High-aspect-ratio foil groove array feature forming die and method

Abstract

The invention discloses a high aspect ratio foil groove array feature forming die and method, a metal foil is rolled through teeth A and teeth B on a first compression roller and a second compression roller, the teeth A on the first compression roller are consistent with the teeth of a female die, and within the same time, only one set of teeth A and teeth B conduct tooth profile feature forming; the rolled semi-finished product is flatly laid on the female die, the convex face of the rolled semi-finished product is arranged on the convex edge of the female die in a sleeving mode, the concave face falls into the groove of the female die, and self-positioning is achieved under the action of resilience force; and finally, stamping to obtain the structural member with the high aspect ratio foil groove array characteristic. The first pressing roller is arranged according to the female die pattern of the stamping die, a rolled semi-finished product can completely cover the female die, and accurate positioning is achieved; during rolling, the tooth-shaped characteristics are formed in sequence, and the foil is bent and deformed; positioning is achieved through the resilience force of the rolled semi-finished product, positioning holes and a subsequent positioning hole cutting process are not needed, the forming process is simplified, and waste of raw materials is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of foil groove forming, and in particular to a high aspect ratio foil groove array feature forming die and method. Background Art

[0002] The metal foil groove structure with high aspect ratio flow channels has the typical feature of a single flow channel size at the sub-millimeter and millimeter levels. The overall flow channel is formed by combining a large-area dense array, which can achieve high flux, high specific surface area, high specific strength and other characteristics. It is widely used in high-efficiency heat exchangers, aircraft rudder wing honeycomb structures, fuel cells, and microreactors.

[0003] At present, the one-time stamping process is mainly used to prepare the microchannel features on the surface of metal foil. However, the stamping process is short and the strain rate is high, so it is difficult to form a channel with a depth greater than 0.45mm (aspect ratio ≥ 40%) on the metal foil. The limiting factor for the mass production of metal foils with high aspect ratio microchannel features (mainly 0.1mm stainless steel) is that the local thinning rate of the foil is too large, and it is easy to break during the forming process (the most common location is the fillet position of the channel).

[0004] Patent CN201611091387.1 proposes to adopt a roll-stamping composite forming process, which combines roll-bending forming and stamping thinning and drawing forming to achieve the preparation of high aspect ratio metal sheet microstructures. The roll-forming roller die is used to roll-form the metal sheet to obtain an initial micro-feature sheet with an initial microstructure; the initial micro-feature sheet is subjected to leveling, stamping positioning holes, and stamping trimming processes to finally obtain a high aspect ratio metal sheet microstructure in the target form. The stamping and trimming combination includes a stamping die and a trimming die, which are used to stamp and trim the initial micro-feature sheet. This scheme is feasible under the most ideal conditions, but it is very unfeasible in the actual forming process and has several defects:

[0005] 1. The patent includes a pair of forming rollers for roll-forming metal foil. The diameter and number of teeth of these two rollers are consistent, and the transmission overlap is greater than 1. That is, when each tooth feature on the metal sheet is formed, other tooth features are also formed. The material elongation rate increases with the increase of the depth-to-width ratio, thereby causing the risk of fracture during subsequent stamping.

[0006] 2. After each tooth-shaped feature on the metal sheet is initially formed, because it is a combination of bending and drawing, it will inevitably rebound in the up and down and horizontal directions. Its up and down height and horizontal length are different from the ideal state, and the depth will not meet the standard and the length in the horizontal direction will exceed the standard. There will be a size difference with the subsequent stamping die, and it is easy to squeeze the material and break during stamping.

[0007] 3. This patent requires punching of positioning holes before roll forming, and uses the positioning holes to achieve precise positioning of the initial fine feature thin plate to avoid material extrusion. The premise of precise positioning using positioning holes is that the semi-finished product is completely flat and the fixed surface is a plane. According to the array tooth-shaped microstructure of the initial fine feature thin plate, the flatness is poor and it is difficult to meet the positioning requirements of the positioning holes. Relying on positioning holes for positioning, the part where the semi-finished product contacts the mold is a point and line feature, and the positioning reliability is far less than that of surface positioning. Relying on positioning holes for positioning, due to the existence of positioning deviations, when stamping high-quality products, the gap between the upper and lower concave and convex dies of the mold is small, and the draft angle is small, it is very easy to cause the product to break during stamping.

[0008] 4. Positioning holes will increase production processes and waste materials. Summary of the invention

[0009] In order to solve the above problems, the present invention provides a high aspect ratio foil groove array feature forming die and method, which greatly reduces the maximum thinning rate of foil forming and realizes stamping batch production of metal foil with high aspect ratio groove array features.

[0010] To this end, the technical solution of the present invention is: a high aspect ratio foil groove array feature forming mold, including a rolling mold and a stamping mold, the stamping mold includes a matching punch and a die; the rolling mold includes a first pressing roller and a second pressing roller, a first tooth structure is arranged on the outer side of the first pressing roller, the size and spacing of the teeth A on the first tooth structure are consistent with the teeth on the die, that is, the first tooth structure is consistent with the tooth structure of the die after flattening; a second tooth structure is arranged on the outer side of the second pressing roller, and the width of the teeth B on the second tooth structure is smaller than the width of the teeth A on the first tooth structure.

[0011] On the basis of the above scheme and as a preferred scheme of the above scheme: during the rolling process, the teeth A on the first pressing roller and the teeth B on the second pressing roller are rolled one by one, and at the same time, there is only one set of teeth A and teeth B in the process of forming tooth shape features.

[0012] On the basis of the above scheme and as a preferred scheme of the above scheme: the tooth B on the second toothed structure is a special-shaped tooth, and the tooth shape of the tooth B meshes with the tooth A without interfering.

[0013] Another technical solution of the present invention is: a method for forming a high aspect ratio foil groove array feature, comprising the following steps:

[0014] 1) The metal foil is rolled by a first pressing roller and a second pressing roller, and at the same time, only one set of teeth A and teeth B on the first pressing roller and the second pressing roller act on the metal foil, that is, at the same time, only one tooth-shaped feature is formed, and when the metal foil is bent, the free end can add material to the bending position to obtain a rolled semi-finished product; the width of the convex surface on the rolled semi-finished product is greater than the width of the concave surface, and the two sides of the convex surface are connected to the concave surface by an inclined surface;

[0015] 2) Lay the rolled semi-finished product flat on the die, with the convex surface of the rolled semi-finished product sleeved on the convex ridge of the die, and the concave surface falling into the groove of the die; under the action of the rebound force, the inclined surfaces on both sides of the concave surface tend to expand horizontally, so that it clamps the convex ridge of the die to achieve self-positioning;

[0016] 3) The stamping die is started, and the punch presses and rolls the semi-finished product downward to obtain a structural part having a high aspect ratio foil groove array feature.

[0017] On the basis of the above scheme and as a preferred scheme of the above scheme: during the rolling process, the first pressing roller and the second pressing roller only bend the metal foil as required, and the bending produces alternating convex surfaces, inclined surfaces, concave surfaces, and inclined surfaces, and the inclined surfaces contain the deformation allowance for subsequent stamping.

[0018] The present invention sets the first tooth structure of the first roller according to the concave die style of the stamping die, and the second tooth structure of the second roller is set to a special-shaped structure, and the larger the difference in the number of teeth between the second roller and the first roller, the better, as long as the intermediate shaft of the second roller does not undergo large bending deformation. The larger the difference in the number of teeth of the two rollers, the smaller their overlap, and combined with the special-shaped wheel, it is ensured that during the rolling process, only one tooth feature of the corresponding teeth A and B on the second roller and the first roller is formed, and the bending of the metal foil is achieved by sequentially forming the tooth shape, rather than bending and drawing deformation, and the sequential forming makes the metal foil itself not thin during the rolling process, thereby reserving material stretching space for subsequent stamping.

[0019] Because the widths of the teeth on the first pressing roller and the second pressing roller are different, the convex surface and the concave surface will be connected by an inclined surface when the metal foil is bent. Compared with the final vertical surface, this inclined surface stores excess material, and relatively directly punches once. The present invention will not cause the problem of rupture due to excessive material stretching rate during the subsequent stamping process.

[0020] The key to the rolling-stamping cooperation of the present invention is positioning. As long as the overall material stretching is within the stretching range of the material itself, successful stamping can be achieved with precise positioning and accurate molds. Since the material is bent and folded during the rolling process, there is rebound after the rolling is completed, but each tooth-shaped feature needs to be precisely positioned, so the positioning hole positioning method is not suitable for the rolling-stamping composite method. The stamping of the present invention adopts a self-positioning method, which uses the rebound force to self-fix on the die, because the first pressing roller is the unfolded form of the die, and when the rolled semi-finished product is fixed, the rolled semi-finished product is easily fixed on the die, so that it is accurately positioned on each raised edge of the die. The advantage of self-positioning is that the positioning deviation will not be transmitted to the adjacent features, and its positioning method greatly improves the reliability of surface positioning and the positioning accuracy.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Combine traditional roll forming technology with stamping process and apply it to the processing of groove array features on the surface of foil, so as to realize mass production of grooves with high aspect ratio by stamping; the roll forming die can form the flow channel of metal foil at room temperature, and only one feature is formed at the same time, so as to bend and deform the foil.

[0023] 2. The first pressing roller is set according to the concave die style of the stamping die, and the rolled semi-finished product can be completely covered on the concave die to achieve precise positioning; the overlap of the teeth on the first pressing roller and the second pressing roller is 1, that is, only one tooth shape feature of the corresponding two teeth is formed during the rolling process, so as to achieve the bending of the metal foil instead of bending, thereby ensuring that the rolled semi-finished product can be laid flat on the stamping die and the accuracy of stamping is guaranteed.

[0024] 3. The self-resilience of the rolled semi-finished product is used to achieve positioning, without the need to set positioning holes and subsequent positioning hole cutting processes, which simplifies the forming process and reduces the waste of raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a forming flow chart of the present invention;

[0026] Figure 2 Schematic diagram of the rolling process of the present invention;

[0027] Figure 3 for Figure 2 A partial enlarged view of

[0028] Figure 4 This is a schematic structural diagram of the roll-pressed semi-finished product of the present invention;

[0029] Figure 5 It is a schematic diagram of the stamping process of the present invention;

[0030] Figure 6 for Figure 5A partial enlarged view of

[0031] Figure 7 It is a structural schematic diagram of the finished product of the present invention.

[0032] Marked in the figure are: first pressing roller 1, first tooth structure 11, tooth A12, second pressing roller 2, second tooth structure 21, tooth B22, punch 3, die 4, metal foil 5, rolled semi-finished product 6, convex surface 61, concave surface 62, inclined surface 63, structural part 7. DETAILED DESCRIPTION

[0033] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present invention.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. Therefore, the definition of "first" and "second" features can explicitly or implicitly include one or more of the features. In the description of the present invention, "several" and "a number" mean two or more, unless otherwise clearly and specifically defined.

[0035] See the attached drawings. The high aspect ratio foil groove array feature forming die described in this embodiment includes a rolling die and a stamping die, and the stamping die includes a matching convex die 3 and a concave die 4; the rolling die includes a first pressing roller 1 and a second pressing roller 2, and a first tooth structure 11 is arranged on the outer side of the first pressing roller 1. The size and spacing of the teeth A12 on the first tooth structure 11 are consistent with the teeth on the concave die 4, that is, the first tooth structure 11 is consistent with the tooth structure of the concave die 4 after being flattened. The first pressing roller is set using the concave die style of the stamping die, and the rolled semi-finished product can be completely covered on the concave die to achieve precise positioning of the stamping.

[0036] The second roller 2 is provided with a second tooth structure 21 on the outer side, the width of the tooth B22 on the second tooth structure 21 is smaller than the width of the tooth A12 on the first tooth structure 11, the tooth B22 on the second tooth structure 21 is a special-shaped tooth, and the tooth B is a tooth shape designed based on the meshing and non-interference of the tooth A. During the rolling process, the tooth A12 on the first roller 1 and the tooth B22 on the second roller 2 are rolled one by one, and at the same time, only one set of teeth A12 and teeth B22 are used to form the tooth shape features, that is, only one set of teeth A12 and teeth B22 are used to process the tooth shape on the metal foil, so that the metal foil material itself does not become thinner during the rolling process, thereby reserving material stretching space for subsequent stamping.

[0037] The difference in the number of teeth between the second roller 2 and the first roller 1 is large, and the overlap is 1. Combined with the special-shaped structure, it can be ensured that during the rolling process, only one tooth shape feature of the tooth A12 on the first roller 1 and the tooth B22 on the second roller 2 is formed, and the bending of the metal foil is achieved by sequential forming rather than bending and drawing deformation.

[0038] The process steps are as follows:

[0039] 1) The metal foil 5 is rolled by the first pressing roller 1 and the second pressing roller 2. At the same time, only one set of teeth A12 and teeth B22 act on the metal foil 5. Only one tooth-shaped feature is being formed on the metal foil 5, that is, the tooth-shaped features on the metal foil 5 are tooth-shaped in sequence. The metal foil is bent by forming in sequence. When bending, the feeding side of the metal foil 5 is a free end. During the forming process, the free end can be supplemented with material to avoid excessive stretching of the material, so as to obtain a rolled semi-finished product 6. The width of the convex surface 61 on the rolled semi-finished product 6 is greater than the width of the concave surface 62. The two sides of the convex surface 61 are connected to the concave surface 62 by inclined surfaces 63. The bending produces alternating convex surfaces 61, inclined surfaces 63, concave surfaces 62, and inclined surfaces 63. The inclined surface 63 includes the deformation margin of subsequent stamping. In the subsequent stamping process, the material will not be stretched too much to cause rupture, such as Figure 1 shown.

[0040] 2) Spread the rolled semi-finished product 6 on the die 4, with the convex surface 61 of the rolled semi-finished product 6 sleeved on the convex ridge of the die 4, and the concave surface 62 falling into the groove of the die 4; under the action of the rebound force, the inclined surfaces 63 on both sides of the concave surface 62 will tend to expand horizontally, so that it clamps the convex ridge of the die 4 to achieve self-positioning; the advantage of self-positioning is that it will not transmit the positioning deviation to the adjacent features, and its positioning method greatly improves the surface positioning reliability and positioning accuracy. Because the first tooth structure 11 of the first pressure roller 1 is the unfolded form of the die 4, when fixing the rolled semi-finished product 6, it is easy to be fixed on the die 4, and each convex ridge of the die 4 is a positioning reference. Figure 4 , Figure 5As shown, as long as the overall material stretching is within the material's own stretching range, successful stamping can be achieved with precise positioning and accurate molds. The positioning holes can be removed and the deformation of the foil itself can be used to achieve the self-positioning function.

[0041] 3) The stamping die is started, and the punch 3 cooperates with the die 4. The punch 3 presses and rolls the semi-finished product 6 downward to obtain a structural part 7 having a high aspect ratio foil groove array feature.

[0042] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A high aspect ratio foil groove array feature forming die, comprising a rolling die and a stamping die, wherein the stamping die comprises a matching convex die and a concave die; characterized in that: The rolling mold includes a first pressing roller and a second pressing roller. A first tooth structure is arranged on the outer side of the first pressing roller. The size and spacing of the teeth A on the first tooth structure are consistent with the teeth on the die, that is, the first tooth structure is consistent with the tooth structure of the die after being flattened; a second tooth structure is arranged on the outer side of the second pressing roller. The width of the teeth B on the second tooth structure is smaller than the width of the teeth A on the first tooth structure.

2. A high aspect ratio foil groove array feature forming die as claimed in claim 1, characterized in that: During the rolling process, the teeth A on the first roller and the teeth B on the second roller are rolled one by one, and at the same time, only one set of teeth A and teeth B are forming the tooth shape features.

3. A high aspect ratio foil groove array feature forming die as claimed in claim 1, characterized in that: The tooth B on the second toothed structure is a special-shaped tooth, and the tooth shape of the tooth B meshes with the tooth A without interfering.

4. A method for forming a high aspect ratio foil groove array feature, characterized in that: Using the forming mold according to any one of claims 1 to 3 comprises the following steps: 1) The metal foil is rolled by a first pressing roller and a second pressing roller, and at the same time, only one set of teeth A and teeth B on the first pressing roller and the second pressing roller act on the metal foil, that is, at the same time, only one tooth-shaped feature is formed, and when the metal foil is bent, the free end can add material to the bending position to obtain a rolled semi-finished product; the width of the convex surface on the rolled semi-finished product is greater than the width of the concave surface, and the two sides of the convex surface are connected to the concave surface by an inclined surface; 2) Lay the rolled semi-finished product flat on the die, with the convex surface of the rolled semi-finished product sleeved on the convex ridge of the die, and the concave surface falling into the groove of the die; under the action of the rebound force, the inclined surfaces on both sides of the concave surface tend to expand horizontally, so that it clamps the convex ridge of the die to achieve self-positioning; 3) The stamping die is started, and the punch presses and rolls the semi-finished product downward to obtain a structural part having a high aspect ratio foil groove array feature.

5. A method for forming a high aspect ratio foil groove array feature according to claim 4, characterized in that: During the rolling process, the first pressing roller and the second pressing roller only bend the metal foil as required, and the bending produces alternating convex surfaces, inclined surfaces, concave surfaces, and inclined surfaces, and the inclined surfaces contain the deformation margin for subsequent stamping.

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