A powder metallurgy vvt stator sizing die
By designing a positioning mandrel and through hole to fit the forming mold, the tilting problem during VVT stator forming was solved, achieving high-precision perpendicularity and roundness, and improving machining efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI AUTOMOTIVE POWDER METALLURGY CO LTD
- Filing Date
- 2025-08-14
- Publication Date
- 2026-08-04
AI Technical Summary
When manually positioning existing powder metallurgy VVT stator forming dies, the product tends to tilt into the mold cavity, resulting in the inner cavity's perpendicularity and roundness not meeting the requirements, which affects machining accuracy and efficiency.
Design a forming mold that uses four positioning mandrels of equal length to cooperate with the upper forming mold. The positioning mandrels first contact the through hole of the product to ensure that the product enters the mold cavity vertically. Combined with the design of the inner and outer lower forming molds, uniform extrusion is achieved to ensure the verticality of the product and the roundness of the inner cavity.
It improves the perpendicularity and roundness of the VVT stator, provides a good machining reference, and increases machining efficiency by 30%.
Smart Images
Figure CN224586991U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of powder metallurgy technology, specifically to a shaping mold for a powder metallurgy VVT stator. Background Technology
[0002] Powder metallurgy, as a high-tech industry, perfectly combines materials science and metal forming technology, and is widely used in the automotive parts field to leverage its high efficiency, material saving, and energy saving characteristics. The VVT (Variable Valve Timing) in an automotive engine is crucial to the engine's efficiency and performance, thus requiring extremely high precision and performance from the parts within the VVT. In particular, the internal dimensions of the VVT stator require roundness of 0.01mm-0.02mm, perpendicularity of 0.02mm, and surface uniformity. To correct deformation after sintering, a shaping process is used, which involves re-pressurizing the parts in a mold to achieve the required dimensions and precision. After shaping, these VVT stators require further machining to improve precision, and the precision of the shaped blank also affects the precision and efficiency of the machining process.
[0003] In general powder metallurgy product shaping, the product is manually placed in the guide section of the mold. This involves a full-circumference guide section at the die inlet and mandrel entrance. The die is enlarged by 0.2mm-0.3mm on each side according to the part's shape, while the mandrel is reduced by 0.2mm-0.3mm. The joint is smoothly connected with a rounded arc. During shaping, the product is manually placed in the guide section of the mold, and the part remains stably at the inlet. The press is then started, and the upper shaping die vertically presses the part into the mold cavity. The part is then subjected to compression within the mold cavity, resulting in plastic deformation to correct its dimensions and accuracy. (See attached image) Figure 1 As shown, when the VVT stator (product 1) has a large diameter, high precision requirements, and an irregular cross-shaped structure for the inner cavity 102, the roundness requirement of the four arc segments forming the inner cavity 102 is 0.01mm-0.02mm. Each of the four protrusions of the inner cavity 102 is provided with four first through holes 101, the diameter of the first through hole 1 is φ6.5mm, the perpendicularity requirement of the inner cavity 102 to the end face 103 is 0.02mm, and the sintered blank is irregularly deformed, the following technical defects exist: When manually placed, the end face 103 cannot achieve a perpendicular state to the mold in the mold guide section, resulting in positioning offset and tilting. This causes product 1 to be unable to enter the forming section mold cavity vertically when entering from the guide section, the perpendicularity of product 1 cannot meet the requirements, and it enters the mold cavity tilted. The shaping amount varies in different areas of the inner cavity, the roundness of the inner hole is poor, and some areas have scratches and roughening. The inner cavity serves as a reference, which seriously affects the machining clamping and positioning.
[0004] Therefore, how to design a forming mold for a powder metallurgy VVT stator has become an urgent problem to be solved. Utility Model Content
[0005] In view of the problems existing in the prior art, this utility model provides a shaping mold for powder metallurgy VVT stator to solve at least one of the above-mentioned technical problems.
[0006] The technical solution of this utility model is: a shaping mold for a powder metallurgy VVT stator, comprising a product horizontally placed on the upper end of a shaping mandrel. The product has a ring structure, the outer ring of the ring structure is a chain tooth, and the inner ring of the ring structure is provided with four bosses evenly distributed around the circumference. Each boss has a first through hole on its top surface. The inner arc surfaces of the four bosses are on the same circle, and the inner arc surfaces of the four bosses form the inner hole of the product. The lower part of the shaping mandrel is provided with a shaping inner lower mold, a shaping outer lower mold, and a shaping female mold in sequence from the inside to the outside. The top surface of the shaping inner lower mold is provided with four second through holes evenly distributed around the circumference, and the second through holes are arranged one-to-one with the first through holes. A shaping upper mold is provided above the product. The top surface of the shaping upper mold is provided with four stepped holes evenly distributed around the circumference. A positioning mandrel is provided in the stepped hole, and the small end of the positioning mandrel is located in the corresponding first through hole.
[0007] This invention employs four positioning mandrels of equal length. The small end of each positioning mandrel has the same size as the first through hole. The positioning mandrels are fixed by the upper forming mold via a bottom flange. The lower forming mold has four second through holes for engagement with the positioning mandrels during mold closing. During forming, the product is manually placed into the mold cavity guide section. Because the positioning mandrels protrude from the bottom surface of the upper forming mold, as the upper forming mold descends, before the bottom surface of the upper forming mold contacts the top surface of the product, the four positioning mandrels first contact and simultaneously enter the first through hole of the product. Therefore, under the radial action of the four positioning mandrels, the top surface of the product will contact the forming mandrels. Maintaining a vertical entry into the forming section of the mold cavity ensures uniform extrusion and plastic deformation of the product, guaranteeing its perpendicularity, hole diameter, and uniform shaping amount throughout the cavity. This solves the shaping and positioning problem for VVT stator products and avoids tilting issues when the product enters the forming section from the guide section. The product's perpendicularity can be achieved within 0.02 mm, and the hole diameter roundness is guaranteed to be within 0.02 mm. Improved perpendicularity of the product's inner cavity to the end face and improved inner hole roundness provide a good benchmark for subsequent VVT stator machining. By clamping the inner hole and bringing it closer to the end face, a high pass rate can be guaranteed with a single clamping, increasing machining efficiency by 30%. Attached Figure Description
[0008] Figure 1 This is a schematic diagram of the product structure of this utility model.
[0009] Figure 2 This is a schematic diagram of the structure of this utility model.
[0010] In the diagram: 1. Product; 2. Upper forming mold; 3. Positioning mandrel; 4. Female forming mold; 5. Lower forming outer mold; 6. Lower forming inner mold; 7. Forming mandrel; 101. First through hole; 102. Inner cavity; 103. End face; 201. Stepped hole; 401. First guide section; 601. Second through hole; 701. Second guide section. Detailed Implementation
[0011] The present invention will be further described below with reference to the accompanying drawings.
[0012] See Figure 1-2 The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art. They are not intended to limit the scope of this invention and therefore lack substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of this invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of this invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this invention.
[0013] Example 1: A forming mold for a powder metallurgy VVT stator, referenced Figure 1 , Figure 2The product 1 is horizontally placed on the upper end of the shaping mandrel 7. The product 1 has a ring structure. The outer ring of the ring structure is a chain tooth, and the inner ring of the ring structure is provided with four bosses evenly distributed around the circumference. Each boss has a first through hole 101 on its top surface. The inner arc surfaces of the four bosses are on the same circle, and the inner arc surfaces of the four bosses form the inner hole of the product 1. The lower part of the shaping mandrel 7 is provided with a shaping inner lower mold 6, a shaping outer lower mold 5, and a shaping female mold 4 in sequence from the inside to the outside. The inner lower die 6 is mounted on the worktable of the press via a lower die base. Four second through holes 601 are evenly distributed around the circumference on the top surface of the inner lower die 6. The second through holes 601 correspond one-to-one with the first through holes 101. A forming upper die 2 is provided above the product 1. Four stepped holes 201 are evenly distributed around the circumference on the top surface of the forming upper die 2. A positioning mandrel 3 is provided in the stepped hole 201. The small end of the positioning mandrel 3 is located in the corresponding first through hole 101. This invention employs four positioning mandrels of equal length. The small end of each positioning mandrel has the same size as the first through hole. The positioning mandrels are fixed by the upper forming mold via a bottom flange. The lower forming mold has four second through holes for engagement with the positioning mandrels during mold closing. During forming, the product is manually placed into the mold cavity guide section. Because the positioning mandrels protrude from the bottom surface of the upper forming mold, as the upper forming mold descends, before the bottom surface of the upper forming mold contacts the top surface of the product, the four positioning mandrels first contact and simultaneously enter the first through hole of the product. Therefore, under the radial action of the four positioning mandrels, the top surface of the product will contact the forming mandrels. Maintaining a vertical entry into the forming section of the mold cavity ensures uniform extrusion and plastic deformation of the product, guaranteeing its perpendicularity, hole diameter, and uniform shaping amount throughout the cavity. This solves the shaping and positioning problem for VVT stator products and avoids tilting issues when the product enters the forming section from the guide section. The product's perpendicularity can be achieved within 0.02 mm, and the hole diameter roundness is guaranteed to be within 0.02 mm. Improved perpendicularity of the product's inner cavity to the end face and improved inner hole roundness provide a good benchmark for subsequent VVT stator machining. By clamping the inner hole and bringing it closer to the end face, a high pass rate can be guaranteed with a single clamping, increasing machining efficiency by 30%.
[0014] Example 2: Based on Example 1, the upper forming mold 2 is a first-step shaft, with its small end face fitting with the top surface of the product 1. The lower forming mold 4 has a second-step hole, the small end of which contacts the lower forming mold 5, and the large end of which has a first guide section 401 that contacts the outer ring of the product 1. This invention uses a second-step hole within the lower forming mold, with the large end of the second-step hole having a first guide section that contacts the outer ring of the product, guiding the product from the guide section into the forming section.
[0015] Example 3: Based on Example 2, the upper part of the shaping mandrel 7 is provided with a second guide section 701, which contacts the inner hole of the product 1. This utility model employs a second guide section on the upper part of the shaping mandrel, which contacts the inner hole of the product, guiding the product from the guide section into the forming section.
[0016] Example 4: Based on Example 2, the upper forming die 2 has a first central hole at its center. The through hole corresponds to the outer diameter of the forming mandrel 7. The top surface of the upper forming die 2 is connected to a flange, an upper die base, and a press slide block in sequence. The flange has a second central hole at its center, which communicates with the first central hole. The flange limits the large end face of the positioning mandrel 3. This invention uses a flange connected to the top surface of the upper forming die, with the second central hole at the center of the flange communicating with the first central hole at the center of the upper forming die. The flange limits the large end face of the positioning mandrel.
[0017] The above-described embodiments are merely preferred embodiments of this utility model. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.
Claims
1. A forming mold for a powder metallurgy VVT stator, comprising a product (1) horizontally placed on the upper end of a forming mandrel (7), the product (1) having an annular structure, the outer ring of the annular structure having chain teeth, the inner ring of the annular structure having four bosses evenly distributed around the circumference, each boss having a first through hole (101) on its top surface, the inner arc surfaces of the four bosses being on the same circle, the inner arc surfaces of the four bosses forming the inner hole of the product (1), characterized in that: The lower part of the shaping mandrel (7) is provided with a shaping inner lower mold (6), a shaping outer lower mold (5), and a shaping female mold (4) in sequence from the inside to the outside. The top surface of the shaping inner lower mold (6) is provided with four second through holes (601) evenly distributed around the circumference. The second through holes (601) are arranged in a one-to-one correspondence with the first through holes (101). The upper part of the product (1) is provided with a shaping upper mold (2). The top surface of the shaping upper mold (2) is provided with four stepped holes (201) evenly distributed around the circumference. The step holes (201) are provided with a positioning mandrel (3). The small end of the positioning mandrel (3) is located in the corresponding first through hole (101).
2. The forming mold for a powder metallurgy VVT stator according to claim 1, characterized in that: The upper forming mold (2) is a first stepped shaft, and the small end face of the first stepped shaft is in contact with the top surface of the product (1); the lower forming mold (4) is provided with a second stepped hole, the small end of the second stepped hole is in contact with the lower forming mold (5), and the large end of the second stepped hole is provided with a first guide section (401), which is in contact with the outer ring of the product (1).
3. The forming mold for a powder metallurgy VVT stator according to claim 2, characterized in that: The upper part of the shaping mandrel (7) is provided with a second guide section (701), which contacts the inner hole of the product (1).
4. The forming mold for a powder metallurgy VVT stator according to claim 2, characterized in that: The upper forming mold (2) has a first central hole at its center. The through hole is arranged in accordance with the outer diameter of the forming mandrel (7). The top surface of the upper forming mold (2) is connected to a flange. The center of the flange has a second central hole. The second central hole communicates with the first central hole. The flange limits the large end face of the positioning mandrel (3).