A mold core structure with uniform and rapid cooling function and an equal-wall necking tube mold

Abstract

The present invention discloses a die core structure and an equal-wall pipe shrinking die with a uniform and rapid cooling function, including a pipe shrinking die core and a die core rod. The pipe shrinking die core is arranged on the outer pipe wall of the pipe blank, and the die core rod is arranged on the inner pipe wall of the pipe blank. One end of the die core rod is a forming end, and the other end is a fixed end. The forming end of the die core rod is sequentially divided into a first, a second, and a third connection section from the outside to the inside. The first connection section is provided with a plurality of coolant diversion channels, the second connection section is recessed with a cooling groove, the bottom of the cooling groove is provided with a coolant output hole, and the third connection section is provided with a plurality of coolant diversion channels; a hollow coolant inlet chamber is arranged inside the die core rod, and the coolant inlet chamber is communicated with the coolant output hole and / or the coolant diversion channels. In this case, the forming position where the pipe blank material is most likely to deform is strengthened for cooling. By improving the layout structure of the cooling channels, the lubricating and cooling uniformity of the forming end of the core rod and the core head is effectively improved, and the service life of the die core structure is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of metal workpiece processing, and particularly to a die core structure with uniform and rapid cooling functions and an equal-wall pipe shrinking die. Background Art

[0002] Equal-wall diameter reduction is a metal pipe processing technology aimed at changing the diameter of the pipe while keeping its wall thickness uniform. This technology has wide applications in industries such as aerospace, automotive manufacturing, petrochemical, etc. The key to achieving equal-wall diameter reduction lies in precisely controlling the material flow and deformation process to ensure the uniformity of the wall thickness distribution throughout the forming area. During the processing, the equal-wall pipe shrinking die plays a key forming role.

[0003] Existing equal-wall pipe shrinking dies, as shown in the patent number CN115090774A, include a unary unit and a binary unit, which are respectively slidably installed on the pipe shrinking equipment. Both have the functions of synchronous sliding process and independent sliding process. Among them, the unary unit is provided with a pipe shrinking die core for reducing the diameter of the pipe, and the binary unit is provided with a die core rod for keeping the wall thickness of the reduced-diameter pipe uniform. The pipe shrinking die core and the die core realize the equal-wall diameter reduction of the metal pipe under the sliding cooperation of the unary unit and the binary unit to meet the usage requirements of metal tubular hollow products in different industries.

[0004] However, the defects of the existing equal-wall pipe shrinking dies in the cooling function are mainly reflected in the following aspects:

[0005] (1) The cooling mechanism adopted in the wall thickness shrinking pipe die shown in the above patent mainly sets a water inlet pipe and a water spray nozzle in the binary unit. The water spray nozzle sprays and cools the outer wall of the die core rod. Its cooling effect is not ideal. Especially for the forming end of the die core rod inserted into the pipe shrinking die core, the cooling effect is very weak, the cooling is uneven, and the cooling efficiency is low, resulting in defects such as shrinkage holes, warping, and increased internal stress in the products, reducing the production efficiency and increasing the cost.

[0006] (2) Difficult maintenance of the cooling system: The water spray nozzle of the above patent is set in the cavity of the binary unit. When replacing the worn part, the water spray nozzle, the entire binary unit needs to be disassembled. The cooling system design is relatively complex, resulting in difficulties in maintenance and cleaning.

[0007] (3) Unreasonable cooling path design: The cooling position of the cooling mechanism of the above patent is in the binary unit, and the cooling path is too short and the layout is unreasonable, resulting in the coolant being unable to effectively reach the key part of the die (the forming end of the die core rod), affecting the cooling effect.

[0008] (4) Influence of the cooling system on the die life: Improper cooling may cause excessive local temperature of the die, thus accelerating the wear and deformation of the die material and shortening the service life of the die.

[0009] (5) The die mandrel of the above patent is a single-piece pull rod die core without a guiding end, which is prone to pulling deviation and damage, and has a high use cost; to disassemble the die mandrel, the whole die needs to be disassembled before it can be taken out. When replacing the die mandrel, it is time-consuming and laborious; without a lubrication system, the resistance increases and the mandrel is extremely easy to break; the mandrel wears rapidly due to high temperature and friction. Summary of the Invention

[0010] In order to overcome the deficiencies of the prior art, one of the purposes of the present invention is to provide a die core structure with uniform and rapid cooling functions. This application strengthens the cooling of the forming end of the mandrel, the die core and the forming position of the tube blank material of the tube blank where deformation is most likely to occur. By improving the layout structure of the cooling channels, on the premise of not affecting the realization of the equal-wall tube shrinking process of the die, a circulating liquid path is introduced at the forming end of the die mandrel, extending the circulation path of the overall cooling channels, deeply cooling the inner wall of the middle part of the tube blank and the inner walls at both ends of the tube blank, effectively improving the uniformity of cooling, ensuring that the cooling speed of the material in the die is consistent. The functions of this uniform lubrication and cooling effectively avoid high temperature and rapid wear at each connection section of the forming end of the die mandrel, the die core and other positions, effectively restricting defects such as shrinkage holes, warping, and increased internal stress in the product, and improving the finished product quality.

[0011] Another purpose of the present invention is to provide an equal-wall tube shrinking die with uniform and rapid cooling functions.

[0012] One of the purposes of the present invention is realized by the following technical solution: A die core structure with uniform and rapid cooling functions, including a tube shrinking die core for reducing the diameter of the tube blank and a die mandrel for keeping the wall thickness of the reduced-diameter tube blank uniform. The tube shrinking die core is arranged on the outer tube wall of the tube blank, and the die mandrel is arranged on the inner tube wall of the tube blank.

[0013] One end of the die mandrel is the forming end, and the other end is the fixed end. The forming end of the die mandrel is sequentially divided into a first connection section, a second connection section, and a third connection section from the outside to the inside. The above structure forms a mandrel forming end assembly.

[0014] Among them, a plurality of coolant diversion channels are provided in the first connection section close to the outside, a cooling groove is recessed in the second connection section in the middle position, a coolant output hole is provided at the bottom of the cooling groove, and a plurality of coolant diversion channels are provided in the third connection section close to the inside; a hollow coolant inlet chamber is provided inside the die mandrel, and the coolant inlet chamber is communicated with the coolant output hole and / or the coolant diversion channels. The above structure forms the cooling and lubrication structure of the die mandrel.

[0015] Further, the die mandrel includes a mandrel body and a forming head detachably connected to the forming end of the mandrel body. The forming head includes the first connecting section, the second connecting section, and the third connecting section. The first connecting section, the second connecting section, and the third connecting section are of a split structure and are respectively detachably sleeved on the mandrel body.

[0016] Further, the outer peripheral diameter of the first connecting section is equal to the outer peripheral diameter of the third connecting section, and the outer peripheral diameter of the second connecting section is smaller than the outer peripheral diameter of the first connecting section; the maximum outer wall surfaces of the first connecting section and the third connecting section are guiding and deviation-correcting surfaces for keeping the wall thickness of the reduced-diameter pipe uniform.

[0017] Further, the lubricating and cooling coolant inlet chamber of the die mandrel structure includes a horizontal inlet chamber horizontally arranged inside the die mandrel, a radial inlet chamber connected to the outlet end of the horizontal inlet chamber, and an annular groove arranged on the outer surface of the die mandrel; the horizontal inlet chamber, the radial inlet chamber, and the annular groove are sequentially communicated, and the annular groove is communicated with the coolant output hole or / and the coolant diversion channel.

[0018] Further, a liquid outlet channel is also opened at the bottom of the cooling groove of the second connecting section. The liquid outlet channel includes radially distributed liquid outlet holes and an annular groove arranged on the side wall. The liquid outlet holes are communicated with the annular groove, and the annular groove is communicated with the coolant diversion channel of the first connecting section.

[0019] Further, the first connecting section is in a conical shape, and the diameter of the first connecting section gradually narrows from the inside to the outside. Each of the coolant diversion channels located in the first connecting section is evenly distributed inside the first connecting section, and the coolant diversion channels are radially and gradually inclined and narrowed toward the outside.

[0020] Further, a connecting piece is also arranged on the outside of the first connecting section. An annular groove and a radial groove connected to the annular groove are arranged on the side wall of the connecting piece; the output ends of the respective coolant diversion channels on the first connecting section are distributed on the annular groove, and the coolant flowing out of the radial groove is used for cooling and lubricating the unit components at the end and the inner wall of the pipe blank.

[0021] Further, a spiral channel is arranged on the outer wall of the pipe shrinking die core. Liquid inlet holes and liquid outlet holes are arranged at both ends of the spiral channel. The liquid inlet holes are communicated with a cooling source, and the coolant flowing out of the liquid outlet holes is used for lubricating and cooling the die core and the outer wall of the pipe blank to reduce friction and lower the temperature.

[0022] Further, the inner cavity of the tube shrinking die core includes a tapered section and a straight cylinder section connected to the narrow end of the tapered section. The minimum inner diameter of the tapered section is greater than the outer diameter of the tube blank, and the inner diameter of the straight cylinder section is equivalent to the outer diameter of the tube blank. In the open die state, the forming end of the tube shrinking die core is located in the straight cylinder section of the tube shrinking die core, and the distance between the outer surface of the forming end of the die core rod and the inner wall of the straight cylinder section of the tube shrinking die core is the same as the wall thickness of the tube blank after tube shrinking.

[0023] The second object of the present invention is achieved by the following technical solution: An equal-wall tube shrinking die includes a binary unit and a binary unit. The binary unit and the binary unit are respectively slidably mounted on the tube shrinking equipment, and the binary unit and the binary unit have a synchronous sliding process and their respective independent sliding processes. The equal-wall tube shrinking die further includes the die core structure with uniform and rapid cooling function as described above. The die core rod is mounted on the binary unit for reducing the diameter of the tube blank, and the tube shrinking die core is mounted on the binary unit for keeping the wall thickness of the tube blank after diameter reduction uniform. The tube shrinking die core and the die core rod achieve equal-wall diameter reduction of the metal tube under the sliding cooperation of the binary unit and the binary unit.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) In this application, enhanced cooling is carried out for the forming positions where the materials of the forming end of the die core rod, the die core, and the tube blank are most vulnerable to extrusion and local high-temperature deformation. By improving the layout structure of the cooling channels, without affecting the realization of the equal-wall tube shrinking process of the die, a circulating liquid path is introduced at the forming end of the die core rod. At the same time, the original single-piece forming head of the die core rod is improved into multiple unit components, adding parts such as circulating flow and jet flow diversion, extending the circulation path of the overall cooling channel, and deeply cooling and lubricating the forming end of the rod core, the die core, the inner walls of the middle part, both ends of the tube blank, and the outer walls, effectively improving the uniformity of cooling, ensuring that the cooling speed of the material in the die is consistent. This uniform cooling effectively avoids defects such as shrinkage holes, warping, and increased internal stress in the product, and improves the finished product quality.

[0026] (2) In addition, the cooling of this die core structure is uniform, shortening the cooling time, thereby improving the lubricating and cooling efficiency and reducing the production cost.

[0027] (3) This die core structure extends the service life of the die, avoiding defects such as accelerated wear and deformation of the die material and shortened service life of the die caused by excessive local friction and high temperature of the die.

[0028] (4) In this application, the die mandrel is designed as multiple connecting components, and each connecting component is detachably installed at the forming end of the die mandrel. The structure at the forming end of the die mandrel is improved to add lubrication and cooling functions, effectively suppressing the problem of increased costs caused by high temperature and rapid wear. It can also achieve the connection and communication between cooling channels, and facilitate rapid repair, replacement, and maintenance in the later stage.

[0029] (5) This guiding and deviation-correcting surface is the main pressure-bearing surface during the equal-wall tube shrinking process. In this structure, the coolant groove is designed in the middle position. During the equal-wall tube shrinking process, the tube blank is lubricated and cooled while being pressed, improving the lubrication and cooling effect, reducing the friction with the forming head assembly, extending the service life of the assembly, and effectively avoiding defects such as shrinkage holes, warping, and increased internal stress in the product, thereby improving the finished product quality.

[0030] (6) Preferably, the outer first connecting section of this application is designed as a cone, and the position where its cone narrows is close to the middle of the tube blank, so that the coolant diversion channels inside the first connecting section can gradually narrow inward along the coolant flow direction, which can avoid the reverse flow of the cooling channels, improve the flow smoothness of the cooling channels, and enhance the cooling effect.

[0031] (7) This application adds a connecting piece. The connecting piece has two functions. One is to fix the installation positions of the first connecting section, the second connecting section, and the third connecting section. The inner ring of the connecting piece is provided with threads and is fixedly connected to the end of the mandrel body by threads to achieve rapid assembly. The other is to set radial grooves on the connecting piece, which can effectively spray the coolant from multiple angles to the contact part between the forming head assembly and the inner wall of the tube blank, and even fill the entire space inside the tube blank, playing a role in lubrication and cooling, reducing the friction between the forming head assembly and the inner wall of the tube blank, preventing the formation of high temperature, and extending the service life of the forming head assembly.

[0032] (8) This application also designs a circulating cooling structure for the tube shrinking die core. Preferably, it is connected to an external cooling source through the liquid inlet hole, and then the coolant is introduced along the spiral channel and the liquid outlet hole, which can effectively reduce the temperature of the tube shrinking die core, lubricate the contact part between the die core and the outer wall of the tube blank, reduce the tube shrinking resistance, reduce the wear of the die core cavity caused by friction, extend the service life of the die core, and also achieve lubrication and cooling of the outer wall of the tube blank. The lubrication and cooling position is the position with the highest heat and pressure intensity. Therefore, it can play a good cooling role in the most vulnerable position of the equal-wall tube shrinking position of the tube blank within the forming range of the tube blank, achieving the effect of simultaneous cooling of the inner and outer walls of the tube blank and truly improving the quality of the tube finished product. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic structural diagram of the mandrel structure of the first preferred embodiment of the present invention;

[0034] Figure 2 Schematic diagram of the disassembly of the mold mandrel and the pipe shrinking die core in the first preferred embodiment of the present invention;

[0035] Figure 3 is Figure 2 Enlarged schematic diagram of location A in

[0036] Figure 4 Schematic diagram of the disassembly structure of the mold mandrel in the first preferred embodiment of the present invention;

[0037] Figure 5 Cross-sectional schematic diagram of the mold mandrel in the first preferred embodiment of the present invention;

[0038] Figure 6 Schematic diagram of the disassembly structure of the mold mandrel from another angle in the first preferred embodiment of the present invention;

[0039] Figure 7 Schematic diagram of the structure of the pipe shrinking die core in the first preferred embodiment of the present invention;

[0040] Figure 8 Schematic diagram of the structure of the pipe shrinking die core from another angle in the first preferred embodiment of the present invention;

[0041] Figure 9 Cross-sectional schematic diagram of the pipe shrinking die core in the first preferred embodiment of the present invention;

[0042] Figure 10 Schematic diagram of the structure after the assembly of the die core structure in the first preferred embodiment of the present invention and the inner support structure of the binary unit;

[0043] Figure 11 is Figure 10 Cross-sectional structure schematic diagram of

[0044] Figure 12 is Figure 11 Enlarged schematic diagram of location B in

[0045] Figure 13 Schematic diagram of the structure of the equal-wall pipe shrinking die in the second preferred embodiment of the present invention.

[0046] In the figure: 100, the die core structure; 1, the die core bar; 11, the core bar body; 111, the coolant inlet chamber; 1111, the horizontal inlet chamber; 1112, the radial inlet chamber; 1113, the annular groove; 12, the forming head; 121, the first connecting section; 1211, the coolant diversion channel; 122, the second connecting section; 1221, the cooling groove; 1222, the coolant output hole; 1223, the liquid outlet channel; 12231, the liquid outlet hole; 12232, the annular groove; 123, the third connecting section; 1231, the coolant diversion channel; 124, the connecting piece; 1241, the annular groove; 1242, the radial groove; 2, the pipe shrinking die core; 21, the spiral channel; 22, the inlet hole; 23, the outlet hole; 24, the tapered section; 25, the straight barrel section; 200, the binary unit; 300, the binary unit; 400, the driving mechanism; G, the tube blank; L, the cooling source; L1, the first coolant outlet channel; L2, the second coolant outlet channel. Detailed implementation mode

[0047] Next, in combination with the accompanying drawings and the detailed implementation mode, the present invention will be further described. It should be noted that, on the premise of no conflict, the following described embodiments or technical features can be combined arbitrarily to form new embodiments.

[0048] Embodiment 1

[0049] As Figure 1-12 shown, a die core structure 100 with uniform and rapid cooling function includes a pipe shrinking die core 2 for reducing the diameter of the tube blank G and a die core bar 1 for keeping the wall thickness of the reduced-diameter tube blank G uniform. The pipe shrinking die core 2 is arranged on the outer wall of the tube blank G, and the die core bar 1 is arranged on the inner wall of the tube blank G.

[0050] Among them, one end of the die core bar 1 is the forming end, and the other end is the fixed end. The forming end of the die core bar 1 is sequentially divided into a first connecting section 121, a second connecting section 122 and a third connecting section 123 from the outside to the inside. A plurality of coolant diversion channels 1211 are opened in the first connecting section 121 near the outside. A cooling groove 1221 is recessed in the second connecting section 122 in the middle position. A coolant output hole 1222 is arranged at the bottom of the cooling groove 1221. A plurality of coolant diversion channels 1231 are opened in the third connecting section 123 near the inside. A hollow coolant inlet chamber 111 is arranged inside the die core bar 1, and the coolant inlet chamber 111 is communicated with the coolant output hole 1222 and / or the coolant diversion channels 1211 / 1231.

[0051] The present application strengthens lubrication and cooling at the forming positions of the mandrel forming end, die core, and tube blank material where friction, high temperature, wear, and deformation are most likely to occur. By improving the layout structure of the cooling channels, on the premise of not affecting the implementation of the equal-wall tube shrinking process of the mold, a circulating cooling channel is introduced at the forming end of the mold mandrel 1, extending the circulation path of the overall cooling channel, and deeply cooling and lubricating the first / second / third connection segments 121 / 122 / 123 at the forming position of the mandrel, the die core, the inner wall of the middle part of the tube blank G, and the inner walls at both ends of the tube blank G, effectively improving the uniformity of cooling, ensuring that the cooling speed of the material in the mold is consistent. This uniform cooling effectively avoids defects such as shrinkage holes, warping, and increased internal stress in the product, improving the finished product quality. In addition, the lubrication and cooling of the die core structure 100 are uniform, shortening the cooling time, thereby improving the cooling efficiency. At the same time, the coolant reduces the friction between the forming head assembly, the die core, and the tube blank, reducing production costs; at the same time, it extends the service life of the mold, avoiding defects such as accelerated wear and deformation of the mold material caused by excessive local temperature of the mold and shortening the service life of the mold. The coolant injected into the cooling channel of the present invention, in addition to the commonly used coolants in the art, includes but is not limited to lubricating fluids with similar functions, or a lubricating and high-temperature-resistant formula is added to the coolant to make it have both cooling and lubricating functions, which also falls within the scope of protection of the concept of the present invention.

[0052] As a further preferred solution, the mold mandrel 1 includes a mandrel body 11 and a forming head 12 detachably connected to the forming end of the mandrel body 11. The forming head 12 includes the first connection segment 121, the second connection segment 122, and the third connection segment 123. The first connection segment 121, the second connection segment 122, and the third connection segment 123 are of a split structure and are respectively detachably sleeved on the mandrel body 11.

[0053] The present application designs the mold mandrel into multiple connecting components, installs each connecting component on the forming end of the mold mandrel 1 in a detachable manner, can realize the connection and communication between each cooling channel, and is also convenient for rapid repair, replacement, and maintenance in the later stage.

[0054] As a further preferred solution, the outer diameter of the periphery of the first connection segment 121 is equal to the outer diameter of the periphery of the third connection segment 123, and the outer diameter of the periphery of the second connection segment 122 is smaller than the outer diameter of the periphery of the first connection segment 121; the maximum outer wall surface of the first connection segment 121 and the maximum outer wall surface of the third connection segment 123 are guiding and deviation-correcting surfaces for keeping the wall thickness of the reduced-diameter pipe uniform. This guiding and deviation-correcting surface is the main pressure-receiving surface during the equal-wall tube shrinking process. In this structure, the coolant groove is designed at the middle position. During the equal-wall tube shrinking process, the tube blank G is lubricated and cooled while being pressed, improving the lubrication and cooling effect, and effectively avoiding defects such as shrinkage holes, warping, and increased internal stress in the product, improving the finished product quality.

[0055] As a further preferred solution, in this embodiment, the coolant inlet chamber 111 on the mandrel body 11 includes a horizontal inlet chamber 1111 horizontally arranged inside the die mandrel 1, a radially distributed inlet chamber 1112 connected to the outlet end of the horizontal inlet chamber 1111, and an annular groove 1113 arranged on the outer surface of the die mandrel; the horizontal inlet chamber 1111, the radially distributed inlet chamber 1112, and the annular groove 1113 are communicated in sequence, and the annular groove 1113 is communicated with the coolant output hole 1222 and / or the coolant diversion channel 1231.

[0056] As Figure 12 shown, by improving the structure of the mandrel body 11 and designing a connected cooling channel in its internal structure and end part, the present application can introduce an external cooling source L to a key part that cannot effectively reach the forming end of the die mandrel 1, and then split it into a coolant outlet channel one L1 and a coolant outlet channel two L2, so as to achieve the overall lubrication and cooling effects.

[0057] As a further preferred solution, a liquid outlet channel 1223 is further opened at the bottom of the cooling groove 1221 of the second connection section 122. The liquid outlet channel 1223 includes radially distributed liquid outlet holes 12231 and an annular groove 12232 arranged on the side wall. The liquid outlet holes 12231 are communicated with the annular groove 12232, and the annular groove 12232 is communicated with the coolant diversion channel 1211 of the first connection section 121. Adding a liquid outlet channel at the bottom of the cooling groove 1221 can extend the overall cooling channel, reduce the temperature of the die mandrel 1, effectively improve the lubrication and cooling effects, reduce the friction between the forming head and the inner wall of the tube blank, and enable the coolant to directly reach the contact part between the forming head and the tube blank.

[0058] As a further preferred solution, the first connection section 121 is in a conical shape, the diameter of the first connection section 121 gradually narrows from the inside to the outside, and each of the coolant diversion channels 1211 located in the first connection section 121 is evenly distributed inside the first connection section 121, and the coolant diversion channels are radially inclined and gradually narrow towards the outside. Designing the outer first connection section 121 into a conical shape and the position of its conical narrowing close to the middle of the tube blank G enables the coolant diversion channels inside the first connection section 121 to gradually narrow inwards along the flowing direction of the cooling channel, which can avoid the reverse flow of the cooling channel, improve the flow smoothness of the cooling channel, and improve the cooling effect.

[0059] As a further preferred solution, a connecting piece 124 is further provided on the outer side of the first connecting section 121. An annular groove 1241 and radially grooved grooves 1242 connected to the annular groove are provided on the side wall of the connecting piece 124; the output ends of the respective coolant diversion channels 1211 on the first connecting section 121 are distributed on the annular groove 1241, and the lubricating coolant ejected from the radially grooved grooves 1242 enables the lubricating coolant to directly reach the contact part between the forming head and the tube blank, and cools the inner wall of the tube blank G.

[0060] In this application, by adding the connecting piece 124, the connecting piece 124 has two functions. One is to fix the installation positions of the first connecting section 121, the second connecting section 122, and the third connecting section 123. The inner ring of the connecting piece 124 is provided with threads and is fixedly connected to the end of the mandrel body 11 by threads to achieve rapid assembly. The other is to provide radially grooved grooves 1242 on the connecting piece 124, which can effectively spray the coolant onto the inner walls at both ends of the tube blank G from multiple angles and fill the entire space inside the tube blank G.

[0061] As a further preferred solution, a spiral channel 21 is provided on the outer wall of the tube-reducing die core 2. Liquid inlet holes 22 and liquid outlet holes 23 are provided at both ends of the spiral channel 21. The liquid inlet hole 22 is communicated with a cooling source, and the coolant flowing out from the liquid outlet hole 23 is used to cool the outer wall of the tube blank G.

[0062] In addition, this application also designs a circulating cooling structure for the tube-reducing die core. Preferably, an external cooling source is communicated with the liquid inlet hole 22, and then the coolant is introduced along with the spiral channel 21 and the liquid outlet hole, which can effectively reduce the temperature of the tube-reducing die core 2 and achieve cooling of the outer wall of the tube blank G. The cooling position is the position with the highest heat and pressure resistance. Therefore, it can play a good cooling role in the weakest position within the equal-wall tube-reducing forming range of the tube blank G, achieving the effect of simultaneous cooling of the inner wall and the outer wall of the tube blank G and truly improving the quality of the finished tube.

[0063] As a further preferred solution, the inner cavity of the tube-reducing die core 2 includes a tapered section 24 and a straight cylinder section 25 connected to the narrow end position of the tapered section 24. The minimum inner diameter of the tapered section 24 is larger than the outer diameter of the tube blank G, and the inner diameter of the straight cylinder section 25 is equivalent to the outer diameter of the tube blank G; in the open die state, the forming end of the tube-reducing die core 2 is located in the straight cylinder section 25 of the tube-reducing die core 2, and the distance between the outer surface of the forming end of the die mandrel and the inner wall of the straight cylinder section 25 of the tube-reducing die core is the same as the wall thickness of the tube blank after tube reduction.

[0064] Embodiment 2

[0065] As Figure 13 shown, an equal-wall tube-reducing die includes a binary unit 200, a binary unit 300, and the die core structure 100 as described in Embodiment 1, asFigure 1-12 as shown;

[0066] The binary unit 300 is arranged outside the unary unit 200. The unary unit 200 and the binary unit 300 are respectively slidably mounted on the pipe shrinking device, and the unary unit 200 and the binary unit 300 have a synchronous sliding process and their respective independent sliding processes;

[0067] Among them, the die mandrel 1 in the die core structure 100 is mounted on the unary unit 200 and can move synchronously with the unary unit 200 for reducing the diameter of the tube blank G; the fixed end of the pipe shrinking die core 2 in the die core structure 100 is fixedly mounted on the binary unit 300 and can move synchronously with the binary unit 300 for keeping the wall thickness of the shrunk tube blank G uniform; the unary unit 200 and the binary unit 300 are connected with a driving mechanism 400, and the driving mechanism 400 drives the unary and binary units 300 to slide respectively, and drives the unary unit 200 to move through the binary unit 300 to complete the pipe shrinking forming;

[0068] The pipe shrinking die core 2 and the die mandrel 1 realize equal-wall diameter reduction of the metal pipe under the sliding fit of the unary unit 200 and the binary unit 300.

[0069] The equal-wall pipe shrinking process of this equal-wall pipe shrinking die is as follows:

[0070] Step 1: Place the tube blank G in the fixture of the pipe shrinking device, mainly fix the middle part of the tube blank G in the fixture; the pipe shrinking device clamps the middle shape of the tube blank G under the control of the numerical control system, and the driving mechanisms 400 on the left and right sides push the pipe shrinking die under the system control to start shrinking the tube blank G.

[0071] Step 2: The driving mechanism 400 pushes the pipe shrinking dies on both sides towards the tube blank G, so that the die mandrel 1 and the pipe shrinking die core 2 also move towards the tube blank G; when the pipe shrinking die core 2 contacts the tube blank G, due to the resistance of the tube blank G entering the die, the unary unit 200 slides backward under the action of the resistance, and after the sliding distance reaches the binary distance, it fits with the binary unit 300; at this time, the forming end of the die mandrel 1 extends into the tapered section 24 of the pipe shrinking die core 2. Since the gap here is larger than that in the straight cylinder section 25, the tube blank G can smoothly pass through the pipe shrinking die core 2 and enter the forming inner cavity when being introduced into the pipe shrinking die; during the process of the tube blank G entering the forming inner cavity, the wall thickness of the tube blank G increases due to the extrusion of the pipe shrinking die core 2 and the die mandrel 1, making the thickness of the tube blank G become a wavy irregular shape.

[0072] Step 3: After the set length of the tube blank G completely enters the tube shrinking die, the binary unit 300 starts to perform a retracting action driven by the driving mechanism 400; at this time, the binary unit 200 will remain stationary due to the frictional force with the tube blank G. Under the retracting action of the binary unit 300, it is pulled apart to the binary distance. At the same time, the forming end of the die mandrel 1 is pulled back to the straight tube section 25 of the tube shrinking die core 2. This process is the binary action;

[0073] Step 4: The binary unit 300 continues to retract, driving the binary unit 200 to cause the tube shrinking die core 2 to start to retract as a whole. Since the gap between the forming end of the die mandrel 1 and the inner wall of the straight tube section 25 of the tube shrinking die core 2 is the same as the original wall thickness of the tube blank G, the retraction of the die mandrel 1 causes the increased wall thickness of the tube blank G to be retrimmed and thinned back to the original thickness;

[0074] Step 5: After the overall retracting action of the tube shrinking die core 2 is completed, the tube blank G returns to the original wall thickness and is smooth and flat as a whole. The lubrication and cooling systems are turned off, and the tube shrinking is completed.

[0075] During the entire tube shrinking process, especially in Step 4 when the tube blank G enters and exits the inside of the tube shrinking die core 2, the inner and outer walls of the tube blank G are lubricated and cooled through the die core structure 100 of the present invention to ensure the smooth progress of the tube shrinking process and protect the die.

[0076] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantive changes and substitutions made by those skilled in the art based on the present invention belong to the scope of protection required by the present invention.

Claims

1. A mold core structure with uniform and rapid cooling function, comprising a tube shrinking mold core for reducing the diameter of a tube blank and a mold core rod for maintaining a uniform wall thickness of the tube blank after the diameter reduction, wherein the tube shrinking mold core is arranged on the outer tube wall of the tube blank, and the mold core rod is arranged on the inner tube wall of the tube blank, characterized in that: One end of the mold core rod is a molding end, and the other end of the mold core rod is a fixed end. The molding end of the mold core rod is divided into a first connecting section, a second connecting section and a third connecting section from the outside to the inside. The first connecting section close to the outside is provided with a plurality of coolant guide channels, and the second connecting section located in the middle is recessed with a cooling groove, and a coolant output hole is provided at the bottom of the cooling groove. The third connecting section close to the inside is provided with a plurality of coolant guide channels; a hollow coolant inlet chamber is provided inside the mold core rod, and the coolant inlet chamber is connected with the coolant output hole and / or the coolant guide channel to achieve lubrication and cooling of the molding end of the mold core rod.

2. The mold core structure with uniform and rapid cooling function according to claim 1, characterized in that: The mold core rod includes a core rod body and a molding head detachably connected to the molding end of the core rod body, the molding head includes the first connecting segment, the second connecting segment, and the third connecting segment. The first connecting segment, the second connecting segment, and the third connecting segment are split structures and are detachably mounted on the core rod body.

3. The mold core structure with uniform and rapid cooling function according to claim 1 or 2, characterized in that: The outer tube diameter of the first connecting section is equal to the outer tube diameter of the third connecting section, and the outer tube diameter of the second connecting section is smaller than the outer tube diameter of the first connecting section; the maximum outer wall surface of the first connecting section and the maximum outer wall surface of the third connecting section are guide correction surfaces, which are used to keep the wall thickness of the pipe after diameter reduction uniform.

4. The mold core structure with uniform and rapid cooling function according to claim 1 or 2, characterized in that: The coolant inlet chamber of the mold core rod includes a horizontal inlet chamber horizontally arranged inside the mold core rod, a radial inlet chamber connected to the outlet end of the horizontal inlet chamber, and an annular groove arranged on the outer surface of the mold core rod; the horizontal inlet chamber, the radial inlet chamber and the annular groove are connected in sequence, and the annular groove is connected to the coolant outlet hole and / or the coolant guide channel.

5. The mold core structure with uniform and rapid cooling function according to claim 1 or 2, characterized in that: A liquid outlet channel is also provided at the bottom of the cooling groove of the second connecting section, and the liquid outlet channel includes radially distributed liquid outlet holes and an annular groove arranged on the side wall. The liquid outlet holes are connected to the annular groove, and the annular groove is connected to the coolant guide channel of the first connecting section.

6. The mold core structure with uniform and rapid cooling function according to claim 1 or 2, characterized in that: The first connecting section is cone-shaped, and the diameter of the first connecting section gradually narrows from the inside to the outside. The coolant guide channels located in the first connecting section are evenly distributed inside the first connecting section, and the coolant guide channels are radially inclined and gradually narrowed toward the outside.

7. The mold core structure with uniform and rapid cooling function according to claim 1 or 2, characterized in that: A connecting plate is also provided on the outer side of the first connecting section, and a side wall of the connecting plate is provided with an annular groove and a radial groove connected to the annular groove; the output ends of each coolant guide channel on the first connecting section are distributed on the annular groove, and the coolant flowing out of the radial groove is used to lubricate and cool the forming end of the mold core rod and the inner wall of the tube blank.

8. The mold core structure with uniform and rapid cooling function according to claim 1 or 2, characterized in that: The outer wall of the tube shrinking mold core is provided with a spiral channel, and liquid inlet holes and liquid outlet holes are provided at both ends of the spiral channel. The liquid inlet hole is connected to a cooling source, and the coolant flowing out of the liquid outlet hole is used to cool the outer wall of the tube shrinking mold core and the tube blank.

9. The mold core structure with uniform and rapid cooling function according to claim 8, characterized in that: The inner cavity of the tube reduction mold core includes a tapered section and a straight section connected to the narrow position of the tapered section, the minimum inner diameter of the tapered section is larger than the outer diameter of the tube blank, and the inner diameter of the straight section is equivalent to the outer diameter of the tube blank; in the mold opening state, the forming end of the tube reduction mold core is located in the straight section of the tube reduction mold core, and the distance between the outer surface of the forming end of the mold core rod and the inner wall of the straight section of the tube reduction mold core is the same as the wall thickness of the tube blank after tube reduction.

10. A uniform wall shrink tube mold, characterized in that: It comprises a unary unit and a binary unit, wherein the unary unit and the binary unit are respectively slidably mounted on the shrink tube device, and the unary unit and the binary unit have a synchronous sliding process and a respective independent sliding process; The equal-wall tube reduction mold also includes a mold core structure with uniform and rapid cooling function as described in any one of claims 1 to 9, wherein the mold core rod is installed on the one-dimensional unit to reduce the diameter of the tube blank, and the tube reduction mold core is installed on the binary unit to keep the wall thickness of the tube blank after diameter reduction uniform; the tube reduction mold core and the mold core rod realize equal-wall diameter reduction of the metal tube under the sliding cooperation of the one-dimensional unit and the binary unit.

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