Thermoforming die structure for thin parts

Abstract

This invention provides a thermoforming mold structure for thin parts. The upper mold core is divided into three parts: a fixed upper mold core and two movable upper mold cores. An elastic reset member and a limiting part offset the movable upper mold cores from their theoretical positions by a certain displacement distance. Before the upper and lower mold surfaces are fully pressed together, a driving wedge and a driven wedge pull the movable upper mold cores to the forming position. This invention solves the problems of easy cracking and severe wear of insert sidewalls in existing thermoforming molds. It allows thin sheet metal to have a large forming gap at the vertical wall during the forming process. Furthermore, during forming, only the convex corner of the movable upper mold core contacts the thin sheet metal, significantly reducing the friction between the thin sheet metal and the mold, and preventing cracking of the vertical wall during thermoforming. It is particularly suitable for stamping thermoformed parts with small draft angles and large forming depths.

Description

Technical Field

[0001] The invention relates to the technical field of thermoforming moulds, in particular to a thermoforming mould structure for thin parts. Background Art

[0002] like Figure 1 , Figure 2 As shown, it is a schematic structural diagram of an existing thermoforming mold 10, wherein the thermoforming mold 10 comprises an upper mold base 11, a lower mold base 12, an upper mold core 13 and a lower mold core 14, wherein the upper mold core 13 is arranged on the bottom side of the upper mold base 11 to serve as an upper insert of the mold and is formed with a concave profile, and the lower mold core 14 is arranged on the top side of the lower mold base 12 to serve as a lower insert of the mold and is formed with a convex profile; Figure 2 As shown, the thermoforming mold 10 defines a forming distance t through the concave profile of the upper mold core 13 and the convex profile of the lower mold core 14, which is used to Figure 2 The thin sheet material 200 is formed by hot pressing as Figure 1 The thin part 20 is shown.

[0003] It is worth noting that in the structural design of the general hot forming mold 10, the gap width of the forming distance t is fixed, that is, when the upper mold base 11 and the lower mold base 12 are pressed to form the thin plate 200, the forming is performed with the same gap (forming distance t) of the material thickness from the beginning to the end of the forming process; such a mold structural design will result in a large contact area between the vertical part 15 on the molding surface and the thin plate 200, and a large friction force will be generated during the upper and lower pressing process; thus, Figure 1 , Figure 2 The thermoforming mold 10 shown is suitable for a thin part 20 with a shallow forming depth and a large draft angle of the vertical surface portion 15 and good formability.

[0004] However, the existing hot forming mold 10 with the same forming distance t is prone to cracking when processing parts with a small draft angle and a small forming radius on the opposing surface part 15, especially for thin plate parts (such as steel plate materials below 1.2 mm). This brings considerable difficulties to the design and development of parts and the debugging and production of molds.

[0005] In addition, the aforementioned Figure 1 , Figure 2 The existing thermoforming mold 10 structure shown also has the problem of causing great wear to the mold insert surface (such as the concave surface and the convex surface) during the forming process, thereby greatly reducing the service life of the insert, which also needs further improvement. Summary of the invention

[0006] In view of the above situation, the present invention provides a hot forming mold structure for thin parts. By allowing the molding gap between the molding surfaces of the upper mold core and the lower mold core of the mold to change with the molding process of the thin plate, the problem that thin parts with small draft angles and small molding radii on the vertical parts are prone to cracking under conventional molding methods is solved. At the same time, the problem of reduced insert service life due to wear of the insert surface is also solved.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is to provide a thermoforming mold structure for thin parts, wherein the thermoforming mold comprises an upper mold base, a lower mold base, an upper mold core arranged on the bottom side of the upper mold base, and a lower mold core arranged on the top side of the lower mold base, wherein the bottom surface of the upper mold core and the top surface of the lower mold core are sequentially formed into an upper model surface and a lower model surface of the thermoforming mold, and there is a vertical distance between the vertical surface portions of the upper model surface and the lower model surface; wherein the thermoforming mold also includes The movable cam and the driving cam; the upper die seat, the bottom surface of which is provided with limiting parts on the opposite sides of the upper die core; the upper die core comprises a fixed upper die core and two movable upper die cores; the fixed upper die core is fixedly arranged on the bottom surface of the upper die seat, the two movable upper die cores are located on the opposite sides of the fixed upper die core, and can be displaced between the limiting parts of the upper die seat and the fixed upper die core on the bottom surface of the upper die seat, the fixed upper die core is connected with the bottom surface of the movable upper die core to form the upper mold surface; the movable upper die core An elastic reset member is provided between the fixed upper mold core, and the movable upper mold core is limited by the elastic reset member to reset against the limiting portion of the upper mold base in an unstressed state, and the movable upper mold core has a displacement distance S between the limiting portion and the elastic reset member; the driven cam is fixedly provided on the outer side of the movable upper mold core away from the fixed upper mold core; the lower side of the outer end of the driven cam is provided with a driven inclined surface inclined from outside to inside; the driving cam is fixedly provided on the top surface of the lower mold base and is located The lower mold core is on opposite sides; the inner side of the top end of the driving wedge is provided with a driving inclined surface inclined from outside to inside, and the driving inclined surface is arranged opposite to the driven inclined surface and the inclination angles match; the vertical spacing of the thermoforming mold is greater than or equal to the sum of the part thickness and the displacement distance S of the movable upper mold core; the upper model surface and the lower model surface are pressed together, and the driving wedge drives the driven wedge to pull the two movable upper mold cores to move toward the fixed upper mold core and compress and change the vertical spacing to be equal to the part thickness.

[0008] In an embodiment of the present invention, a recess is formed on the bottom surface of the upper mold base, the fixed upper mold core is fixed in the recess, and the two movable upper mold cores are displaceably disposed in the recess between the limiting portion of the upper mold base and the fixed upper mold core.

[0009] In an embodiment of the present invention, the limiting portion of the upper die seat is formed as a stroke limiting block, the stroke limiting block is arranged on the bottom surface of the upper die seat around the recess, and the end of the stroke limiting block extends into the opening range of the recess.

[0010] In an embodiment of the present invention, the elastic return member of the upper mold core is a transversely arranged spring; a groove portion with an opening that can be matched is recessed on the side wall corresponding to the fixed upper mold core and the movable upper mold core; the two ends of the spring are respectively accommodated in the groove portion of the fixed upper mold core and the groove portion of the movable upper mold core.

[0011] In an embodiment of the present invention, the driving bevel has an inclination angle α; the driving bevel is offset against the driven bevel, and there is a pressing stroke distance H between the upper model surface and the lower model surface; the pressing stroke distance H and the displacement distance S of the movable upper mold core are obtained according to the relationship H=S*cot(α).

[0012] In an embodiment of the present invention, the movable upper mold core is movably connected to the bottom surface of the upper mold base through a slide rail mechanism.

[0013] In an embodiment of the present invention, the fixed upper mold core is fixedly connected to the bottom surface of the upper mold base by threads.

[0014] The present invention adopts the above technical solution, so it has the following beneficial effects:

[0015] (1) The present invention divides the upper mold core into three parts: a fixed upper mold core and two movable upper mold cores, and uses an elastic reset part (spring) and a limit part (travel limit block) to deviate the movable upper mold core from the theoretical position by a certain displacement distance S. Before the upper mold surface and the lower mold surface are completely pressed together, the driving wedge and the driven wedge pull the movable upper mold core to the forming position. With this structure, the thin plate can have a larger forming gap (vertical surface spacing D) at the vertical wall during the forming process, and during the forming process, only the convex corner position of the movable upper mold core contacts the thin plate, which greatly reduces the friction between the thin plate and the mold, and can not only avoid the cracking of the vertical wall of the thermoformed part during the forming process, but also avoid the cracking of the thermoformed part with a small vertical wall draft angle and a large forming depth.

[0016] (2) Through the aforementioned technical solution of the present invention, while reducing the friction between the thin plate and the mold, it can also effectively reduce the wear of the parts on the vertical wall of the mold insert due to the friction, thereby increasing the service life of the insert.

[0017] (3) The thermoforming mold structure for thin parts of the present invention is safe and reliable, which overcomes the disadvantages of easy cracking of parts and severe wear of the side wall of the insert when the conventional thermoforming mold is used to stamp parts, greatly improves the production stability and the service life of the insert, and reduces the production and mold maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structural cross-section of an existing thermoforming mold.

[0019] Figure 2 The present invention is a schematic cross-sectional view of the structure of an existing thermoforming mold before the upper and lower molds are completely pressed together.

[0020] Figure 3 It is a schematic cross-sectional view of the structure of the thermoforming die structure for thin parts of the present invention before the contact of the wedge.

[0021] Figure 4 It is a schematic cross-sectional view of the structure of the thermoforming die structure for thin parts of the present invention when the wedge is in contact.

[0022] Figure 5 The present invention is a schematic cross-sectional view of the structure of the thermoforming mold structure for thin parts in a state where the upper and lower molds are completely pressed together.

[0023] The corresponding relationship between the reference numerals and the components is as follows:

[0024] Thermoforming mold 10; upper mold base 11; lower mold base 12; upper mold core 13; lower mold core 14; vertical surface part 15; thin part 20; thin plate material 200; forming distance t; upper mold base 30; limiting part 31; recess 32; lower mold base 40; upper mold core 50; upper model surface 501; fixed upper mold core 51; movable upper mold core 52; elastic reset part 53; lower mold core 60; lower model surface 601; driven wedge 70; driven inclined surface 71; driving wedge 80; driving inclined surface 81; vertical surface spacing D; displacement distance S; inclination angle α; pressing stroke distance H. DETAILED DESCRIPTION

[0025] To facilitate understanding of the present invention, the following description is provided in conjunction with the accompanying drawings and embodiments.

[0026] See also Figures 3 to 5 The present invention provides a thermoforming mold structure for thin parts, wherein the thermoforming mold includes an upper mold base 30, a lower mold base 40, an upper mold core 50, a lower mold core 60, a driven cam 70 and a driving cam 80.

[0027] like Figure 3As shown, the upper mold core 50 is arranged on the bottom side of the upper mold base 30, and the lower mold core 60 is arranged on the top side of the lower mold base 40; the bottom surface of the upper mold core 50 and the top surface of the lower mold core 60 are sequentially formed into the upper model surface 501 and the lower model surface 601 of the thermoforming mold.

[0028] In the embodiment of the present invention, Figures 3 to 5 As shown, the cross-sectional shape of the upper model surface 501 and the lower model surface 601 of the present invention is approximately Ω, and the cross-sectional shape is formed into a plane on both sides, and a ㄇ-shaped concave-convex fit is formed in the middle part, so that the inner concave part of the upper model surface 501 forms two vertical surfaces, and the outer convex part of the lower model surface 601 forms another two vertical surfaces correspondingly, so that two vertical gaps are formed after the upper model surface 501 and the lower model surface 601 are pressed together, and there is a vertical distance D between the vertical surfaces of the vertical gaps. It should be understood that the cross-sectional shape of the upper model surface 501 and the lower model surface 601 of the present invention is not limited to the aforementioned embodiment, and the thermoforming mold of the present invention is suitable for other thin parts 20 with concave-convex structures and requiring forming vertical walls.

[0029] Furthermore, if Figures 3 to 5 As shown, the direction of the thermoforming mold toward both sides is defined as its outer side, and the direction toward the mold core is defined as its inner side. The bottom surface of the upper mold base 30 is provided with limiting portions 31 on opposite sides of the upper mold core 50 . The upper mold core 50 includes a fixed upper mold core 51 and two movable upper mold cores 52; the fixed upper mold core 51 is fixedly arranged on the bottom surface of the upper mold base 30, and the two movable upper mold cores 52 are located on opposite sides of the fixed upper mold core 51, and can be displaced on the bottom surface of the upper mold base 30 between the limiting portion 31 of the upper mold base 30 and the fixed upper mold core 51, and the bottom surfaces of the fixed upper mold core 51 and the movable upper mold core 52 are connected to form the upper mold surface 501; an elastic reset member 53 is arranged between the movable upper mold core 52 and the fixed upper mold core 51, and the movable upper mold core 52 is limited by the elastic reset member 53 to reset against the limiting portion 31 of the upper mold base 30 in an unstressed state, and the movable upper mold core 52 has a displacement distance S between the limiting portion 31 and the elastic reset member 53.

[0030] The driven cam 70 is fixedly arranged on the outer side of the movable upper mold core 52 away from the fixed upper mold core 51; a driven inclined surface 71 inclined from outside to inside is arranged on the lower side of the outer end of the driven cam 70. The driving cam 80 is fixedly arranged on the top surface of the lower mold base 40 and located on opposite sides of the lower mold core 60; a driving inclined surface 81 inclined from outside to inside is arranged on the inner side of the top end of the driving cam 80, and the driving inclined surface 81 is arranged opposite to the driven inclined surface 71 and the inclination angles match.

[0031] Thereby, when the driving bevel 81 and the driven bevel 71 are not in contact, the vertical spacing D of the thermoforming mold is greater than or equal to the sum of the part thickness and the displacement distance S of the movable upper mold core 52; when the driving bevel 81 and the driven bevel 71 are sliding against each other, the movable upper mold core 52 is pulled by the driving bevel 80 to move toward the fixed upper mold core 51; when the upper model surface 501 and the lower model surface 601 are pressed against the thin plate material 200, the movable upper mold core 52 is pulled by the driving bevel 80 to press against the movable upper mold core 52, and the vertical spacing D is equal to the part thickness.

[0032] In the embodiment of the present invention, Figure 1 As shown, a concave portion 32 is formed on the bottom surface of the upper die base 30, the fixed upper die core 51 is fixedly disposed in the concave portion 32, and the two movable upper die cores 52 are displaceably disposed in the concave portion 32 between the limiting portion 31 of the upper die base 30 and the fixed upper die core 51. The limiting portion 31 of the upper die base 30 is formed as a stroke limiting block, which is disposed on the bottom surface of the upper die base 30 around the concave portion 32, and the end of the stroke limiting block extends to the opening range of the concave portion 32.

[0033] Thereby, the movable upper mold core 52 is limited by the travel limit block whose end exceeds the side wall of the recess 32, thereby ensuring the displacement distance S of the movable upper mold core 52. At the same time, by arranging the movable upper mold core 52 in the recess 32, the side wall of the recess 32 forms a second protective structure for limiting the displacement distance of the movable upper mold core 52, thereby avoiding the movable upper mold core 52 being improperly reset due to the influence of the elastic reset part 53.

[0034] In an embodiment of the present invention, the elastic return member 53 of the upper mold core 50 is a transversely arranged spring; the side walls corresponding to the fixed upper mold core 51 and the movable upper mold core 52 are recessed with grooves whose openings can be matched; the two ends of the spring are respectively accommodated in the grooves of the fixed upper mold core 51 and the movable upper mold core 52.

[0035] In the embodiment of the present invention, Figure 4 As shown, the driving inclined surface 81 has an inclination angle α; the driving inclined surface 81 is made to abut against the driven inclined surface 71, and there is a pressing stroke distance H between the upper mold surface 501 and the lower mold surface 601; the pressing stroke distance H and the displacement distance S of the movable upper mold core 52 are obtained according to the relationship H=S*cot(α).

[0036] In the embodiment of the present invention, the movable upper mold core 52 is movably connected to the bottom surface of the upper mold base 30 through a slide rail mechanism. Specifically, the slide rail mechanism may include but is not limited to the cooperation of a slide rail and a slider, a slide groove and a slide guide plate, or other forms of concave and convex fixing means that can slide relative to each other.

[0037] In the embodiment of the present invention, the fixed upper mold core 51 is fixedly connected to the bottom surface of the upper mold base 30 by means of threads. Specifically, the threaded fixing connection means includes fixing the fixed upper mold core 51 to the bottom surface of the upper mold base 30 by means of bolts or other means having threads and capable of screwing the fixed upper mold core 51 to the bottom surface of the upper mold base 30.

[0038] The above describes the specific structural embodiment of the thermoforming mold structure for thin parts of the present invention. Figures 3 to 5 As shown, the working principle of the thermoforming mold structure for thin parts of the present invention and the process of forming a thin plate 200 into a thin part 20 are explained.

[0039] like Figure 3 The figure shows a state of the thermoforming mold of the present invention in the process of the upper mold base 30 being driven downward by the upper slider of the press (not shown). At this time, the upper mold core 50 has contacted with the thin plate 200 and started to press down, but the driven wedge 70 and the driving wedge 80 are not in contact, and the two movable upper mold cores 52 are in the initial position and retreat from the fixed upper mold core 51 and abut against the limit portion 31; wherein, a gap is formed between the movable upper mold core 52 and the fixed upper mold core 51, and the distance of the gap is equivalent to the displacement distance S of the movable upper mold core 52, and the part thickness of the thin plate 200 is equivalent to Figure 2 The forming distance t of the medium-thin part 20 in the hot forming mold, and the vertical distance D formed between the vertical parts of the upper model surface 501 and the lower model surface 601 is equal to or equal to the total thickness (S+t) of the displacement distance S and the forming distance t. Figure 3 In this forming process, the vertical distance D is greater than the forming distance t, so that the movable upper mold core 52 only contacts the thin plate 200 with its convex R angle to generate friction, and there is enough space for the thin plate 200 to be compressed and deformed during the forming process.

[0040] like Figure 4 As shown in FIG. 1 , the state diagram of the lower press machine continues to move downward until the driven cam 70 just contacts the driving cam 80. At this time, the thin plate 200 has been basically formed in place, and the upper mold core 50 only has a pressing stroke distance H left; then, when the driving cam 80 pushes the driven cam 70 to move rapidly toward the fixed upper mold core 51 during the downward process of the press machine, it also drives the two movable upper mold cores 52 to move toward the fixed upper mold core 51, as shown in FIG. Figure 5As shown, when the press machine descends to the closing height of the thermoforming mold, the upper mold surface 501 and the lower mold surface 601 are compressed to a part thickness (i.e., the forming distance t between the upper and lower mold surfaces), so that the thin plate 200 is formed into a thin part 20.

[0041] Finally, after the press pressure is maintained, the upper die base 30 is driven upward by the upper slider, and the elastic reset member 53 and the limit portion 31 of the upper die base 30 force the two movable upper die cores 52 to reset; when the press reaches the top dead point and completes the loading, the press slider moves downward again to complete the molding cycle of the next thin part 20.

[0042] In summary, the present invention realizes a thermoforming mold with safe and reliable operation through the aforementioned thermoforming mold structure for thin parts, and indeed overcomes the disadvantages of easy cracking of parts and severe wear of the side walls of inserts when stamping parts with conventional thermoforming molds. It also greatly improves the stability of the production of thin parts 20 and the service life of the inserts of the forming mold, and reduces the production and mold maintenance costs.

[0043] The present invention is described in detail above in conjunction with the accompanying drawings and embodiments. A person skilled in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation of the present invention, and the scope of protection of the present invention shall be defined by the scope of the attached claims.

Claims

1. A thermoforming mold structure for thin parts, the thermoforming mold comprising an upper mold base, a lower mold base, an upper mold core arranged on the bottom side of the upper mold base, and a lower mold core arranged on the top side of the lower mold base, the bottom surface of the upper mold core and the top surface of the lower mold core are sequentially formed into an upper mold surface and a lower mold surface of the thermoforming mold, and there is a vertical distance between the vertical surface parts of the upper mold surface and the lower mold surface; characterized in that, The thermoforming die also includes a driven cam and a driving cam; wherein: The upper die seat has a bottom surface provided with limiting portions on opposite sides of the upper die core; The upper mold core comprises a fixed upper mold core and two movable upper mold cores; the fixed upper mold core is fixedly arranged on the bottom surface of the upper mold base, the two movable upper mold cores are located on opposite sides of the fixed upper mold core, and can be displaced between the limiting portion of the upper mold base and the fixed upper mold core on the bottom surface of the upper mold base, the fixed upper mold core and the bottom surface of the movable upper mold core are connected to form the upper mold surface; an elastic reset member is arranged between the movable upper mold core and the fixed upper mold core, the movable upper mold core is limited by the elastic reset member to reset against the limiting portion of the upper mold base in an unstressed state, and the movable upper mold core has a displacement distance S between the limiting portion and the elastic reset member; The driven cam is fixedly arranged on the outer side of the movable upper die core away from the fixed upper die core; the lower side of the outer end of the driven cam is provided with a driven inclined surface inclined from the outside to the inside; The driving inclined wedge is fixedly arranged on the top surface of the lower die seat and located on two opposite sides of the lower die core; a driving inclined surface inclined from outside to inside is arranged on the inner side of the top end of the driving inclined wedge, and the driving inclined surface is arranged opposite to the driven inclined surface and the inclination angles match; The vertical spacing of the thermoforming mold is greater than or equal to the sum of the thickness of the part and the displacement distance S of the movable upper mold core; the upper mold surface is pressed against the lower mold surface, and the driving wedge drives the driven wedge to pull the two movable upper mold cores toward the fixed upper mold core and compress and change the vertical spacing to be equal to the thickness of the part; The bottom surface of the upper mold base is formed with a concave portion, the fixed upper mold core is fixedly arranged in the concave portion, and the two movable upper mold cores are displaceably arranged in the concave portion between the limiting portion of the upper mold base and the fixed upper mold core; The elastic return member of the upper mold core is a transversely arranged spring; the side walls of the fixed upper mold core corresponding to the movable upper mold core are recessed with grooves whose openings can be matched; the two ends of the spring are respectively accommodated in the grooves of the fixed upper mold core and the movable upper mold core.

2. The thermoforming mold structure for thin parts according to claim 1, characterized in that: The limiting portion of the upper die seat is formed as a stroke limiting block, which is arranged on the bottom surface of the upper die seat around the recess, and the end of the stroke limiting block extends into the opening range of the recess.

3. The thermoforming mold structure for thin parts according to any one of claims 1 to 2, characterized in that: The driving bevel has an inclination angle α; the driving bevel is made to counteract the driven bevel, and there is a pressing stroke distance H between the upper mold surface and the lower mold surface; the pressing stroke distance H and the displacement distance S of the movable upper mold core are obtained according to the relationship H=S*cot(α).

4. The thermoforming mold structure for thin parts according to claim 3, characterized in that: The movable upper die core is movably connected to the bottom surface of the upper die seat through a slide rail mechanism.

5. The thermoforming mold structure for thin parts according to claim 4, characterized in that: The fixed upper mold core is fixedly connected to the bottom surface of the upper mold base through threads.

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