Thin-walled stainless steel tube bending die and method

Abstract

The present application discloses a thin-wall stainless steel pipe bending die, which comprises a wheel die and a clamp die. The wheel die comprises at least one first clamping groove, and the clamp die comprises at least one second clamping groove. The first clamping groove and the second clamping groove form a clamping cavity after being combined. The wheel die and / or the clamp die further comprises a sand flow channel, which is located outside the first clamping groove or / and the second clamping groove in the radial direction. The side wall of the first clamping groove or / and the second clamping groove has a plurality of sand flow-out holes penetrating in the radial direction. The sand flow channel is in communication with the first clamping groove or / and the second clamping groove. The present application discloses a thin-wall stainless steel pipe bending method. The present application has the beneficial effects that the friction coefficient is greatly increased, the clamping force is greatly improved, the product stability is greatly improved, and the production quality is more stable.

Description

Technical Field

[0001] This invention relates to a pipe fitting processing mold, and more particularly to a thin-walled stainless steel pipe bending mold and method. Background Technology

[0002] Automotive exhaust system pipes are typically made of 304 or 409L stainless steel. To allow the exhaust pipes to fit within the chassis space and avoid surrounding components, they need to be bent and deformed to create a suitable shape. Currently, bending processes are widely used in mass production due to their high production efficiency and good pipe bending quality. For example, announcement number CN212093992U describes a new type of pipe bending mold, including assembly bolts, a bending die, a clamping die assembly, and a counter. The clamping die assembly consists of a first clamping die and a second clamping die with different curvatures. The bending die is integrally assembled onto the assembly bolts. The first and second clamping dies are connected side-by-side via clamping die hanging plates. The first and second clamping dies cooperate with the bending die to bend pipes with different curvatures. The counter is fixedly installed on the side wall of the second clamping die away from the first clamping die via a protective sleeve. When the second clamping die and the bending die are closed, the counter's counting bead contacts the bending die and completes one count.

[0003] During the manufacturing process, the clamping mold and wheel mold first clamp the pipe, and rely on the friction generated by the clamping to drive the pipe to bend. Different grooves and textures are often used to increase the coefficient of friction.

[0004] However, for parts with a small bending radius, the bending moment will increase.

[0005] Bending moment ,

[0006] Wherein, D represents the outer diameter of the pipe; - The radius of curvature of the curved neutral layer; -Tensile strength of the material; - Bending section modulus; -Consider the coefficient that increases bending moment due to friction.

[0007] It can be seen that as the radius of curvature decreases, the bending moment M increases.

[0008] If the clamping force of the clamping mold and the wheel mold is insufficient, the pipe will slip, resulting in a defective final product. Currently, the market typically uses a water expansion process or a split welding process to address this type of problem, but this significantly increases costs.

[0009] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0010] The technical problem to be solved by this invention is: how to solve the problem of pipe slippage and product defects caused by insufficient clamping force due to increased bending moment for pipe fittings with small bending radii.

[0011] The present invention solves the above-mentioned technical problems through the following technical means:

[0012] A thin-walled stainless steel pipe bending die includes a wheel mold and a clamping mold. The wheel mold includes at least one first clamping groove, and the clamping mold includes at least one second clamping groove. After the first clamping groove and the second clamping groove are closed, a clamping cavity is formed. The wheel mold and / or clamping mold further includes a gravel flow channel. The gravel flow channel is located radially outside the first clamping groove and / or the second clamping groove. The sidewall of the first clamping groove and / or the second clamping groove has a plurality of radially penetrating gravel outflow holes. The gravel flow channel communicates with the first clamping groove and / or the second clamping groove.

[0013] This invention features a gravel flow channel within the wheel mold and / or clamping mold, located radially outside the clamping groove. Gravel is injected into the gravel flow channel, and the gravel flows through the gravel outlet hole to the outer surface of the stainless steel tube. Due to the effect of the gravel, the overall friction coefficient increases significantly, thereby increasing the clamping force. Even when manufacturing a small-radius bend with a large bending moment, slippage will not occur, generating a greater clamping force to address the slippage problem of small-radius bends. At the same time, due to the increase in clamping force, product stability is greatly improved, and production quality is more stable.

[0014] Preferably, the size of the gravel outflow hole is 0.5-3mm.

[0015] Preferably, the gravel outflow hole is one or a combination of round holes, square holes, elliptical holes, irregular holes, and waist-shaped holes.

[0016] Preferably, the gravel outlet holes are uniformly arranged along the axial direction of the first clamping groove and / or the second clamping groove.

[0017] Preferably, the gravel channel covers the first clamping groove and the second clamping groove.

[0018] The gravel flow channel can cover the first clamping groove and the second clamping groove as much as possible, so that the gravel outflow holes are evenly arranged in the first clamping groove and the second clamping groove, maintaining the uniformity of clamping force.

[0019] Preferably, it further includes a gravel container, which is connected to the side of the wheel mold and / or clamping mold, and the interior of the gravel container is in communication with the gravel flow channel.

[0020] Gravel containers are used to hold gravel and can provide a source of gravel for one or more gravel channels.

[0021] Preferably, it also includes a recycling box located below the wheel mold and the clamping mold.

[0022] The recycling box is used to collect gravel and prevent excess gravel from falling into the clamping mold slide rail; the recycling device can be made of materials such as metal and canvas. Alternatively, the slide rail can be sealed in another way to prevent damage.

[0023] This application also discloses a bending method using a thin-walled stainless steel bending die. The stainless steel tube is placed inside the wheel die, and the clamping die is operated to close the wheel die. Gravel is injected into the gravel flow channel. After the gravel flows out of the gravel outlet hole to the outer surface of the stainless steel tube, the wheel die and the clamping die rotate to perform bending.

[0024] Preferably, the size of the gravel is 0.01-1mm. Here, it is necessary to rationally design the ratio of the gravel outlet size to the gravel size, while also utilizing the friction of the gravel itself to prevent excessive gravel from flowing out.

[0025] Preferably, before the stainless steel tube is placed in the wheel mold, an adhesive liquid is brushed onto the surface of the first clamping groove and / or the second clamping groove.

[0026] Preferably, the flow rate and volume of the gravel are controlled according to the friction requirements.

[0027] Preferably, the gravel is injected using its own gravity, or by air pressure injection, or by vibration injection.

[0028] The bending method of this invention involves brushing a small amount of adhesive liquid (preferably a liquid that does not increase lubrication but has adhesive properties, such as bending oil) onto the surface of the clamping area before bending. During the bending process, the presence of this small amount of adhesive liquid on the surface of the clamping area causes the flowing sand and gravel to adhere evenly to the surface of the clamping area. The sand and gravel significantly increase the overall coefficient of friction, thereby increasing the clamping force. After bending, the sand and gravel are recycled. This innovative and breakthrough process provides greater design flexibility for exhaust systems, allowing for the design of pipes with smaller bending radii; it also reduces the use of water expansion and welding processes, significantly lowering the manufacturing cost of exhaust pipes.

[0029] The advantages of this invention are:

[0030] (1) The present invention provides a gravel flow channel in the wheel mold and / or clamping mold and located radially outside the clamping groove. Gravel is injected into the gravel flow channel and flows to the outer surface of the stainless steel tube through the gravel outflow hole. Due to the effect of the gravel, the overall friction coefficient will increase significantly, thereby increasing the clamping force. Even when manufacturing a small bending tube with a large bending moment, it will not slip. It generates a larger clamping force to deal with the slippage problem of small radius bending tube. At the same time, due to the increase in clamping force, the product stability is greatly improved and the production quality is more stable.

[0031] (2) The gravel flow channel can cover the first clamping groove and the second clamping groove as much as possible, so that the gravel outflow holes are evenly arranged in the first clamping groove and the second clamping groove, and the clamping force is uniform.

[0032] (3) The recycling box is used to recycle sand and gravel and prevent excess sand and gravel from falling into the clamping mold slide rail;

[0033] (4) The bending method of the present invention involves brushing a small amount of adhesive liquid onto the surface of the clamping area before bending the pipe. During the bending process, due to the presence of a small amount of adhesive liquid on the surface of the clamping area, the flowing sand can be evenly adhered to the surface of the clamping area. The sand greatly increases the overall friction coefficient, thereby increasing the clamping force. The sand is recycled after the bending is completed. The present invention provides more space for the design of the exhaust system through process innovation and breakthrough, and can design pipe fittings with smaller bending radii. It reduces the use of water expansion and welding processes, and greatly reduces the manufacturing cost of exhaust pipe fittings. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the thin-walled stainless steel tube bending mold according to an embodiment of the present invention;

[0035] Figure 2 This is an exploded view of the thin-walled stainless steel tube bending mold according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the wheel mold structure according to an embodiment of the present invention;

[0037] Figure 4 This is a front view of the wheel mold according to an embodiment of the present invention;

[0038] Figure 5 yes Figure 4 Sectional view at point AA;

[0039] Figure 6 yes Figure 3 Enlarged view of point B in the middle;

[0040] Numbering on the map:

[0041] 1. Wheel mold; 11. First clamping groove; 2. Clamping mold; 21. Second clamping groove; 3. Gravel flow channel; 4. Gravel outflow hole; 5. Gravel container; 6. Recycling box. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1:

[0044] like Figure 1 , Figure 2 As shown, the thin-walled stainless steel pipe bending mold includes a wheel mold 1 and a clamping mold 2. The wheel mold 1 includes at least one first clamping groove 11, and the clamping mold 2 includes at least one second clamping groove 21. The first clamping groove 11 and the second clamping groove 21 are closed to form a clamping cavity. In this embodiment, the wheel mold 1 includes two first clamping grooves 11, and the clamping mold 2 includes two second clamping grooves 21. The first clamping grooves 11 and the second clamping grooves 21 are positioned correspondingly. After the two are closed, two clamping cavities are formed. In this embodiment, both the first clamping groove 11 and the second clamping groove 21 are semi-circular grooves. The bending radii of the two clamping cavities are different, which can accommodate stainless steel pipes with different bending radii.

[0045] In this embodiment, the wheel mold 1 and / or clamping mold 2 further include a gravel flow channel 3, which is located radially outside the first clamping groove 11 and / or the second clamping groove 21, referring to... Figure 5 As shown, the gravel channel 3 is a semi-annular cavity with a certain thickness and an inner diameter larger than the first clamping groove 11 or the second clamping groove 21. The gravel channel 3 is located inside the wheel mold 1 and / or the clamping mold 2. In this embodiment, both the wheel mold 1 and the clamping mold 2 are provided with gravel channels. In actual use, gravel channels can also be provided separately on the wheel mold 1 or the clamping mold 2.

[0046] like Figure 2 As shown, the sidewalls of the first clamping groove 11 and the second clamping groove 21 have multiple radially penetrating gravel outflow holes 4. The gravel flow channel 3 communicates with the first clamping groove 11 and the second clamping groove 21 through the gravel outflow holes 4. The size of the gravel outflow holes 4 is 0.5-3mm. The gravel outflow holes 4 are one or a combination of round holes, square holes, elliptical holes, irregular holes, and oblong holes. Here, irregular holes refer to irregular round holes, square holes, etc. Figure 6 As shown in the figure, this embodiment uses the gravel outflow hole 4 as a circular hole for demonstration.

[0047] The gravel outlet holes 4 are uniformly arranged along the axial direction of the first clamping groove 11 and the second clamping groove 21. This uniform arrangement can be a matrix layout. The gravel flow channel 3 located inside the wheel mold 1 covers the first clamping groove 11, and the gravel flow channel 3 located inside the clamping mold 2 covers the second clamping groove 21. "Covering" here means that the length of the gravel flow channel 3 is at least equal to the length of the area containing the gravel outlet holes 4, and the range of the inner arc surface of the gravel flow channel 3 is also at least equal to the range of the arc surface containing the gravel outlet holes 4. That is, each gravel outlet hole 4 can communicate with the gravel flow channel 3, and each gravel outlet hole 4 can allow gravel to flow out. The gravel flow channel 3 can cover the first clamping groove 11 and the second clamping groove 21 as much as possible, so that the gravel outlet holes 4 are evenly arranged in the first clamping groove 11 and the second clamping groove 21, maintaining the uniformity of the clamping force.

[0048] In this embodiment, the gravel channel 3 is located inside the wheel mold 1 and the clamping mold 2, and its two ends in the axial direction do not penetrate through each other. One end of the gravel channel 3 has an inlet that communicates with the outside of the wheel mold 1 and the clamping mold 2 for injecting gravel. Of course, gravel can also be injected from the top of the gravel channel 3. The number of inlets is not limited. If the gravel channel 3 is too curved or long, gravel can be injected through two inlets.

[0049] like Figure 2 As shown, the thin-walled stainless steel pipe bending mold also includes a gravel container 5, wherein the gravel container 5' is connected to the front side of the wheel mold 1, and the gravel container 5" is connected to the front side of the clamping mold 2. Figure 5 As shown, the interior of the gravel container 5 is connected to the gravel flow channel 3. The gravel container 5 is used to hold gravel and can provide a gravel source for one or more gravel flow channels 3, such as... Figure 5 As shown, the arrows indicate the direction of gravel injection. The gravel container 5' of the wheel mold 1 can simultaneously supply gravel to both gravel channels 3. Furthermore, as can be seen from the figure, the inlets of the gravel channels 3 are all located at relatively high positions, facilitating the gravel's descent under its own weight.

[0050] like Figure 2 As shown, the thin-walled stainless steel pipe bending mold also includes a recycling box 6, which is located below the wheel mold 1 and the clamping mold 2. The recycling box 6 is a rectangular box with an open top surface. The recycling box 6 is used to collect sand and gravel, preventing excess sand and gravel from falling into the slide rail of the clamping mold 2. The recycling box 6 can also be other shapes, such as circular or elliptical, and can be made of materials such as metal or canvas, but not limited to. Alternatively, other methods can be used to close or cover the slide rail to prevent damage.

[0051] Gravel left on the mold surface does not affect the use of the mold, and no cleaning is required after use.

[0052] In this embodiment, a gravel flow channel 3 is provided within the wheel mold 1 and the clamping mold 2, and located radially outside the clamping groove. Gravel is injected into the gravel flow channel 3, and the gravel flows to the outer surface of the stainless steel tube through the gravel outflow hole 4. Due to the effect of the gravel, the overall friction coefficient will increase significantly, thereby increasing the clamping force. Even when manufacturing a small-radius bend, the large bending moment will not cause slippage, generating a larger clamping force to cope with the slippage problem of small-radius bends. At the same time, due to the increase in clamping force, the product stability is greatly improved, and the production quality is more stable.

[0053] Example 2:

[0054] This embodiment discloses a bending method using the thin-walled stainless steel bending die from Embodiment 1, comprising the following steps:

[0055] First, apply an adhesive liquid to the surfaces of the first clamping groove 11 and the second clamping groove 21. Apply a small amount of adhesive liquid (preferably a liquid that does not increase lubrication but has adhesive properties, such as pipe bending oil) to the surface of the clamping area. During the pipe bending process, since there is a small amount of adhesive liquid on the surface of the clamping area, the flowing sand can be evenly adhered to the surface of the clamping area.

[0056] Then, place the stainless steel pipe inside the wheel mold 1, and operate the clamping mold 2 to close the wheel mold 1. Gravel is injected into the gravel flow channel 3 from the gravel container 5. After the gravel flows out from the gravel outlet hole 4 to the outer surface of the stainless steel pipe, the wheel mold 1 and the clamping mold 2 rotate to bend.

[0057] In this embodiment, the size of the gravel is 0.01-1 mm, and the size of the gravel outlet hole 4 is 0.5-3 mm. The ratio of the size of the gravel outlet hole 4 to the size of the gravel needs to be designed appropriately. If greater friction is required, the radius of the gravel outlet hole 4 can be increased, allowing more gravel to flow out and thus increasing friction. If less friction is required, the radius of the gravel outlet hole 4 can be decreased, reducing the amount of gravel flowing out and thus decreasing friction. However, the gravel outlet hole 4 should not be set too large while the gravel size is too small, as this would result in excessive gravel flowing out and failing to retain it within the clamping cavity, thus negating the effect of increasing friction.

[0058] The flow rate of the gravel can also be controlled according to the required friction. For example, when the bending radius is small and a larger friction is needed, the flow rate of the gravel can be increased; if the bending radius is large and a smaller friction is needed, the flow rate of the gravel can be reduced. The gravel is injected using its own gravity, or, if the gravel channel 3 is too long or too curved, it can be injected using air pressure injection or vibration injection. The flow rate can be controlled by adjusting the air pressure injection pressure, vibration frequency, or gravel inlet size.

[0059] This embodiment uses gravel, which significantly increases the overall coefficient of friction, thereby enhancing the clamping force. The gravel is then recycled after bending. Through technological innovation and breakthroughs, greater design flexibility is provided for the exhaust system, allowing for the design of pipes with smaller bending radii; the use of water expansion and welding processes is reduced, significantly lowering the manufacturing cost of exhaust pipes.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bending die for thin-walled stainless steel pipes, comprising a wheel die and a clamping die, wherein the wheel die includes at least one first clamping groove, and the clamping die includes at least one second clamping groove, wherein the first clamping groove and the second clamping groove, when closed, form a clamping cavity, characterized in that... The wheel mold and / or clamping mold also includes a gravel flow channel, which is located radially outside the first clamping groove and / or the second clamping groove. The sidewalls of the first clamping groove and / or the second clamping groove have multiple radially penetrating gravel outflow holes. The gravel flow channel is connected to the first clamping groove and / or the second clamping groove. Before the stainless steel tube is placed on the wheel mold, an adhesive liquid is brushed onto the surface of the first clamping groove and / or the second clamping groove.

2. The thin-walled stainless steel pipe bending die according to claim 1, characterized in that, The size of the gravel outflow hole is 0.5-3mm.

3. The thin-walled stainless steel pipe bending die according to claim 1, characterized in that, The gravel outflow hole is one or a combination of round holes, square holes, elliptical holes, irregular holes, and waist-shaped holes.

4. The thin-walled stainless steel pipe bending die according to claim 1, characterized in that, The gravel outflow holes are uniformly arranged along the axial direction of the first clamping groove and / or the second clamping groove.

5. The thin-walled stainless steel pipe bending die according to claim 1, characterized in that, It also includes a gravel container, which is connected to the side of the wheel mold and / or clamping mold, and the interior of the gravel container is in communication with the gravel flow channel.

6. The thin-walled stainless steel pipe bending die according to claim 1, characterized in that, It also includes a recycling box located below the wheel mold and the clamping mold.

7. A bending method using the thin-walled stainless steel tube bending die according to any one of claims 1-6, characterized in that, The stainless steel pipe is placed inside the wheel mold, and the clamping mold is operated to close the wheel mold. Gravel is injected into the gravel flow channel. After the gravel flows out of the gravel outlet hole to the outer surface of the stainless steel pipe, the wheel mold and clamping mold rotate to bend.

8. The bending method according to claim 7, characterized in that, The size of the gravel is 0.01-1mm.

9. The bending method according to claim 7, characterized in that, The gravel is injected using its own gravity, or by air pressure injection, or by vibration injection.

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