Pneumatic capillary copper tube expander and expanding method

Abstract

The application discloses a pneumatic capillary copper pipe expanding machine and an expanding method, and relates to the technical field of pipe expanding equipment. The pneumatic capillary copper pipe expanding machine comprises a rack, a clamping and conveying device and a pipe expanding die device. The clamping and conveying device comprises a conveying cylinder and a clamping mechanism, and the clamping mechanism is provided with a pipe penetrating channel to clamp the capillary copper pipe. The pipe expanding die device comprises a pipe expanding fixing plate, a rotating disc, a rotating cylinder, a plurality of pipe expanding mechanisms and a blanking pipe, and the blanking pipe or one pipe expanding mechanism is coaxial with the pipe penetrating channel. The pipe expanding mechanism comprises a pipe expanding needle fixedly arranged on the rotating disc, the pipe expanding needle is gradually increased in diameter along a rotating direction, and an expanding guide assembly is arranged on the outer side of the pipe expanding needle and is driven to axially reciprocate by a push-pull cylinder. The application can directly expand the end of the capillary copper pipe, cancels a transition pipe, reduces a brazing point, thereby reducing the cost, preventing pipe blockage and fluorine leakage, and improving product quality. The application also discloses a pneumatic capillary copper pipe expanding method.

Description

Technical Field

[0001] This invention relates to the field of tube expanding equipment technology, and in particular to a pneumatic capillary copper tube expanding machine and expanding method. Background Technology

[0002] In the field of air conditioning and heating, a reliable connection between the copper tubes inside the radiator and the capillary tube of the distributor is crucial for ensuring system efficiency and long-term stable operation. Currently, the industry commonly uses the brazing of the distributor transition tube method. This method first requires connecting a slender capillary tube, typically with an inner diameter of about 2 mm, to a matching copper transition tube. This transition tube is then brazed to the main radiator circuit, which has an inner diameter of about 8.3 mm. This method is widely used in production due to its relatively simple processing equipment and low initial investment cost. However, the essence of this method is that it introduces an additional mechanical interface and two independent brazing connection points between the distributor capillary tube and the copper tubes inside the radiator. This makes the process complex and highly dependent on the quality of subsequent welding.

[0003] The existing technical solution has revealed several inherent and insurmountable defects in actual large-scale production, mainly manifested in the quality risks caused by the brazing process. First, due to the significant geometrical dimensional differences between the capillary tube of the distributor head and the transition tube, and between the transition tube and the copper tube inside the radiator, the molten solder is prone to uncontrollable flow in tiny gaps during brazing heating, causing partial or complete blockage of the capillary port, i.e., "tube blockage". Second, there may be incomplete or discontinuous welding at the welding point, leading to system seal failure and "fluorine leakage". A more serious challenge is that the above defects are difficult to identify efficiently and accurately during the finished product quality inspection stage; internal solder blockage cannot be detected by conventional visual inspection, while tiny fluorine leaks require complex leak detection procedures. This significantly increases the risk of defective products flowing into subsequent stages or even the final product, becoming a major unstable factor affecting the overall production yield.

[0004] Unreliable brazing quality leading to pipe blockage and refrigerant leakage poses a direct threat to the final performance and lifespan of air conditioning systems. Pipe blockage causes uneven refrigerant flow distribution, severely reducing heat exchange efficiency and potentially causing localized abnormal icing, system pressure imbalance, and even stress concentration leading to pipe breakage under long-term operation. Refrigerant leakage directly results in refrigerant loss, causing system energy efficiency degradation and increased operating costs. When these problems surface in the after-sales stage, repair costs are high and the process is cumbersome, often requiring disassembly of most system components for troubleshooting and resoldering, significantly increasing maintenance costs. Although the industry has attempted to alleviate the problem by optimizing brazing parameters, improving operator skills, or introducing more expensive automated welding equipment, none of these methods have fundamentally eliminated the redundant component of the transition pipe and the two additional weld points it introduces. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a pneumatic capillary copper tube expander and expander method, which can expand one end of the capillary copper tube, eliminate the existence of the original transition tube, reduce production costs, reduce the number of brazing points, prevent tube blockage and refrigerant leakage, and improve product quality.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] A pneumatic capillary copper tube expander includes a frame; the frame is equipped with a horizontally and relatively opposite clamping and conveying device and an expanding punch device.

[0008] The clamping and conveying device includes a horizontally arranged conveying cylinder. A clamping mechanism is installed on the piston rod of the conveying cylinder. The clamping mechanism is located close to the tube expanding punch device. The clamping mechanism has a tube-passing channel with both ends horizontally connected inside. The clamping mechanism is used to clamp and fix the tube expanding end of the capillary copper tube that extends through the tube-passing channel.

[0009] The tube expanding punch device includes a tube expanding fixing plate. A rotary disk is rotatably mounted on one side of the tube expanding fixing plate near the clamping mechanism. The rotary disk is vertically arranged and connected to a rotary cylinder that drives it to rotate intermittently. Several tube expanding mechanisms and at least one feeding pipe are horizontally mounted on the rotary disk. Several tube expanding mechanisms and the feeding pipe are located in the same circumference and are spaced apart. The feeding pipe located at the top of the rotary disk or one of the tube expanding mechanisms is coaxially arranged with the tube through channel.

[0010] The tube expanding mechanism includes tube expanding needles fixed on the rotary table; along the rotation direction of the rotary table, the diameter of the tube expanding needles located downstream of the feed tube increases sequentially; a tube expanding guide assembly is coaxially slidably arranged on the outer side of the tube expanding needle, and a push-pull cylinder is installed on the other side of the tube expanding fixing plate, the push-pull cylinder being used to drive the tube expanding guide assembly to reciprocate along its axial direction.

[0011] Preferably, the piston rod of the push-pull cylinder is equipped with a plurality of push rods and is arranged toward the expansion tube guide assembly, the push rods being used to abut against the corresponding expansion tube guide assembly;

[0012] The rotary table is fixedly connected to the guide plate via a rotary shaft. The guide plate is coaxial with the rotary table. The expansion tube guide assembly passes through the guide plate and a guide return spring abuts against it. The other end of the rotary shaft is connected to the rotary cylinder via a one-way clutch.

[0013] Preferably, the tube expanding guide assembly includes a reset guide sleeve coaxially slidably disposed on the outside of the tube expanding needle, and the reset guide sleeve and the guide plate are abutted by the guide reset spring;

[0014] A needle guide sleeve is installed on the outer side of the reset guide sleeve, and the outer end of the tube expander always passes through the needle guide sleeve and is located outside it; a tube limiting sleeve is installed on the outer side of the needle guide sleeve, and an elastic bushing is installed in the inner cavity of the tube limiting sleeve; the inner diameter of the elastic bushing increases with the diameter of the tube expander.

[0015] Preferably, a horizontally sliding tie rod is provided through the expansion pipe fixing plate. The tie rod is located on the outer side of the rotary table along its radial direction. One end of the tie rod is connected to the piston rod of the push-pull cylinder through a push-pull mounting plate, and the other end of the tie rod extends axially to the outer side of the reset guide sleeve. The tie rod is coaxially arranged with the push-pull cylinder.

[0016] A plurality of push rods are mounted on the push-pull mounting plate, and the plurality of push rods are arranged at equal intervals along the circumference of the reset guide sleeve.

[0017] Preferably, the outer circumferential surface of the rotary table is provided with ratchet teeth, and the expansion tube fixing plate is equipped with a pawl that elastically abuts against the ratchet teeth; the pawl and the ratchet teeth cooperate to limit the rotary table to rotate unidirectionally around its axis;

[0018] The outer circumferential surface of the rotary table abuts against the damping rubber strip. One end of the damping rubber strip is fixedly connected to the expansion pipe fixing plate, and the other end of the damping rubber strip is threadedly connected to the expansion pipe fixing plate. The abutment pressure between the damping rubber strip and the rotary table is adjustable.

[0019] Preferably, the push-pull cylinder is connected to one outlet of the reversing valve via a push-pull air passage; the rotary cylinder is connected to the other outlet of the reversing valve via a rotary air passage; the inlet of the reversing valve is connected to an external high-pressure air source; and a one-way sequence valve is provided on both the push-pull air passage and the rotary air passage.

[0020] Preferably, the clamping mechanism includes a vertically arranged clamping mounting plate, one side of which is fixedly connected to the piston rod of the conveying cylinder, and the clamping mounting plate is horizontally slidably arranged on the frame;

[0021] A pneumatic clamping seat is installed on the other side of the clamping mounting plate, and the through-tube channel passes through the clamping mounting plate, the pneumatic clamping seat and the conveying cylinder; the through-tube channel is coaxially arranged with the piston rod of the conveying cylinder.

[0022] Preferably, the pneumatic clamping seat includes a seat body, and a reciprocating piston is disposed inside the seat body. The outer end of the piston is configured as an outwardly expanding cone. A plurality of clamping wedges adapted to the piston are installed on the outer end of the piston, and the inner sides of the plurality of clamping wedges together form the tube passage.

[0023] The inner end of the clamping wedge is set as an inwardly tapered shape, and a clamping bushing adapted to it is installed on the inner side of the clamping wedge. The inner diameter of the clamping bushing is larger than the through-pipe channel, and a transition guide slope is provided inside the clamping bushing.

[0024] Preferably, a counterweight mechanism is provided between the clamping mounting plate and the frame;

[0025] The counterweight mechanism includes a counterweight frame vertically mounted on the frame, with two reversing wheels rotatably mounted on the counterweight frame, and a counterweight chain mounted on each of the two reversing wheels; one end of the counterweight chain passes over one of the reversing wheels and connects to the top of the clamping mounting plate, and the other end of the counterweight chain passes over the other reversing wheel and connects to the counterweight box.

[0026] The pneumatic capillary copper tube expansion method utilizes the pneumatic capillary copper tube expander described above; the expansion method includes the following steps:

[0027] S1. Pass the capillary copper tube through the tube-passing channel and extend it out of the clamping mechanism;

[0028] S2. The rotary cylinder drives the rotary table to rotate, so that the first tube expanding mechanism located downstream of the feeding tube corresponds to the position of the capillary copper tube, and the capillary copper tube moves along its axial direction to abut the tube expanding needle of the current tube expanding mechanism.

[0029] S3, The clamping mechanism clamps and fixes the capillary copper tube;

[0030] S4. The push-pull cylinder drives the corresponding tube expansion guide assembly to move along its axis toward the clamping mechanism and abut against it.

[0031] S5. The conveying cylinder drives the clamping mechanism to continuously apply pressure to the tube expansion guide assembly, causing the tube expansion guide assembly to move in the opposite direction along its axis, while simultaneously moving the capillary copper tube together. The capillary copper tube is inserted by the tube expansion needle to complete the tube expansion.

[0032] S6. The conveying cylinder drives the capillary copper tube back to its initial position through the clamping mechanism, and the push-pull cylinder drives the tube expansion guide assembly back to its initial position.

[0033] S7. The rotary cylinder drives the rotary table to rotate, so that the next tube expansion mechanism corresponds to the position of the capillary copper tube.

[0034] S8. Repeat S4 to S7 until the capillary copper tube passes through all the tube expanding mechanisms in sequence and the tube expansion is completed.

[0035] S9. The rotary cylinder drives the rotary table to rotate, so that the feeding tube is aligned with the expanded capillary copper tube. The clamping mechanism releases the capillary copper tube, and the capillary copper tube is moved out of the feeding tube.

[0036] After adopting the above technical solution, the beneficial effects of the present invention are:

[0037] This application discloses a pneumatic capillary copper tube expander and a tube expanding method. The pneumatic capillary copper tube expander includes a frame, on which a clamping and conveying device and a tube expanding punch device are mounted. The clamping and conveying device includes a conveying cylinder, and a clamping mechanism is mounted on the piston rod of the conveying cylinder. The clamping mechanism has a tube-passing channel inside and is used to clamp and fix the capillary copper tube. The tube expanding punch device includes a tube expanding fixing plate, on which a rotary disk is rotatably mounted. The rotary disk is connected to a rotary cylinder that drives its intermittent rotation. Several tube expanding mechanisms and at least one feeding tube are mounted on the rotary disk. Each tube expanding mechanism includes a tube expanding needle. A tube expanding guide assembly is coaxially and slidably arranged on the outer side of the tube expanding needle. A push-pull cylinder is mounted on the other side of the tube expanding fixing plate and is used to drive the tube expanding guide assembly to reciprocate along its axial direction.

[0038] This application utilizes a multi-step progressive tube expansion process with multiple tube-expanding pins of progressively increasing diameter, achieving direct forming of the capillary copper tube end. This eliminates the need for a transition tube required in traditional processes and reduces one welding point, fundamentally eliminating the risks of tube blockage and refrigerant leakage caused by brazing. Simultaneously, the rotary table integrates multiple tube-expanding mechanisms and a feeding tube, completing station switching and processing cycles through intermittent rotation. This enables continuous processing and feeding of workpieces in a single clamping operation, improving production efficiency and operational convenience. Secondly, a pneumatic system consisting of a conveying cylinder, a push-pull cylinder, and a rotary cylinder drives the main movements, resulting in a stable structure, rapid response, low maintenance costs, and ease of production promotion. Finally, the entire processing is completed under the firm fixation of the clamping mechanism and the precise guidance of the tube-expanding guide assembly, effectively preventing deformation and deflection of the slender, soft copper tube during the expansion process, ensuring forming quality. Attached Figure Description

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] Figure 1 This is a schematic diagram of the structure of the pneumatic capillary copper tube expander according to Embodiment 1 of the present invention;

[0041] Figure 2 yes Figure 1 Schematic diagram of the expansion tube punch device;

[0042] Figure 3 yes Figure 2 Enlarged view of part B in the image;

[0043] Figure 4 yes Figure 2 A schematic diagram of the structure of the feed tube in the expansion punch device when it is at the bottom;

[0044] Figure 5 yes Figure 1 Enlarged view of part A;

[0045] Figure 6 yes Figure 1 Schematic diagram of the middle clamping and conveying device;

[0046] Figure 7 yes Figure 6 Schematic diagram of the air circuit connection of the clamping mechanism;

[0047] Figure 8 This is a schematic diagram of the rotary table in an embodiment of the present invention;

[0048] Figure 9 This is a control principle diagram of the tube expanding punch device in an embodiment of the present invention;

[0049] Figure 10 This is a schematic diagram of the structure of the capillary copper tube after expansion in an embodiment of the present invention;

[0050] In the picture:

[0051] 1. Rack;

[0052] 2. Clamping and conveying device; 21. Conveying cylinder; 22. Clamping mechanism; 221. Pipe passage; 222. Clamping mounting plate; 223. Pneumatic clamping seat; 2231. Seat body; 2232. Piston; 2233. Clamping wedge; 2234. Clamping bushing;

[0053] 3. Expanding punch device; 31. Expanding fixing plate; 32. Rotary table; 321. Rotary shaft; 322. Guide plate; 323. Guide return spring; 324. One-way clutch; 325. Racket tooth; 326. Pawl; 33. Rotary cylinder; 34. Expanding mechanism; 341. Expanding needle; 342. Expanding guide assembly; 3421. Return guide sleeve; 3422. Needle guide sleeve; 3423. Tube limiting sleeve; 3424. Elastic bushing; 35. Feed tube; 36. Push-pull cylinder; 361. Push rod; 362. Pull rod; 363. Push-pull mounting plate; 364. Reversing valve; 365. One-way sequence valve; 37. Damping rubber strip;

[0054] 4. Capillary copper tube;

[0055] 5. Counterweight mechanism; 51. Counterweight frame; 52. Reversing wheel; 53. Counterweight chain; 54. Counterweight box. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0057] Example 1

[0058] like Figures 1 to 10 As shown in the figure, the present invention discloses a pneumatic capillary copper tube expander, including a frame 1; a horizontally and relatively arranged clamping and conveying device 2 and an expanding punch device 3 are installed on the frame 1.

[0059] The clamping and conveying device 2 includes a horizontally arranged conveying cylinder 21. A clamping mechanism 22 is installed on the piston rod of the conveying cylinder 21. The clamping mechanism 22 is located near the tube expanding punch device 3. The clamping mechanism 22 has a tube-through channel 221 with both ends horizontally connected inside. The clamping mechanism 22 is used to clamp and fix the tube expanding end of the capillary copper tube 4 that extends through the tube-through channel 221.

[0060] The tube expanding punch device 3 includes a tube expanding fixing plate 31. A rotary disk 32 is rotatably mounted on one side of the tube expanding fixing plate 31 near the clamping mechanism 22. The rotary disk 32 is vertically arranged and connected to a rotary cylinder 33 that drives it to rotate intermittently. Several tube expanding mechanisms 34 and at least one unloading pipe 35 are horizontally mounted on the rotary disk 32. The several tube expanding mechanisms 34 and the unloading pipe 35 are located in the same circumference and are spaced apart. The unloading pipe 35 or one of the tube expanding mechanisms 34 located at the top of the rotary disk 32 is coaxially arranged with the tube passage 221.

[0061] The tube expanding mechanism 34 includes a tube expanding needle 341 fixed on the rotary table 32; along the rotation direction of the rotary table 32, the diameter of the tube expanding needle 341 located downstream of the feed tube 35 increases sequentially; a tube expanding guide assembly 342 is slidably arranged coaxially on the outer side of the tube expanding needle 341, and a push-pull cylinder 36 is installed on the other side of the tube expanding fixing plate 31. The push-pull cylinder 36 is used to drive the tube expanding guide assembly 342 to reciprocate along its axial direction.

[0062] The capillary copper tube 4 to be processed is passed through the tube-passing channel 221 in the clamping and conveying device 2, so that its expanded end extends out of the clamping mechanism 22. After the equipment is started, the rotary cylinder 33 drives the rotary table 32 to rotate intermittently, so that the first of the multiple tube-expanding mechanisms 34 arranged circumferentially on it (i.e., the tube-expanding needle 341 with the smallest diameter) rotates to a working position coaxial with the tube-passing channel 221. At this time, the clamping mechanism 22 is operated to clamp and fix the capillary copper tube 4. Subsequently, the push-pull cylinder 36 is actuated, pushing the tube-expanding guide assembly 342 corresponding to the current work position to move axially toward the clamping mechanism 22 until it abuts against it, providing precise guidance for the introduction of the capillary copper tube 4. Then, the conveying cylinder 21 drives the entire clamping mechanism 22 and the capillary copper tube 4 it clamps to feed toward the tube-expanding punch device 3. During this process, the end of the capillary copper tube 4, guided by the tube expanding guide assembly 342, is smoothly and coaxially inserted into the tube expanding needle 341 at the current station. With continuous feeding, the tube expanding needle 341 gradually expands the inner hole of the capillary copper tube 4, completing one tube expansion. After one tube expansion is completed, the conveying cylinder 21 drives the clamping mechanism 22 and the capillary copper tube 4 to return to the initial position, and the push-pull cylinder 36 also drives the tube expanding guide assembly 342 to reset. Then, the rotary cylinder 33 actuates again, driving the rotary table 32 to rotate one station, so that the next tube expanding needle 341 with a larger diameter is aligned with the tube passage 221. Repeating the above clamping, guiding, feeding expansion, retraction, and mold changing process, the end of the capillary copper tube 4 is continuously and gradually expanded and deformed by multiple tube expanding needles 341 arranged from thin to thick. After the last (largest diameter) tube expansion station is completed, the rotary table 32 rotates, aligning the unloading tube 35 on it with the workpiece. The clamping mechanism 22 is released, and the processed capillary copper tube 4 can be taken out through the unloading tube 35, thus completing the entire process of a capillary copper tube 4 from clamping, multi-step tube expansion to unloading.

[0063] In the above process, the pneumatic capillary copper tube expander of this embodiment achieves high-ratio (e.g., expanding from an inner diameter of 2.0 mm to over 8.3 mm) precision forming of one end of a slender, flexible capillary copper tube 4 through a multi-step progressive tube expansion process. By integrating multiple expanding needles 341 with increasing diameters using a rotary table 32, the large deformation that is difficult to complete in one step is decomposed into multiple consecutive small deformations, effectively reducing the resistance of a single expansion and avoiding the risk of instability, wrinkling, or breakage of the capillary copper tube 4 due to excessive instantaneous force. This solves the technical bottleneck of traditional processes that cannot directly form the tube. Secondly, it fundamentally eliminates the traditional liquid distribution transition pipe component in air conditioning refrigeration pipe connections. Since the capillary copper tube 4 can be directly brazed to the radiator copper tube after expansion, the additional brazing points required by the transition tube are eliminated. This not only simplifies the pipeline structure, but also eliminates the quality risks such as the flow of solder at complex joints clogging the capillary tube (i.e., "pipe blockage") and the sealing failure caused by the increase of solder points (i.e., "refrigerant leakage"), which significantly improves the reliability and long-term stability of the air conditioning system connection and achieves a qualitative leap in product quality.

[0064] Preferably, there are nine tube expanding mechanisms 34 and one feeding tube 35, which are arranged equidistantly on the rotary table 32. Therefore, when the capillary copper tube 4 is expanded from an inner diameter of 2.0 mm to 8.3 mm, it needs to go through nine tube expanding procedures. The tube expanding sequence is: 2.0 mm, 2.5 mm, 3.0 mm, 3.6 mm, 4.3 mm, 5.1 mm, 6.0 mm, 6.9 mm, 7.7 mm, and 8.3 mm.

[0065] During the tube expansion process, the coordinated action of the clamping and conveying device 2 and the tube expansion punch device 3 in this embodiment is controlled by a pneumatic circuit (such as push-pull cylinder 36, conveying cylinder 21, and rotary cylinder 33) and a control system. This achieves automatic clamping, sequential feeding expansion, automatic mold changing, and unloading of the capillary copper tube 4. Manual personnel are only responsible for loading and unloading, greatly reducing labor intensity and improving the consistency of production cycle and processing accuracy. Furthermore, it directly saves on the material cost and warehousing management cost of the transition tube itself. Simultaneously, by reducing the critical brazing process, it reduces reliance on skilled welders, solder, and related energy consumption, simplifying the production process and reducing overall production costs. Finally, the structural design is compact and reasonable; the cooperation between the tube expansion guide component 342 and the push-pull cylinder 36 ensures the alignment of the workpiece and the mold during each tube expansion; the rotary table 32 ensures accurate indexing and smooth rotation; and the clamping mechanism 22 ensures that the soft copper tube does not deform during clamping. These designs collectively guarantee the reliability of equipment operation and the high quality of tube expansion forming.

[0066] In this embodiment, a plurality of push rods 361 are mounted on the piston rod of the push-pull cylinder 36 and are positioned toward the expansion tube guide assembly 342. The push rods 361 are used to abut against the corresponding expansion tube guide assembly 342. The rotary disk 32 is fixedly connected to the guide disk 322 via the rotary shaft 321. The guide disk 322 is coaxially arranged with the rotary disk 32. The expansion tube guide assembly 342 passes through the guide disk 322 and a guide return spring 323 abuts against it. The other end of the rotary shaft 321 is connected to the rotary cylinder 33 via a one-way clutch 324.

[0067] By connecting the piston rod of the push-pull cylinder 36 to several push rods 361, and making the push rods 361 act directly on the tube expander guide assembly 342, rigid power transmission and positioning are achieved. This ensures that during the tube expander process, the push-pull cylinder 36 can accurately and synchronously push the tube expander guide assembly 342 corresponding to the current station through the push rods 361, making it move precisely along the axial direction. This provides a stable and reliable guiding reference for the introduction and withdrawal of the capillary copper tube 4, effectively ensuring the coaxiality between the tube expander needle 341 and the capillary copper tube 4.

[0068] The rotary table 32 is fixedly connected to an independent guide plate 322 via a rotary shaft 321, and the expansion guide assembly 342 passes through the guide plate 322 and elastically abuts against it with the help of a guide return spring 323, achieving relatively independent guiding and resetting. On the one hand, the guide plate 322 provides a unified and high-precision installation and sliding reference for all expansion guide assemblies 342, ensuring the consistency of the guide axis at each station; on the other hand, the guide return spring 323 provides the expansion guide assembly 342 with an elastic force for automatic resetting. When the push-pull cylinder 36 applies force through the push rod 361, the expansion guide assembly 342 compresses the guide return spring 323 and moves forward; when the thrust is removed, under the elastic force of the guide return spring 323, the expansion guide assembly 342 can automatically and smoothly return to its initial position. This simplifies the resetting structure and improves the response speed and reliability of the action.

[0069] The rotary shaft 321 is connected to the rotary cylinder 33 via a one-way clutch 324, forming the intermittent indexing drive structure in this embodiment. The presence of the one-way clutch 324 ensures that the power of the rotary cylinder 33 can only be transmitted to the rotary shaft 321 in one direction, thereby driving the rotary table 32 and the guide plate 322 to rotate in one direction and with a defined intermittent motion. This effectively prevents the rotary table 32 from reverse movement under external interference or system pressure fluctuations, ensuring the absolute accuracy of the mold changing station. From the rotary cylinder 33 and the one-way clutch 324 to the rotary shaft 321, the rotary table 32, and the guide plate 322, an integrated structure integrating power transmission, direction locking, and precision indexing is formed. Together with the coordinated action of the push-pull cylinder 36 and the push rod 361, the orderly and reliable connection between the tube expansion, reset, and mold changing processes is realized, greatly improving the stability of equipment operation and the controllability of processing rhythm.

[0070] The tube expanding guide assembly 342 includes a reset guide sleeve 3421 coaxially slidably disposed outside the tube expanding needle 341. A guide reset spring 323 abuts against the reset guide sleeve 3421 and the guide plate 322. A needle guide sleeve 3422 is installed on the outside of the reset guide sleeve 3421, and the outer end of the tube expanding needle 341 always passes through the needle guide sleeve 3422 and is located outside it. A tube limiting sleeve 3423 is installed on the outside of the needle guide sleeve 3422, and an elastic bushing 3424 is installed in the inner cavity of the tube limiting sleeve 3423. The inner diameter of the elastic bushing 3424 increases with the diameter of the tube expanding needle 341. The elastic bushing 3424 is used to elastically abut against its outer wall when the capillary copper tube 4 is expanded to prevent it from deforming and maintain coaxiality.

[0071] The guide return spring 323 between the reset guide sleeve 3421 and the guide plate 322 constitutes the elastic reset core of this component, ensuring that after each tube expansion operation, the entire tube expansion guide assembly 342 can automatically and accurately return to its initial position under the action of spring force, preparing for the next processing cycle and improving the reliability and rhythm consistency of the operation. The needle guide sleeve 3422 installed on the outside of the reset guide sleeve 3421 has the primary function of always wrapping and guiding the outer end of the tube expansion needle 341, ensuring that the tube expansion needle 341 does not drift radially during the operation, and maintaining its strict alignment with the axis of the capillary copper tube 4, which is the basis for achieving uniform tube expansion. The tube limiting sleeve 3423 and the elastic bushing 3424 installed in its inner cavity constitute a dynamic adaptive clamping and protection structure. The inner diameter of the elastic bushing 3424 is designed to increase with the diameter of the tube expanding needle 341 at the corresponding station. This allows it to elastically fit and support the outer wall of the capillary copper tube 4 from the outside when it is expanded by the tube expanding needle 341, providing radial flexible constraint for the capillary copper tube 4. This effectively counteracts the outward expansion cracking tendency generated inside the copper tube during tube expansion, preventing plastic deformation such as instability, wrinkling, or excessive thinning of the tube wall. At the same time, it continuously corrects the workpiece position, ensuring that the capillary copper tube 4 and the tube expanding needle 341 maintain extremely high coaxiality throughout the entire tube expansion deformation process. This directly guarantees the forming quality, dimensional accuracy, and integrity of the tube wall of the expanded section, greatly improving the finished product qualification rate.

[0072] A horizontally sliding tie rod 362 is provided through the expansion pipe fixing plate 31. The tie rod 362 is located on the outer side of the rotary table 32 along its radial direction. One end of the tie rod 362 is connected to the piston rod of the push-pull cylinder 36 through the push-pull mounting plate 363. The other end of the tie rod 362 extends along its axial direction to the outer side of the reset guide sleeve 3421. The tie rod 362 is coaxially arranged with the push-pull cylinder 36. Several push rods 361 are installed on the push-pull mounting plate 363 and are equidistantly arranged along the circumference of the reset guide sleeve 3421.

[0073] One end of the pull rod 362 is fixedly connected to the piston rod of the push-pull cylinder 36 via the push-pull mounting plate 363, and the two are coaxially arranged. This allows the axial pulling force output by the push-pull cylinder 36 to be efficiently and without off-center load transmitted to the pull rod 362 in a straight line, reducing friction loss and energy dispersion, thereby improving power transmission efficiency and motion accuracy, and extending the service life of the push-pull cylinder 36. The other end of the pull rod 362 extends beyond the reset guide sleeve 3421 and is located on its outer side. When the push-pull cylinder 36 retracts, the mechanical traction of the pull rod 362 ensures that the reset guide sleeve 3421 can be reliably and forcibly pulled back to its initial position. This effectively prevents the reset action from being delayed or even failing due to insufficient elasticity, fatigue decay, or increased frictional resistance caused by long-term use of the guide reset spring 323, thus ensuring the timeliness and accuracy of the reset of the expansion tube guide assembly 342 after each working cycle. This rigid active reset protection, together with the elastic reset provided by the guide reset spring 323, constitutes a double reset insurance, which greatly improves the reliability and stability of the equipment during continuous operation and avoids misalignment or equipment interference failures in subsequent pipe expansion processes that may be caused by incomplete reset.

[0074] Meanwhile, several push rods 361 installed on the push-pull mounting plate 363 are equidistantly arranged along the circumference of the reset guide sleeve 3421. When the push-pull cylinder 36 is activated, these push rods 361 can apply force to the reset guide sleeve 3421 synchronously and uniformly from multiple points in the circumference, avoiding uneven load, jamming or local wear caused by single-point force, ensuring the smooth and synchronous movement of the expansion tube guide assembly 342 along the axial direction, and helping to distribute the load and reduce the fatigue stress of key components.

[0075] In this embodiment, a ratchet 325 is provided on the outer peripheral surface of the rotary disk 32, and a pawl 326 elastically abuts against the ratchet 325 is installed on the expansion tube fixing plate 31; the pawl 326 and the ratchet 325 cooperate to limit the rotary disk 32 to rotate unidirectionally around its axis; the outer peripheral surface of the rotary disk 32 abuts against the damping rubber strip 37, one end of the damping rubber strip 37 is fixedly connected to the expansion tube fixing plate 31, and the other end of the damping rubber strip 37 is threadedly connected to the expansion tube fixing plate 31. By turning the nut, the length of the damping rubber strip 37 is changed, so that the abutment pressure between the damping rubber strip 37 and the rotary disk 32 is adjustable.

[0076] The ratchet 325 and pawl 326 constitute a reliable mechanical one-way rotation limiting mechanism. Under the action of the spring, the pawl 326 always presses against the ratchet 325, allowing the rotary table 32 to smoothly rotate one tooth pitch in the working direction (such as clockwise or counterclockwise) to complete indexing under the drive of the rotary cylinder 33, while effectively locking it in the opposite direction. This prevents the rotary table 32 from unexpectedly reversing or shifting after mold changing due to equipment vibration, air supply fluctuations, or the reaction force of the tube expansion process. It ensures the absolute accuracy of the tube expansion pin 341 and the tube insertion channel 221 on the axis at each processing station, providing a crucial guarantee for the stable execution of multi-step sequential tube expansion.

[0077] The damping strip 37 elastically abuts against the outer circumference of the rotary table 32, forming an adjustable buffer and positioning damping structure. Specifically, as the rotary table 32 rapidly rotates and approaches the target position, the damping strip 37 provides gradually increasing resistance through friction, effectively absorbing rotational inertia and allowing the rotary table 32 to decelerate smoothly until it comes to a stop, avoiding the impact, noise, and mechanical wear caused by rigid positioning. Secondly, the adjustable clamping force allows for optimization of the damping effect based on actual working conditions (such as rotational speed and rotational inertia of the rotary table 32), ensuring both rapid indexing action and precise, wobbly stopping position. The rigid unidirectional locking of the ratchet 325 and pawl 326, combined with the adjustable flexible buffering of the damping strip 37, achieves rapid, smooth, precise, and reliable indexing action of the rotary table 32, significantly improving the overall operating quality and lifespan of the equipment.

[0078] The push-pull cylinder 36 is connected to one outlet of the reversing valve 364 through the push-pull air passage; the rotary cylinder 33 is connected to the other outlet of the reversing valve 364 through the rotary air passage; the inlet of the reversing valve 364 is connected to an external high-pressure air source; and a one-way sequence valve 365 is provided on both the push-pull air passage and the rotary air passage.

[0079] When the reversing valve 364 switches, compressed air first overcomes the set pressure of one of the one-way sequence valves 365, driving the corresponding cylinder (e.g., push-pull cylinder 36) to complete its entire stroke. Only after this cylinder has completed its stroke and the pipeline air pressure has further increased will the other one-way sequence valve 365 be opened, thereby driving the next cylinder (e.g., rotary cylinder 33) to begin its operation. This sequential control, forcibly implemented by the one-way sequence valve 365, fundamentally ensures, from a fluid dynamics perspective, that the "push / pull" action of the expansion guide assembly 342 driven by the push-pull cylinder 36 and the "indexing" action of the rotary table 32 driven by the rotary cylinder 33 are executed strictly in the preset sequence. This prevents mechanical interference and collisions that may occur if the two mechanisms move simultaneously due to misoperation or signal interference, greatly improving the safety and timing reliability of equipment operation. Meanwhile, the pressure regulating function of the one-way sequence valve 365 allows for fine adjustment of the action rhythm of each cylinder according to the actual working conditions, ensuring smooth connection and controllable rhythm of the entire tube expansion cycle (including tube expansion, reset, and mold changing), providing core control assurance for achieving stable and efficient automated processing. Preferably, a photoelectric switch one is provided on the outside of the pull rod 362, and a photoelectric switch two for detecting the position of its piston rod is provided on the outside of the rotary cylinder 33. Photoelectric switches one and two are electrically connected to the controller of the tube expansion punch device 3.

[0080] Photoelectric switch one is used to detect the axial displacement limit position of pull rod 362 in real time, thereby accurately determining whether the expansion guide assembly 342 driven by push-pull cylinder 36 has completed the "push" into place or the "pull" back to place. Photoelectric switch two is used to detect the stroke position of piston rod of rotary cylinder 33, directly reflecting whether rotary table 32 has completed one station's intermittent indexing rotation. The position signals collected by the two photoelectric switches are fed back to the controller in real time, enabling the controller to accurately determine the execution status and completion of the two core sub-actions: "expansion guide assembly movement" and "rotary table indexing". Based on this feedback, the controller can precisely control the opening and closing sequence of each valve in the pneumatic circuit, ensuring that push-pull cylinder 36 and rotary cylinder 33 operate strictly according to the safe logic sequence of "action completion, signal confirmation, next step triggering", effectively preventing mechanical interference, mold collision, or workpiece processing errors caused by overtravel, incomplete positioning, or disordered timing. It improves the reliability, safety, and consistency of automated equipment operation and processing, providing important sensing and control guarantees for achieving stable and high-quality automated cyclic operations.

[0081] In this embodiment, the clamping mechanism 22 includes a vertically arranged clamping mounting plate 222. One side of the clamping mounting plate 222 is fixedly connected to the piston rod of the conveying cylinder 21. The clamping mounting plate 222 is horizontally slidably arranged on the frame 1. A pneumatic clamping seat 223 is installed on the other side of the clamping mounting plate 222. A through-tube channel 221 passes through the clamping mounting plate 222, the pneumatic clamping seat 223 and the conveying cylinder 21. The through-tube channel 221 is coaxially arranged with the piston rod of the conveying cylinder 21.

[0082] The clamping mounting plate 222 is constrained to slide on the guide rail of the frame 1, forming a rigid and precisely guided linear motion structure. When the clamping mechanism 22 reciprocates under the drive of the conveying cylinder 21, it maintains extremely high straightness and stability, effectively preventing lateral deviation or jamming, thus providing a foundation for the precise feeding of the capillary copper tube 4. The pneumatic clamping seat 223, installed on the other side of the clamping mounting plate 222, ensures effective transmission of clamping force through its stable connection with the clamping mounting plate 222. The tube-passing channel 221 is designed to pass through the pneumatic clamping seat 223 and the clamping mounting plate 222, extending into the conveying cylinder 21, with its axis strictly coaxial with the piston rod axis of the conveying cylinder 21. This through-type, coaxial channel design ensures that the entire path of the capillary copper tube 4, from insertion and passage to clamping, lies on the same centerline. This not only greatly facilitates the rapid insertion and positioning of workpieces, but also structurally ensures that the axis of the expanded end of the clamped capillary copper tube 4 is automatically aligned with the axis of the expanded pin 341 on the subsequent expanded tube station. This fundamentally eliminates problems such as tube skew and uneven wall thickness caused by clamping eccentricity, providing a crucial prerequisite for obtaining high-quality, high-coaxial tube forming.

[0083] The pneumatic clamping seat 223 includes a seat body 2231. Inside the seat body 2231, a reciprocating piston 2232 is provided. The outer end of the piston 2232 is set as an outwardly expanding cone. Several clamping wedges 2233 adapted to it are installed on the outer end of the piston 2232. The inner sides of the several clamping wedges 2233 together form a tube passage 221. The inner end of the clamping wedges 2233 is set as an inwardly contracting cone. A clamping bushing 2234 adapted to it is installed on the inner side of the clamping wedges 2233. The inner diameter of the clamping bushing 2234 is larger than that of the tube passage 221. The interior of the clamping bushing 2234 is provided with a transition guide slope. The clamping bushing 2234 increases the clamping area of ​​the capillary copper tube 4, reduces the clamping pressure, and prevents the capillary copper tube 4 from being clamped and deformed.

[0084] The pneumatic clamping seat 223 achieves efficient and flexible clamping of the capillary copper tube 4 through its internal conical linkage structure. When compressed air drives the piston 2232 to reciprocate, the conical surface at its outer end interacts with the matching inner conical surfaces of several clamping wedges 2233, converting the axial linear motion of the piston 2232 into the radial synchronous contraction or opening of the clamping wedges 2233, thereby clamping and releasing the capillary copper tube 4 passing through its central tube passage 221. This force transmission method based on the inclined plane principle can amplify the small axial thrust of the cylinder into a large radial clamping force, ensuring the firmness of the clamping. Moreover, the clamping bushing 2234 installed inside the clamping wedges 2233 has an inner diameter slightly larger than the tube passage 221 and is provided with a transition guide inclined surface. This design allows the capillary copper tube 4 to be smoothly guided during insertion. In the clamped state, the flexible clamping bushing 2234 can wrap around the outer wall of the capillary copper tube 4, significantly increasing the actual contact area. This disperses the concentrated force into uniform surface pressure, effectively reducing the clamping pressure per unit area. This overcomes the problem that the capillary copper tube 4, due to its soft material, is easily crushed or permanently deformed in traditional rigid clamping. While ensuring sufficient clamping force to prevent the capillary copper tube 4 from shifting during the expansion process, it perfectly protects the roundness and surface quality of the capillary copper tube 4, laying the foundation for subsequent high-precision expansion.

[0085] A counterweight mechanism 5 is provided between the clamping mounting plate 222 and the frame 1. The counterweight mechanism 5 includes a counterweight frame 51 vertically mounted on the frame 1. Two reversing wheels 52 are rotatably mounted on the counterweight frame 51, and a counterweight chain 53 is mounted on the two reversing wheels 52. One end of the counterweight chain 53 passes over one of the reversing wheels 52 and connects to the top of the clamping mounting plate 222, and the other end of the counterweight chain 53 passes over the other reversing wheel 52 and connects to the counterweight box 54. The counterweight frame 51 can rotate around the vertical axis and rotates with the clamping mounting plate 222 when it moves, without affecting the movement of the clamping mounting plate 222. The counterweight mechanism 5 is used to lift the clamping mounting plate 222 and prevent it from affecting the accuracy of the axial movement of the capillary copper tube 4 due to its own weight.

[0086] The counterweight mechanism 5 improves the motion accuracy and stability of the clamping mounting plate 222 and its supported pneumatic clamping seat 223 during axial movement through mechanical balance. One end of the counterweight chain 53 is connected to the top of the clamping mounting plate 222, and the other end passes over two reversing wheels 52 and connects to the counterweight box 54. Utilizing the gravity of the counterweight box 54, a continuous and stable vertical lifting force is generated on the clamping mounting plate 222 through the transmission of the counterweight chain 53 and the reversing wheels 52, thereby effectively balancing the self-weight of the clamping mounting plate 222, the pneumatic clamping seat 223, and related components. This reduces the static friction and motion resistance that the conveying cylinder 21 needs to overcome when driving the clamping mounting plate 222 to slide along the frame 1, making its reciprocating motion lighter and smoother, and eliminating the phenomenon of guide rail clearance changes or motion lag caused by self-weight. The counterweight frame 51 is designed to rotate around a vertical axis, allowing the entire counterweight mechanism 5 to adaptively adjust its orientation as the clamping mounting plate 222 moves horizontally. This ensures that the tension direction of the counterweight chain 53 remains vertical, preventing any lateral force that could hinder the horizontal movement of the clamping mounting plate 222. Therefore, this ensures highly precise and consistent axial feeding and retraction of the capillary copper tube 4 in the clamped state, fundamentally preventing potential axial displacement of the capillary copper tube 4 due to the weight of the moving parts, and guaranteeing the positioning accuracy and processing quality of the tube expansion process.

[0087] In this embodiment, during use, the operator passes the capillary copper tube 4 through the center hole of the piston rod of the conveying cylinder 21 and the tube-penetrating channel 221 of the clamping mechanism 22, so that its end protrudes; after starting the tube expander, the rotary cylinder 33 drives the rotary shaft 321 through the one-way clutch 324, which drives the rotary disk 32 and the guide disk 322 to rotate, so that the first (smallest diameter) tube expander needle 341 is coaxially aligned with the tube-penetrating channel 221; subsequently, the piston 2232 of the pneumatic clamping seat 223 pushes the clamping wedge 2233 to retract, and through The capillary copper tube 4 is flexibly clamped by the clamping bushing 2234; then, the push-pull cylinder 36 pushes the tube expansion guide assembly 342 at the current station forward through the push-pull mounting plate 363, the pull rod 362, and the circumferentially equidistant push rods 361, wherein the reset guide sleeve 3421 compresses the guide reset spring 323, the needle guide sleeve 3422 guides the tube expansion needle 341, and the elastic bushing 3424 in the tube limiting sleeve 3423 is ready to support the workpiece; then, the conveying cylinder 21 drives the clamping mounting plate 222 and the clamped tube... The capillary copper tube 4 is fed along the guide rail of the frame 1 towards the tube expanding punch device 3. The counterweight mechanism 5 balances its own weight with the counterweight chain 53 and the counterweight box 54 to ensure smooth movement. The end of the capillary copper tube 4 is inserted into the tube expanding needle 341 under the guidance of the tube expanding guide assembly 342 to complete one tube expansion. After that, the conveying cylinder 21 retracts, and the push-pull cylinder 36 forcibly pulls the tube expanding guide assembly 342 to reset through the pull rod 362. The guide reset spring 323 assists in its accurate return to position. After that, the reversing valve 364 switches the air path, and the one-way sequence valve... Under the control of 365, the rotary cylinder 33 operates, driving the rotary table 32 to overcome the buffer of the damping rubber strip 37 and rely on the unidirectional positioning of the ratchet 325 and the pawl 326 to rotate through one station, so that the next larger diameter tube expander 341 is aligned with the working position; repeat the above tube expansion cycle, and the capillary copper tube 4 passes through all nine tube expander 341 in sequence to complete the progressive tube expansion; finally, the rotary table 32 rotates the feed tube 35 to the working position, the pneumatic clamp 223 is released, and the processed capillary copper tube 4 is taken out through the feed tube 35.

[0088] Example 2

[0089] This embodiment discloses a pneumatic capillary copper tube expansion method, applied to the pneumatic capillary copper tube expander in the above embodiment; the expansion method includes the following steps:

[0090] S1. Pass the capillary copper tube 4 through the tube passage 221 and extend it out of the clamping mechanism 22;

[0091] S2. The rotary cylinder 33 drives the rotary table 32 to rotate, so that the first tube expanding mechanism 34 located downstream of the feeding tube 35 corresponds to the position of the capillary copper tube 4, and the capillary copper tube 4 moves along its axial direction to abut the tube expanding needle 341 of the current tube expanding mechanism 34.

[0092] S3, Clamping mechanism 22 clamps and fixes capillary copper tube 4;

[0093] S4, the push-pull cylinder 36 drives the corresponding tube expansion guide assembly 342 to move along its axis toward the clamping mechanism 22 and abut against it;

[0094] S5. The conveying cylinder 21 drives the clamping mechanism 22 to continuously apply pressure to the tube expansion guide assembly 342, causing the tube expansion guide assembly 342 to move in the opposite direction along its axial direction, while simultaneously driving the capillary copper tube 4 to move together. The capillary copper tube 4 is inserted by the tube expansion needle 341 to complete the tube expansion.

[0095] S6. The conveying cylinder 21 drives the capillary copper tube 4 back to the initial position through the clamping mechanism 22, and the push-pull cylinder 36 drives the tube expansion guide assembly 342 back to the initial position.

[0096] S7. Rotary cylinder 33 drives rotary table 32 to rotate, so that the next tube expansion mechanism 34 corresponds to the position of capillary copper tube 4.

[0097] S8. Repeat S4 to S7 until the capillary copper tube 4 passes through all the tube expanding mechanisms 34 in sequence to complete the tube expansion.

[0098] S9. The rotary cylinder 33 drives the rotary table 32 to rotate, so that the feeding pipe 35 corresponds to the position of the expanded capillary copper tube 4. The clamping mechanism 22 releases the capillary copper tube 4, and the capillary copper tube 4 is moved out of the feeding pipe 35.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pneumatic capillary copper tube expander comprising a frame; characterized in that, The rack is provided with horizontally arranged clamping and conveying device and tube expanding die device; The clamping and conveying device comprises horizontally arranged conveying cylinder, the piston rod of which is provided with clamping mechanism, which is arranged close to the tube expanding die device, the inside of the clamping mechanism is provided with pipe penetrating channel, the clamping mechanism is used for clamping and fixing the expanding end of capillary copper pipe which extends through the pipe penetrating channel; The clamping mechanism comprises vertically arranged clamping mounting plate, the other side of which is provided with pneumatic clamping seat, the inside of the seat body is provided with reciprocating piston, the outer end of the piston is arranged as outwardly expanding cone; the outer end of the piston is provided with several clamping wedge blocks which are matched with the piston, the inside of the clamping wedge blocks jointly surrounds the pipe penetrating channel; the inner end of the clamping wedge block is arranged as inwardly shrinking cone, the inside of the clamping wedge block is provided with clamping bushing which is matched with the clamping wedge block, the inner diameter of the clamping bushing is larger than the pipe penetrating channel, the inside of the clamping bushing is provided with transition guide slope; The tube expanding die device comprises tube expanding fixing plate, the one side of which is rotatably provided with rotary disc which is arranged close to the clamping mechanism, the rotary disc is vertically arranged and connected with rotary cylinder which drives the intermittent rotation of the rotary disc, the rotary disc is horizontally provided with several tube expanding mechanisms and at least one blanking pipe, the several tube expanding mechanisms and the blanking pipe are arranged in the same circle and are spaced apart, the blanking pipe or one of the tube expanding mechanisms which are located at the top of the rotary disc is coaxially arranged with the pipe penetrating channel; The tube expanding mechanism comprises tube expanding needle which is fixedly arranged on the rotary disc; along the rotation direction of the rotary disc, the diameter of the tube expanding needle which is located downstream of the blanking pipe gradually increases; the outside of the tube expanding needle is coaxially and slidably provided with tube expanding guide assembly, the other side of the tube expanding fixing plate is provided with push-pull cylinder which is used for driving the reciprocating movement of the tube expanding guide assembly along the axial direction thereof; The rotary disc is fixedly connected with guide disc through rotary shaft, the tube expanding guide assembly penetrates the guide disc and abuts against guide reset spring between the tube expanding guide assembly and the guide disc; the tube expanding guide assembly comprises reset guide sleeve which is coaxially and slidably arranged outside the tube expanding needle, the guide reset spring abuts against between the reset guide sleeve and the guide disc; the outside of the reset guide sleeve is provided with needle guide sleeve, the outer end of the tube expanding needle always penetrates the needle guide sleeve and is located outside the needle guide sleeve; the outside of the needle guide sleeve is provided with pipe limiting sleeve, the inner cavity of the pipe limiting sleeve is provided with elastic bushing; the inner diameter of the elastic bushing increases with the increase of the diameter of the tube expanding needle.

2. The gas dynamic capillary copper tube expander of claim 1 wherein, The piston rod of the push-pull cylinder is provided with several push rods which are arranged towards the tube expanding guide assembly, the push rods are used for abutting against corresponding tube expanding guide assemblies; The guide disc is coaxially arranged with the rotary disc, the other end of the rotary shaft is connected with the rotary cylinder through one-way clutch.

3. The gas dynamic capillary copper tube expander of claim 2 wherein, The pull rod is horizontally slidably arranged on the pipe expanding fixing plate, is located at the outer side of the rotary disc along the radial direction of the rotary disc, and is connected with the piston rod of the push-pull air cylinder through a push-pull mounting plate. One end of the pull rod extends to the outer side of the reset guide sleeve along the axial direction of the pull rod. The pull rod is coaxially arranged with the push-pull air cylinder. A plurality of push rods are mounted on the push-pull mounting plate, and the plurality of push rods are equidistantly arranged along the circumference of the reset guide sleeve.

4. The gas dynamic capillary copper tube expander of claim 1 wherein, A ratchet is arranged on the outer circumferential surface of the rotary disc, and an elastic pawl is mounted on the pipe expanding fixing plate and abuts against the ratchet. The pawl and the ratchet cooperatively limit the rotary disc to rotate in one direction along the axis of the rotary disc. The outer circumferential surface of the rotary disc abuts against a damping rubber strip. One end of the damping rubber strip is fixedly connected with the pipe expanding fixing plate, and the other end of the damping rubber strip is threadedly connected with the pipe expanding fixing plate. The abutting pressure between the damping rubber strip and the rotary disc is adjustable.

5. The gas dynamic capillary copper tube expander of claim 1 wherein, The push-pull air cylinder is in communication with one air outlet end of a reversing valve through a push-pull air path. The rotary air cylinder is in communication with the other air outlet end of the reversing valve through a rotary air path. The air inlet end of the reversing valve is in communication with an external high-pressure air source. A one-way sequence valve is arranged on the push-pull air path and the rotary air path.

6. The gas dynamic capillary copper tube expander of claim 1 wherein, One side of the clamping mounting plate is fixedly connected with the piston rod of the conveying air cylinder, and the clamping mounting plate is horizontally slidably arranged on the rack. The pipe penetrating channel penetrates the clamping mounting plate, the pneumatic clamping seat and the conveying air cylinder. The pipe penetrating channel is coaxially arranged with the piston rod of the conveying air cylinder.

7. The gas dynamic capillary copper tube expander of claim 1 wherein, A counterweight mechanism is arranged between the clamping mounting plate and the rack. The counterweight mechanism comprises a counterweight frame vertically mounted on the rack, two reversing wheels rotatably mounted on the counterweight frame, and a counterweight chain mounted on the two reversing wheels. One end of the counterweight chain passes around one of the reversing wheels and is connected with the top of the clamping mounting plate, and the other end of the counterweight chain passes around the other reversing wheel and is connected with a counterweight box.

8. A method of expanding a copper tube by gas capillarity, characterized by, The application of the pneumatic capillary copper pipe expanding machine according to any one of claims 1 to 7; the pipe expanding method comprises the following steps: S1, the capillary copper pipe is penetrated through the pipe penetrating channel and extends out of the clamping mechanism; S2, the rotary air cylinder drives the rotary disc to rotate, so that the first pipe expanding mechanism located downstream of the blanking pipe corresponds to the position of the capillary copper pipe. The capillary copper pipe moves along the axial direction and abuts against the pipe expanding needle of the current pipe expanding mechanism; S3, the clamping mechanism clamps and fixes the capillary copper pipe; S4, the push-pull air cylinder drives the corresponding pipe expanding guide assembly to move along the axial direction and abut against the clamping mechanism; S5, the conveying air cylinder drives the clamping mechanism to continuously press the pipe expanding guide assembly, so that the pipe expanding guide assembly moves in the reverse direction along the axial direction, and the capillary copper pipe moves together. The capillary copper pipe is inserted into the pipe expanding needle to complete the pipe expansion; S6, the conveying air cylinder drives the capillary copper pipe to return to the initial position through the clamping mechanism, and the push-pull air cylinder drives the pipe expanding guide assembly to return to the initial position; S7, the rotary air cylinder drives the rotary disc to rotate, so that the next pipe expanding mechanism corresponds to the position of the capillary copper pipe; S8, repeat S4 to S7 until the capillary copper pipe sequentially passes through all the pipe expanding mechanisms to complete the pipe expansion. S9, the rotary cylinder drives the rotary disc to rotate, so that the blanking tube corresponds to the position of the expanded capillary copper tube, the clamping mechanism releases the capillary copper tube, and the capillary copper tube is moved out by the blanking tube.

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