. The main shaft portion 32 also has a reduced inner diameter compared to the inner diameter of the front end of the second cold-forged blank 2 in process S3, and its axial length increases. The main shaft portion 32 thus formed becomes the main shaft portion 32 of the final product, the cold-forged crankshaft blank 7.

[0042] As shown in Figure 5, in step S5, the large-diameter portion 33 (i.e., the rightmost portion in Figure 5) of the third cold-forged blank body 3 is reduced in diameter by cold forging to form a fourth cold-forged blank body 4 having a main shaft portion 32, an intermediate portion 42, and a first sub-shaft portion 41. The intermediate portion 42 is located to the left of the first sub-shaft portion 41, and a second transition portion 43 is provided between the first sub-shaft portion 41 and the intermediate portion 42. The first sub-shaft portion 41 and the main shaft portion 32 are located on either side of the intermediate portion 42. The outer diameter of the intermediate portion 42 is made to match the outer diameter of the large-diameter portion 33 of the third cold-forged blank body 3. The outer diameter of the first sub-shaft portion 41 is smaller than the outer diameter of the intermediate portion 42, and the total axial length of the first sub-shaft portion 41, the intermediate portion 42, and the second transition portion 43 is longer than the axial length of the large-diameter portion 33.

[0043] In process S5, the large-diameter portion 33 of the third cold-forged blank 3 is cold-forged. The large-diameter portion 33 forms a first sub-shaft portion 41 and an intermediate portion 42 by cold forging. The outer diameter of the first sub-shaft portion 41 is smaller than the outer diameter of the intermediate portion 42, and the outer diameter of the intermediate portion 42 is made to match the outer diameter of the large-diameter portion 33 in process S4. At the same time, a second transition portion 43 for connecting the intermediate portion 42 and the first sub-shaft portion 41 is formed by cold forging.

[0044] As shown in Figures 9-10, in step S6, cold forging is continued on the fourth cold forged blank 4 to form a cold forged crankshaft blank 7 having a main shaft portion 32, an eccentric portion 71, and a second sub-shaft portion 51.

[0045] In step S6, the second sub-shaft portion 51 is formed by reducing the diameter of the first sub-shaft portion 41. Therefore, the axial length of the second sub-shaft portion 51 is greater than the axial length of the first sub-shaft portion 41, and the outer diameter of the second sub-shaft portion 51 is smaller than the outer diameter of the first sub-shaft portion 41. The eccentric portion 71 is formed by upsetting the first transition portion 34, the intermediate portion 42, and the second transition portion 43. The axial length of the eccentric portion 71 is shorter than the axial length of the intermediate portion 42, and the outer diameter of the eccentric portion 71 is longer than the outer diameter of the intermediate portion 42. [Examples]

[0046] This embodiment is generally the same as the process in Embodiment 1, but differs in the following points.

[0047] (1) In process S1, 20Cr is selected as the steel material suitable for cold forging.

[0048] (ii) In step S6, step S61 is further provided.

[0049] As shown in Figure 6, in step S61, the diameter of the downstream portion (i.e., the first sub-shaft portion 41) of the fourth cold-forged blank body 4 is reduced by secondary cold forging to form the fifth cold-forged blank body 5. The intermediate portion 42 of the fifth cold-forged blank body 5 is made to match the axial length and outer diameter of the intermediate portion 42 of the fourth cold-forged blank body 4. The axial length of the second sub-shaft portion 51 located at the rear end of the fifth cold-forged blank body 5 is greater than the axial length of the first sub-shaft portion 41. The outer diameter of the second sub-shaft portion 51 is smaller than the outer diameter of the first sub-shaft portion 41. Also, the axial length of the third transition portion 52, located between the intermediate portion 42 and the main shaft portion 32 of the fifth cold-forged blank body 5, is smaller than the axial length of the first transition portion 34 of the fourth cold-forged blank body 4. The axial length of the fourth transition section 53, which is provided between the intermediate section 42 and the second sub-shaft section 51 of the fifth cold-forged blank body 5, is longer than the axial length of the second transition section 43.

[0050] In process S61, the first sub-shaft portion 41 is further stretched by cold forging to form the second sub-shaft portion 51. At the same time, the second transition portion 43 is stretched by cold forging to become the fourth transition portion 53, and the first transition portion 34 is compressed by cold forging to become the third transition portion 52. The second sub-shaft portion 51 that has undergone cold forging in process S6 becomes the second sub-shaft portion 51 of the final cold-forged crankshaft blank 7. [Examples]

[0051] This embodiment is generally the same as the process in Embodiment 1, but differs in the following points.

[0052] (1) In process S1, the steel material suitable for cold forging is 45 steel.

[0053] (ii) Step S6 further comprises steps S62 and S63.

[0054] As shown in Figures 7-8, in step S62, the intermediate portion 42, the first transition portion 34, and the second transition portion 43 of the fourth cold forged blank body 4 are cold forged to form the sixth cold forged blank body 6. A burr eccentric portion 61 exists between the second sub-shaft portion 51 and the main shaft portion 32 of the sixth cold forged blank body 6.

[0055] In step S62, the first transition section 34, the intermediate section 42, and the second transition section 43 are cold forged to form a sixth cold forged blank body 6 having a burr eccentric section 61. The shapes of the main shaft section 32 and the second shaft hole 31 of the sixth cold forged blank body 6 are made to match those of the third cold forged blank body 3 and the fourth cold forged blank body 4. The outer diameter of the second sub-shaft section 51 of the sixth cold forged blank body 6 is smaller than the outer diameter of the first sub-shaft section 41. Both sides of the burr eccentric section 61 are formed into flat surfaces by cold forging.

[0056] Step S63: Remove the burrs 62 from the eccentric portion 61 on the cold forged blank body 6 to form the eccentric portion 71. [Examples]

[0057] This embodiment is generally the same as the process in Embodiment 2, but differs in the following points.

[0058] (1) In process S1, the steel material suitable for cold forging is 40Cr.

[0059] (ii) After step S61, steps S62 and S63 are further provided.

[0060] As shown in Figures 7-8, in step S62, the intermediate portion 42, third transition portion 52, and fourth transition portion 53 of the fifth cold forged blank body 5 are cold forged to form the sixth cold forged blank body 6. A burr eccentric portion 61 exists between the second sub-shaft portion 51 and the main shaft portion 32 of the sixth cold forged blank body 6.

[0061] In step S62, the third transition section 52, the fourth transition section 53, and the intermediate section 42 are cold-forged to form a sixth cold-forged blank body 6 having a burr eccentric section 61. The main shaft section 32 and the second shaft hole 31 of the sixth cold-forged blank body 6 are made to match those of the third cold-forged blank body 3. The second sub-shaft section 51 of the sixth cold-forged blank body 6 matches the second sub-shaft section 51 of the fifth cold-forged blank body 5, but differs in that the third transition section 52, the fourth transition section 53, and the intermediate section 42 are compression cold-forged to form the burr eccentric section 61. Both sides of the burr eccentric section 61 are formed flat by cold forging.

[0062] Step S63: The burrs 62 of the eccentric portion 61 are removed to form the eccentric portion 71. The outer diameter of the eccentric portion 71 is larger than the outer diameter of the intermediate portion 42, and the axial length of the eccentric portion 71 is shorter than the sum of the axial lengths of the intermediate portion 42, the third transition portion 52, and the fourth transition portion 53.

[0063] In step S63, the burrs 62 formed on the eccentric portion 61 after cold forging in step S62 are cut and removed to form a cold forged crankshaft blank 7 having an eccentric portion 71.

[0064] The cold-forged crankshaft blanks 7 manufactured in Examples 1, 2, 3, and 4 described above are subjected to subsequent precision machining to form an air conditioner crankshaft.

[0065] The embodiments described above are merely preferred examples of the present invention, and those skilled in the art can make various changes and modifications without departing from the technical spirit of the invention. The technical scope of the present invention is not limited to what is described in the specification, but should be determined based on the claims. [Explanation of symbols]

[0066] 01...Cylindrical steel blank for cold forging 1. First cold-forged blank 11...Positioning holes 2. Second cold forged blank 21...First shaft hole 3. Third cold-forged blank 31...Second shaft hole 32...Spindle part 33..Large diameter section 34...first transition part 4. Fourth cold forged blank 41...First subshaft part 42...Middle section 43...Second transition part 5. Fifth cold-forged blank 51...Second subshaft part 52...Third transition part 53...Fourth transition part 6. Sixth cold forged blank 61...Eccentric part 62...Bali 7. Cold-forged crankshaft blanks 71...Eccentric part

Claims

1. A cold forging method for manufacturing a crankshaft blank for an air conditioner, characterized by comprising the following steps: Process S1: Select a steel material suitable for cold forging and cut a cylindrical steel blank (01) of appropriate length for cold forging based on the specifications of the air conditioner compressor crankshaft. Step S2: A positioning hole (11) is cold-forged into one end face of a cylindrical steel blank (01) for cold forging to form a first cold-forged blank body (1). Step S3: Cold forging is performed axially along the positioning hole (11) of the first cold forged blank (1) to form a second cold forged blank (2) having a first axial hole (21). Step S4: The internal and external diameters of the second cold-forged blank (2) at the position of the first shaft hole (21) are reduced by cold forging to form a third cold-forged blank (3) in which a main shaft portion (32) and a large diameter portion (33) are sequentially arranged in the axial direction. The main shaft portion (32) has a second shaft hole (31) formed by the reduction in diameter of the first shaft hole (21). The formed main shaft portion (32) becomes the main shaft portion (32) of the cold-forged crankshaft blank (7). The external diameter of the large diameter portion (33) matches the external diameter of the second cold-forged blank (2), and the external diameter of the main shaft portion (32) is smaller than the external diameter of the large diameter portion (33). Step S5: A portion of the large-diameter section (33) at the other end of the third cold-forged blank (3) is reduced in diameter by cold forging to form a fourth cold-forged blank (4) in which the main shaft section (32), intermediate section (42), and first sub-shaft section (41) are arranged in the axial direction. A cold forging manufacturing method characterized by comprising the step S6: cold forging the intermediate portion (42) and the first sub-shaft portion (41) of the fourth cold forged blank body (4) again to form the cold forged crankshaft blank (7) having a main shaft portion (32), an eccentric portion (71), and a second sub-shaft portion (51).

2. A cold forging method for manufacturing an air conditioner crankshaft blank as described in claim 1, characterized in that step S6 further comprises the following steps, Step S61: The diameter of the first sub-shaft portion (41) of the fourth cold-forged blank (4) is reduced by secondary cold forging to form a fifth cold-forged blank (5) having a main shaft portion (32), an intermediate portion (42), and a second sub-shaft portion (51).

3. A cold forging method for manufacturing an air conditioner crankshaft blank as described in claim 1, characterized in that step S6 further comprises the following steps, Step S62: The intermediate portion (42) and the first sub-shaft portion (41) of the fourth cold-forged blank body (4) are cold-forged to form a sixth cold-forged blank body (6) having a main shaft portion (32), a burr eccentric portion (61), and a second sub-shaft portion (51). Step S63: Remove the burrs (62) on the eccentric portion (61) of the cold-forged blank body (6) and form the eccentric portion (71).

4. A cold forging method for manufacturing an air conditioner crankshaft blank according to claim 2, characterized in that step S6 further comprises the following steps, Step S62: The intermediate portion (42) of the fifth cold-forged blank (5) is cold-forged to form a sixth cold-forged blank (6) having a main shaft portion (32), a burr eccentric portion (61), and a second sub-shaft portion (51). Step S63: Remove the burrs (62) on the eccentric portion (61) of the cold-forged blank body (6) and form the eccentric portion (71).

5. A cold forging method for manufacturing an air conditioner crankshaft blank according to any one of claims 1 to 4, A cold forging manufacturing method characterized in that, in step S2, the outer diameter of the first cold forging blank (1) is the same as the outer diameter of the cylindrical steel blank (01) for cold forging, and the axis of the positioning hole (11) is coaxial with the axis of the first cold forging blank (1).

6. A cold forging method for manufacturing an air conditioner crankshaft blank according to any one of claims 1 to 4, A cold forging manufacturing method characterized by comprising a step S3 in which the axial length of the first shaft hole (21) is greater than the axial length of the positioning hole (11), the inner diameter of the first shaft hole (21) is the same as the inner diameter of the positioning hole (11), and the length of the second cold forged blank body (2) is longer than the length of the first cold forged blank body (1).

7. A cold forging method for manufacturing an air conditioner crankshaft blank according to any one of claims 1 to 4, In step S4, the inner diameter of the second shaft hole (31) is smaller than the inner diameter of the first shaft hole (21), and the axial length of the second shaft hole (31) is longer than the axial length of the first shaft hole (21). A cold forging manufacturing method characterized in that the third cold forged blank (3) has a front main shaft portion (32), a rear large diameter portion (33), and a first transition portion (34) connecting the main shaft portion (32) and the large diameter portion (33).

8. A cold forging method for manufacturing an air conditioner crankshaft blank according to any one of claims 1 to 4, In step S5, the first sub-shaft portion (41) and the main shaft portion (32) are located on both sides of the intermediate portion (42), and a second transition portion (43) is provided between the first sub-shaft portion (41) and the intermediate portion (42). A cold forging manufacturing method characterized in that the outer diameter of the intermediate section (42) is made to match the outer diameter of the large diameter section (33). The outer diameter of the first sub-shaft section (41) is smaller than the outer diameter of the intermediate section (42), and the sum of the axial lengths of the first sub-shaft section (41), the intermediate section (42), and the second transition section (43) is greater than the axial length of the large diameter section (33).

9. A cold forging method for manufacturing an air conditioner crankshaft blank according to any one of claims 1 to 4, A cold forging manufacturing method characterized in that, in step S6, the outer diameter of the second sub-shaft portion (51) is smaller than the outer diameter of the first sub-shaft portion (41), the outer diameter of the eccentric portion (71) is larger than the outer diameter of the intermediate portion (42), and the axial length of the eccentric portion (71) is shorter than the sum of the axial lengths of the intermediate portion (42), the first transition portion (34), and the second transition portion (43).

10. A cold forging method for manufacturing an air conditioner crankshaft blank according to claim 2, A cold forging manufacturing method characterized in that, in step S61, the intermediate portion (42) of the fifth cold forged blank (5) has the same axial length and outer diameter as the intermediate portion (42) of the fourth cold forged blank (4), the axial length of the second sub-shaft portion (51) provided at the rear end of the fifth cold forged blank (5) is greater than the axial length of the first sub-shaft portion (41), and the outer diameter of the second sub-shaft portion (51) is smaller than the outer diameter of the first sub-shaft portion (41), the axial length of the third transition portion (52) located between the intermediate portion (42) and the main shaft portion (32) of the fifth cold forged blank (5) is smaller than the axial length of the first transition portion (34), and the axial length of the fourth transition portion (53) provided between the intermediate portion (42) and the second sub-shaft portion (51) of the fifth cold forged blank (5) is longer than the axial length of the second transition portion (43).

11. A cold forging method for manufacturing an air conditioner crankshaft blank according to any one of claims 3 to 4, In process S62, the outer diameter of the eccentric burr portion (61) is larger than the outer diameter of the intermediate portion (42), and the axial length of the eccentric burr portion (61) is shorter than the sum of the axial lengths of the intermediate portion (42), the third transition portion (52), and the fourth transition portion (53). A cold forging manufacturing method characterized by comprising a step in process S63 in which the outer diameter of the eccentric portion (71) is made to match the outer diameter of the burr eccentric portion (61).

12. A cold forging method for manufacturing an air conditioner crankshaft blank according to any one of claims 1 to 4, characterized in that in step S1, the steel material of the cold forging cylindrical blank (01) is 40Cr, 20Cr, or 45 steel.

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