A type of flat wire hair clip double bending forming mold

Abstract

This invention discloses a secondary bending forming mold for flat wire hair clips, belonging to the field of flat wire motor manufacturing technology. It solves the problem of the lack of a mechanism in the prior art for bending the straight section of a one-time formed hair clip. The mold includes a positioning base plate, a first fixed mold, a convex fixed mold, a concave moving mold, a first moving mold, and two forming sliding top blocks. This invention transfers the forming part of the one-time formed hair clip from the top triangular area to the straight section area of ​​the two legs. Through the cooperation of the concave moving mold and the two forming sliding top blocks, the straight section is bent at a specific first bending forming surface, thereby solving the stress release and springback problem caused by stamping in the triangular area. This effectively and reliably controls the height dimension of the hair clip crown end, meeting the design accuracy requirements.

Description

Technical Field

[0001] This invention relates to the field of flat wire motor manufacturing technology, specifically to a flat wire hairpin secondary bending forming mold. Background Technology

[0002] The existing hairpin end expansion forming process of new energy flat wire motor stators generally adopts a stamping structure. Specifically, this process uses a set of hairpin secondary forming molds. During the mold closing process, vertical or lateral pressure is directly applied to the triangular area at the top of the hairpin after the first forming. Through the extrusion action of the mold surface, the triangular area is forced to undergo plastic deformation, thereby realizing the secondary bending and expansion of the hairpin end.

[0003] However, this method of bending and forming in the triangular region has significant drawbacks. Due to the irregular structure and complex geometry of the triangular region, the stress distribution in this area is extremely uneven during stamping, easily generating highly concentrated internal stress. When the forming pressure is removed and the mold is opened, the inherent elasticity of the hairpin material causes it to spring back. This springback after stress release is difficult to accurately compensate for and control through mold design, resulting in large fluctuations in the height of the "crown end" (i.e., the top contour after forming) of the formed hairpin, which easily exceeds the tolerance limit. Excessive height tolerance of the crown end directly affects the neatness of the stator winding ends and subsequent assembly, and is a key process problem restricting production yield and motor performance stability.

[0004] To address the aforementioned issues, existing technology has shifted the bending area of ​​hairpins: the secondary forming portion is moved from a difficult-to-control triangular area to the straight section of the two hairpin legs, which has a more regular shape and simpler stress distribution. Precise bending in this straight section results in a more uniform stress distribution, significantly reduced and more predictable material springback. (Reference) Figure 6 and Figure 7 Compared to traditional triangular region forming, the straight-section bending forming of the hairpin results in better shape consistency, and the height of the crown end can be effectively and stably controlled within the design range, thus meeting the manufacturing requirements of high-precision motors. Although this technical approach has been proposed and its superiority proven, existing technologies lack a mechanism for straight-section bending forming of hairpins after one-time forming. Summary of the Invention

[0005] To address the aforementioned shortcomings of the prior art, this invention provides a flat wire hair clip secondary bending forming mold, which solves the problem that the prior art lacks a mechanism for bending and forming the straight section of a one-time formed hair clip.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A secondary bending forming mold for a flat hair clip is provided, comprising: a positioning base plate; a first fixed mold, fixed on the positioning base plate, the first fixed mold having a convex fixed mold for fitting and placing the top triangular area of ​​the hair clip to be formed in one step; a concave movable mold, slidably disposed on the positioning base plate and opposite to the convex fixed mold, the concave surface of the concave movable mold for accommodating the convex fixed mold and contacting the bottom two straight sections of the hair clip to be formed in one step; a first movable mold, slidably disposed on the concave movable mold and used to cooperate with the first fixed mold to press the top triangular area of ​​the hair clip to be formed in one step, and the first movable mold having a first bending forming surface at the connection between the triangular area of ​​the hair clip to be formed in one step and the two straight sections; and two forming sliding top blocks, the two forming sliding top blocks being respectively located on the bottom two sides of the first fixed mold and symmetrically slidably disposed on the positioning base plate along the center line of the positioning base plate; the two forming sliding top blocks being used to cooperate with the concave movable mold to push the two straight sections to be bent and formed at the two first bending forming surfaces.

[0007] The beneficial effect of this solution is that it transfers the forming part of the one-piece hair clip from the top triangular area to the straight section area of ​​the two legs. Essentially, this transfer transforms an "irregular extrusion forming process in irregularly shaped areas" into a "conventional controllable bending process in straight section areas." Structurally, the mold achieves this process through the precise coordinated action of a concave moving die and two forming sliding top blocks symmetrically arranged along the centerline. During operation, the concave moving die moves towards the one-piece hair clip, its concave surface first accommodating and contacting the straight sections on both sides of the bottom of the hair clip; the two forming sliding top blocks move synchronously towards the center. Their cooperation does not involve simple stamping of the hair clip, but rather applies a concentrated, controllable bending force to the straight sections at a specifically designed first bending forming surface, causing precise plastic bending. Based on this "part transfer" and "action transformation," this solution fundamentally overcomes the inherent technical difficulties of stamping in triangular areas. Due to the complex geometry of the triangular region, the stress distribution during stamping is extremely uneven, resulting in high and unpredictable residual stress within the material after forming. This inevitably leads to significant and irregular elastic rebound after the external force is removed, which is the main reason for the crown end height dimensional deviation. This solution, however, involves directional bending in the straight section region, concentrating stress application and releasing it evenly, resulting in minimal material springback and predictable height. Therefore, this mold can effectively and reliably control the height of the hairpin crown end within a strict tolerance zone, significantly reducing the probability of product deviation. This fully meets the design requirements of high-precision flat wire motor stators for winding end dimensions, improving production yield and product consistency.

[0008] Furthermore, the positioning base plate is symmetrically inclined with molding sliding guide grooves on both sides of the bottom of the first fixed mold, and the two molding sliding top blocks are respectively slidably disposed in the two molding sliding guide grooves. By symmetrically setting inclined molding sliding guide grooves on the positioning base plate, a precise and stable motion trajectory is provided for the two molding sliding top blocks, which facilitates the external driving components (hydraulic cylinder, air cylinder, electric cylinder) to drive the molding sliding top blocks.

[0009] Furthermore, each of the two forming sliding top blocks has a second bending forming surface on the top side near the concave moving mold. The bending forming of the straight section is completed by the cooperation of the first bending forming surface and the second bending forming surface, forming a more optimized force application mode, which may make the bending process smoother, the bending angle more precise, and improve the forming quality.

[0010] Furthermore, both the first and second bending forming surfaces are arc-shaped bending surfaces. The arc-shaped transition surface can apply a more uniform force to the straight section of the copper wire hair clip during the bending process.

[0011] Furthermore, the adjacent surfaces of the first fixed mold and the first moving mold are fitted with the top triangular area of ​​the hair clip formed in one step. The fitting setting ensures that the top triangular area of ​​the hair clip is firmly clamped and positioned during the bending of the straight section, preventing it from shifting or twisting, ensuring the accuracy of the bending position of the straight section, and making the forming result stable.

[0012] Furthermore, a positioning slider is provided on the side of the first moving mold away from the concave moving mold, and the positioning slider is slidably mounted on the positioning base plate. The positioning slider, being away from the concave moving mold and slidably mounted with the positioning base plate, optimizes the connection path between the external drive mechanism and the first moving mold in terms of power transmission. Since the positioning slider is located at the rear end of the first moving mold, it provides a direct point of action for external drive components such as cylinders and hydraulic cylinders. The drive mechanism can directly push or pull the positioning slider along the mold's axial direction or a preset direction, thereby efficiently and linearly transmitting power to the first moving mold. This connection method avoids the need for indirect or complex transmission through the concave moving mold, simplifies the drive chain, and improves transmission efficiency and response accuracy. Simultaneously, the positioning slider design achieves a high degree of uniformity in motion reference. The direct mounting and sliding reference surfaces of the three core moving components—the positioning slider, the concave moving mold, and the two forming sliding top blocks—are all unified on the main structure of the positioning base plate. This means that the guiding accuracy and relative positional relationship of all motion pairs depend on the same high-precision machining and assembly reference. This "common-base" design fundamentally eliminates the cumulative errors in the dimensional chain and the superposition of geometric tolerances that may arise from inconsistent references among multiple components. This ensures extremely high geometric accuracy and repeatability in the motion coordination between the first moving mold and the concave moving mold, as well as between them and the forming sliding ejector block. In summary, the positioning slider not only achieves efficient and direct driving of the first moving mold, but also, by anchoring all moving parts to the same reference base plate, constructs a high-precision motion system with unified reference and controllable error. This is a crucial structural foundation for ensuring the final dimensional stability of the mold.

[0013] Furthermore, limit blocks are installed at the sliding connection ends of the concave moving mold and the positioning slider on the positioning base plate. Limit blocks are installed at the ends of the sliding paths of the concave moving mold and the positioning slider, achieving a crucial mechanical hard limit function. The working principle is that when the concave moving mold or the first moving mold moves towards the one-time forming hairpin under the action of the drive mechanism and completes the pressing or bending action, the endpoint of their movement stroke is not determined by the drive system's program or soft limit, but is ultimately determined by the physical obstruction of these rigidly installed limit blocks. This mechanical hard limit method provides a crucial protective effect. It can precisely and absolutely limit the final position and clamping force of the mold closing, fundamentally preventing excessive mold stroke due to drive system overshoot, control errors, or improper debugging, thus preventing excessive compression of the hairpin. Excessive compression can not only cause the hairpin's geometry to deviate from tolerances, but also damage or even break the fragile insulation layer on the copper wire surface due to excessive stress. Once the insulation layer is damaged, it will directly lead to a short circuit in the motor windings or a decline in electrical performance, resulting in product scrap. Therefore, these limit blocks are not simply markers of the travel end point, but key safety mechanisms to ensure product qualification rates. Through rigid mechanical interference, they set an insurmountable physical barrier for the precision bending and forming process, actively avoiding the risk of insulation layer damage caused by overvoltage. This directly and reliably protects the core quality (electrical insulation) of the product, enhancing the robustness and reliability of the entire production process.

[0014] Furthermore, a through slot is provided in the middle of the positioning base plate to provide connection channels between the external drive mechanism and the concave moving mold and the first moving mold, respectively. This through slot design offers several significant advantages. First, it forms a dedicated connection channel in the middle of the positioning base plate, providing a direct path for the external drive mechanism (such as the piston rod of a cylinder, the push rod of a hydraulic cylinder, or the shaft of an electric cylinder) to the concave moving mold and the first moving mold. This direct bottom connection makes the installation, connection, and debugging of the drive mechanism extremely convenient, eliminating the need for complex connecting brackets or steering mechanisms on the side of the mold, simplifying equipment integration. More importantly, compared to the traditional method of connecting the drive mechanism from the side of the mold, this bottom-through connection design offers fundamental space optimization benefits. When all drive components are connected from below the base plate, the side and top operating space of the mold is completely freed up, becoming open and unobstructed. This allows the robot or operator to move freely without being affected by any side connecting rods, pipes, or joints when picking up or placing one-time molding cards, achieving unobstructed handling. This not only improves the efficiency and reliability of automated loading and unloading, but also reduces the risk of interference or collisions during manual operation, while providing greater flexibility for the layout of molds in compact automated production lines. Attached Figure Description

[0015] Figure 1 This is a top view of a mold for forming a flat hair clip by secondary bending. Figure 2 A schematic diagram of the structure of a flat wire hair clip formed by a secondary bending forming mold and a single pressing forming process; Figure 3 A schematic diagram of the structure of a flat wire hair clip secondary bending forming mold in a state of applying force to a hair clip formed in the first stage; Figure 4 This is a cross-sectional view of the mold used for installing a one-piece hair clip; Figure 5 A cross-sectional view of the mold used for bending a hair clip in a single molding process; Figure 6 This is a schematic diagram of the structure of a one-piece molded hair clip; Figure 7 This is a schematic diagram of the structure of a hair clip after it has been formed by bending it twice from a single molding process. The components are: 1. Forming sliding top block; 2. Forming sliding guide groove; 3. First fixed mold; 4. Positioning base plate; 5. First moving mold; 6. Convex fixed mold; 7. Concave moving mold; 8. One-time forming hair clip. Detailed Implementation

[0016] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0017] This embodiment provides a flat wire hair clip secondary bending forming mold, which solves the problem in the prior art of lacking a mechanism for bending the straight section of a one-time formed hair clip 8. (Refer to...) Figure 1 It includes a positioning base plate 4, a first fixed mold 3, a convex fixed mold 6, a concave moving mold 7, a first moving mold 5, and two forming sliding top blocks 1.

[0018] Specifically, the first fixed mold 3 is fixed on the positioning base plate 4, and the first fixed mold 3 is provided with a convex fixed mold 6 for fitting and placing the top triangular area of ​​the one-time molded hair clip 8. The adjacent surfaces of the first fixed mold 3 and the first moving mold 5 are fitted with the surface of the top triangular area of ​​the one-time molded hair clip 8. The fitting arrangement ensures that the top triangular area of ​​the hair clip is firmly clamped and positioned during the bending of the straight section, preventing it from shifting or twisting, ensuring the accuracy of the bending position of the straight section, and making the molding result stable.

[0019] Specifically, the concave moving mold 7 is slidably set on the positioning base plate 4 and is set opposite to the convex fixed mold 6. The concave surface of the concave moving mold 7 is used to accommodate the convex fixed mold 6 and to contact the straight sections on both sides of the bottom of the one-time forming hair clip 8.

[0020] Specifically, the first moving mold 5 is slidably mounted on the concave moving mold 7 and is used to cooperate with the first fixed mold 3 to press the top triangular area of ​​the one-time formed hair clip 8. The first moving mold 5 has a first bending forming surface at the triangular area of ​​the one-time formed hair clip 8 and the connection between the two straight sections. The top of each of the two forming sliding top blocks 1 near the concave moving mold 7 has a second bending forming surface. Both the first and second bending forming surfaces are arc-shaped bending surfaces. The bending forming of the straight section is completed by the cooperation of the first and second bending forming surfaces, forming a more optimized force application mode, which may make the bending process smoother, the bending angle more precise, and improve the forming quality.

[0021] Specifically, two forming sliding ejector blocks 1 are located on the bottom sides of the first fixed mold 3 and are symmetrically slidably disposed on the positioning base plate 4 along the center line of the positioning base plate 4. The two forming sliding ejector blocks 1 are used to cooperate with the concave moving mold 7 to push the two straight sections to bend and form at the two first bending forming surfaces. As a structure in which the forming sliding ejector blocks 1 are slidably disposed on the positioning base plate 4, the positioning base plate 4 is symmetrically inclined with forming sliding guide grooves 2 on both sides of the bottom of the first fixed mold 3, and the two forming sliding ejector blocks 1 are respectively slidably disposed in the two forming sliding guide grooves 2. By symmetrically providing inclined forming sliding guide grooves 2 on the positioning base plate 4, a precise and stable motion trajectory is provided for the two forming sliding ejector blocks 1, which facilitates the external driving components (hydraulic cylinder, air cylinder, electric cylinder) to drive the forming sliding ejector blocks 1.

[0022] As a further embodiment, a positioning slider is provided on the side of the first moving mold 5 away from the concave moving mold 7. The positioning slider has a rectangular structure and is slidably mounted on the positioning base plate 4. The positioning slider is away from the concave moving mold 7 and is slidably mounted on the positioning base plate 4. This not only facilitates the external driving mechanism to provide power to the first moving mold 5, but also ensures that the mounting surface references of the first moving mold 5, the concave moving mold 7, and the forming sliding top block 1 are all on the positioning base plate 4, thereby unifying the references and reducing dimensional and positional errors.

[0023] As a further embodiment, limit blocks are provided on the positioning base plate 4 at the sliding connection ends of the concave moving mold 7 and the positioning slider, respectively. The limit blocks at the ends of the sliding paths of the concave moving mold 7 and the positioning slider can act as mechanical hard limiters, effectively preventing excessive squeezing of the copper wire by the moving mold during mold closing, avoiding damage to the insulation layer on the surface of the copper wire due to excessive pressure, and thus protecting the product.

[0024] As a further embodiment, the positioning base plate 4 is provided with a through slot in the middle for providing connection channels between the external driving mechanism and the concave moving mold 7 and the first moving mold 5, respectively. This through slot provides a connection channel for the external driving mechanism (such as a cylinder, hydraulic cylinder, electric cylinder, etc.), which not only facilitates connection, but also, since the connection is from the bottom of the positioning base plate 4, compared to connecting the concave moving mold 7 or the first moving mold 5 from the side of the mold, the connection via the through slot does not affect the placement and removal of the one-time molding hair clip 8.

[0025] The beneficial effects of this plan are: This solution transfers the forming part of the one-piece hair clip 8 from the top triangular area to the straight section area of ​​the two legs. Through the cooperation of the concave moving mold 7 and the two forming sliding top blocks 1, the straight section is bent at a specific first bending forming surface, thus solving the stress release and springback problem caused by stamping in the triangular area. This effectively and reliably controls the height dimension of the hair clip crown end, meeting the design accuracy requirements. Simultaneously, by covering and sliding the first moving mold 5 onto the concave moving mold 7, the two can slide relative to each other, respectively fitting the triangular area and the straight section of the one-piece hair clip 8, and facilitating the movement of the concave moving mold 7 relative to the first moving mold 5 to bend and form the straight section.

[0026] The working principle of this solution is as follows: refer to Figure 2 and Figure 4 The one-piece hair clip 8 is placed on the convex fixed mold 6. An external drive mechanism moves the concave moving mold 7 and the first moving mold 5, pressing the triangular area at the top of the one-piece hair clip 8 between the first fixed mold 3 and the first moving mold 5, and bringing the straight sections on both sides of the one-piece hair clip 8 into contact with the concave moving mold 7. (The rest of the text is a reference to a different topic.) Figure 3 and Figure 5 Keeping the first moving mold 5 fixed, the two forming sliding top blocks 1 move in the forming sliding guide groove 2, respectively pressing the straight sections on both sides of the one-time forming hair clip 8 and applying force to form them. The two forming sliding top blocks 1 drive the concave moving mold 7 to move synchronously, so that the two straight sections are bent and formed under the first bending forming surface of the first moving mold 5.

Claims

1. A mold for secondary bending and forming of flat wire hair clips, characterized in that, include: Positioning base plate (4); The first fixed mold (3) is fixed on the positioning base plate (4). The first fixed mold (3) is provided with a convex fixed mold (6) for fitting and placing the top triangular area of ​​the one-time molded hair clip (8). A concave moving mold (7) is slidably disposed on the positioning base plate (4) and opposite to the convex fixed mold (6). The concave surface of the concave moving mold (7) is used to accommodate the convex fixed mold (6) and to contact the straight sections on both sides of the bottom of the one-time forming hair clip (8). The first moving mold (5) is slidably disposed on the concave moving mold (7) and is used to cooperate with the first fixed mold (3) to press the top triangular area of ​​the one-time molded hair clip (8). The first moving mold (5) is provided with a first bending forming surface at the triangular area of ​​the one-time molded hair clip (8) and the connection between the two straight sections. Two forming sliding top blocks (1) are respectively located on the bottom sides of the first fixed mold (3) and symmetrically slidably arranged on the positioning base plate (4) along the center line of the positioning base plate (4); the two forming sliding top blocks (1) are used to cooperate with the concave moving mold (7) to push the two straight sections to bend and form at the two first bending forming surfaces.

2. The flat wire hair clip secondary bending forming mold according to claim 1, characterized in that, The positioning base plate (4) is symmetrically inclined with forming sliding guide grooves (2) on both sides of the bottom of the first fixed mold (3), and the two forming sliding top blocks (1) are respectively slidably arranged in the two forming sliding guide grooves (2).

3. The flat wire hair clip secondary bending forming mold according to claim 1, characterized in that, The top of each of the two forming sliding blocks (1) near the concave moving mold (7) is provided with a second bending forming surface.

4. The flat wire hair clip secondary bending forming mold according to claim 3, characterized in that, Both the first bending forming surface and the second bending forming surface are arc-shaped bending surfaces.

5. The flat wire hair clip secondary bending forming mold according to claim 1, characterized in that, The adjacent surfaces of the first fixed mold (3) and the first moving mold (5) are in contact with the top triangular area of ​​the one-time molded hair clip (8).

6. The flat wire hair clip secondary bending forming mold according to claim 1, characterized in that, The first moving mold (5) is provided with a positioning slider on the side away from the concave moving mold (7), and the positioning slider is slidably disposed on the positioning base plate (4).

7. The flat wire hair clip secondary bending forming mold according to claim 6, characterized in that, Limit blocks are provided on the positioning base plate (4) at the sliding connection ends of the concave moving mold (7) and the positioning slider, respectively.

8. The flat wire hair clip secondary bending forming mold according to claim 1, characterized in that, The positioning base plate (4) has a through groove in the middle for providing a connection channel between the external drive mechanism and the concave moving mold (7) and the first moving mold (5).

Images