A turning processing device for polytetrafluoroethylene pipe fittings

Abstract

The present invention discloses a turning processing device for polytetrafluoroethylene pipe fittings. Aiming at the problem that when turning thin-walled pipe fittings made of polytetrafluoroethylene materials on existing lathes, due to the excessive elasticity of the materials, the materials will move together with the cutting tool during cutting, resulting in the phenomenon of "tool deflection", and ultimately leading to insufficient cutting. The present invention can be directly installed on the lathe guide rail instead of the apron of an ordinary machine tool. The device includes: a lathe guide rail mechanism, a first-level lead screw assembly, and a second-level lead screw assembly. The lathe guide rail mechanism includes a rotating base, and the second-level lead screw assembly includes two special cutting tools. The rotating base is used to control the cutting angle of the cutting tool, the first-level lead screw assembly is used to control the overall movement of the two cutting tools, and the second-level lead screw assembly controls the relative movement between the cutting tools. The present invention can efficiently process high-precision polytetrafluoroethylene pipe fittings, meeting the requirements for precision fluoroplastic pipe fittings in the semiconductor manufacturing field.

Description

Technical Field

[0001] The present invention relates to a turning device in the field of machining, and more particularly to a turning device for polytetrafluoroethylene pipe fittings. Background Art

[0002] In the field of semiconductor manufacturing, polytetrafluoroethylene (PTFE) is often used as a material. Pipe fittings made of this material are heat-resistant and corrosion-resistant, and can transport ultra-clean strong acids, ultrapure water, etc. without introducing impurities. For example, in the immersion system of modern lithography equipment, a large number of air bag pumps with PTFE bellows as the core parts are used.

[0003] However, high-precision pipe fittings have long been difficult to machine, such as polytetrafluoroethylene pipe fittings. Although polytetrafluoroethylene belongs to thermoplastic plastics, generally speaking, pipe fittings made of thermoplastic plastics can be manufactured by the blow molding method. However, polytetrafluoroethylene is different from other thermoplastic plastics. It has a relatively high melting point, and the liquid obtained after melting has a relatively high viscosity, showing a "jelly-like" state and being not easy to flow. Therefore, it cannot be blow molded. At the same time, polytetrafluoroethylene has very good elasticity and is not easy to directly roll into high-precision thin-walled pipes like metals.

[0004] In traditional turning methods for polytetrafluoroethylene pipe fittings, usually only one tool is used to cut the pipe fittings. This will cause the surface of the pipe fittings to always be subjected to cutting force on one side, resulting in not only low efficiency but also uneven stress on the pipe fittings during the cutting process. During the turning process of thin-walled pipe fittings, uneven stress will cause the pipe fittings to undergo elastic movement along the movement direction of the cutting tool, that is, the "tool deflection" phenomenon, and ultimately lead to insufficient cutting. The "tool deflection" phenomenon will cause a significant decrease in the surface quality of the finally machined pipe fittings, and at the same time, the dimensional accuracy will also deviate from the expected value. For example, if the inner wall of the pipe is machined first and then the outer wall, when turning the outer wall, the material will elastically deform inward, resulting in insufficient cutting amount, and finally the actual wall thickness of the obtained pipe fittings is thicker than the drawing; similarly, if the outer wall of the pipe is machined first and then the inner wall, similar problems will inevitably occur.

[0005] For the "tool deflection problem" during the turning process, the existing solution is to manually increase the cutting amount to offset the cutting deficiency caused by "tool deflection". However, modifying the cutting amount requires a lot of processing experience, and once the grade of polytetrafluoroethylene is changed or the basic parameters of the pipe fittings are modified, such as diameter, wall thickness, etc., the cutting amount needs to be redesigned, which is time-consuming and laborious. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a mechanical processing device that uses two turning tools to simultaneously cut the inner and outer walls of a pipe fitting. Such a structure can cause the inner and outer surfaces of the material to be subjected to cutting force at the same time, so that the material is subjected to uniform force and is less likely to suffer from the problem of "letting go of the tool", thereby improving the processing quality.

[0007] The technical solution of the present invention is as follows:

[0008] The present invention comprises a lathe guide rail mechanism, a primary screw assembly and a secondary screw assembly; a primary screw assembly is installed on the lathe guide rail mechanism, the primary screw assembly can rotate on the lathe guide rail mechanism, a secondary screw assembly is installed on the primary screw assembly, the primary screw assembly is driven to adjust the position of the secondary screw assembly on the primary screw assembly; the secondary screw assembly is driven to turn a polytetrafluoroethylene pipe fitting.

[0009] The lathe guide rail mechanism comprises a guide rail body, a rotating base, a lathe lead screw assembly and a lathe optical bar group; the guide rail body is mounted with a rotating base, a lathe lead screw assembly and a lathe optical bar group are installed on one side of the guide rail body, the lathe lead screw assembly and the lathe optical bar group are both mounted in the rotating base, and the cooperation between the lathe lead screw assembly and the lathe optical bar group enables the rotating base to slide on the guide rail body; a first-level lead screw assembly is installed on the upper surface of the rotating base, and the first-level lead screw assembly can rotate on the rotating base.

[0010] A load-bearing turntable is arranged in the middle of the upper surface of the rotating base, and a first-stage screw assembly is installed on the load-bearing turntable. An arc-shaped turning track is provided on the upper surface of the rotating base outside the load-bearing turntable, and a plurality of pin holes arranged at intervals along the circumference are provided in the arc-shaped turning track. The first-stage screw assembly rotates around the load-bearing turntable.

[0011] The primary screw assembly comprises a primary screw base, a primary screw guide rail, a co-directional screw, a primary screw end frame, a primary screw drive motor and a counterweight;

[0012] The lower surface of the first-level screw base is connected to the lathe guide rail mechanism, a counterweight is installed on one side of the upper surface of the first-level screw base, a first-level screw guide is installed on the other side of the upper surface of the first-level screw base, and a co-directional screw is also installed on the other side of the upper surface of the first-level screw base through a first-level screw end frame. The first-level screw guide is parallel to the co-directional screw and arranged at intervals. A secondary screw assembly is sleeved in the first-level screw guide, and the bottom surface of the secondary screw assembly is slidably connected to the first-level screw guide, and the output shaft of the first-level screw driving motor is coaxially connected to the co-directional screw; the first-level screw driving motor drives the co-directional screw to rotate, so that the secondary screw assembly sleeved in the co-directional screw slides along the first-level screw guide.

[0013] A plurality of pin fixing holes penetrating vertically are provided in a primary screw base between the co-directional screw and the counterweight, and the plurality of pin fixing holes are symmetrically arranged at both ends of the co-directional screw.

[0014] The secondary lead screw assembly includes a secondary lead screw base, a coolant pipe support, a coolant pipe, a special turning tool set, secondary lead screw end frames, a secondary lead screw intermediate support, a secondary smooth rod, a secondary lead screw drive motor, a bidirectional lead screw, and rolling bearings;

[0015] The secondary lead screw base is mounted on the primary lead screw assembly and slides on the primary lead screw assembly. The two ends of the bidirectional lead screw are respectively mounted on the secondary lead screw base through corresponding secondary lead screw end frames. The middle part of the bidirectional lead screw is connected to the secondary lead screw base through the secondary lead screw intermediate support and rolling bearings. The secondary lead screw drive motor is fixedly mounted on the secondary lead screw end frame, and the output shaft of the secondary lead screw drive motor is coaxially and fixedly connected to the bidirectional lead screw. Corresponding special turning tool sets are respectively sleeved on both sides of the bidirectional lead screw. A coolant pipe support is also arranged between the two special turning tool sets. The coolant pipe is fixedly mounted on the coolant pipe support. At least one secondary smooth rod is also arranged between the two secondary lead screw end frames. One end of the secondary smooth rod is fixedly mounted in one secondary lead screw end frame. The other end of the secondary smooth rod sequentially passes through a special turning tool set, the coolant pipe support, and the other special turning tool set and is then fixedly mounted in the other secondary lead screw end frame. The cutting edges of the two special turning tool sets both face inwards. The wall of the polytetrafluoroethylene pipe fitting is arranged between the cutting edges of the two special turning tool sets. The cutting edges of the two special turning tool sets respectively machine the inner and outer tube walls of the polytetrafluoroethylene pipe fitting.

[0016] The special turning tool set includes a turning tool mounting seat, a cutting edge, a tool shank, and a reinforcing rib;

[0017] The turning tool mounting seat is sleeved on one side of the bidirectional lead screw and the secondary smooth rod. One side of the turning tool mounting seat is connected to one end of the tool shank. The other end of the tool shank is connected to the cutting edge. The turning tool mounting seat and the tool shank are also strengthened and connected through the reinforcing rib.

[0018] The special turning tool set is composed of two special turning tools in a mirror-symmetrical manner, with the tool tips completely opposite to each other, and is mounted at both ends of the bidirectional lead screw. In this way, during the actual cutting process, the cutting forces received by the material cancel each other out, reducing the occurrence of the "tool deflection" problem. Since the polytetrafluoroethylene material is relatively soft and the cutting force generated during the cutting process is very low, the requirement for the stiffness of the tool is relatively low. Since the thread pitches of the two sections of the bidirectional lead screw are different, when the bidirectional lead screw rotates, the two turning tools will move closer to or away from each other. The turning tool is provided with a coolant positioning hole, which can be connected to the coolant pipe support to achieve the synchronization of the positions of the automatic cooling pipe and the turning tool.

[0019] The present invention controls the overall movement of two turning tools through a first-level lead screw assembly. Rotating the co-rotating lead screw can make the two special turning tools move together without changing the relative distance between the turning tools. During the actual machining process, if the middle radius of the pipe to be machined (i.e., ) remains unchanged all the time, then during the machining process, there is no need for the first-level lead screw assembly to move, and the first-level lead screw assembly can be kept in a self-locking state. Otherwise, the first-level lead screw assembly needs to cooperate and continuously follow the shape change of the pipe.

[0020] The present invention controls the relative spacing between two turning tools through a second-level lead screw assembly. Rotating the bi-directional lead screw can make the two turning tools approach or move away from each other, thereby realizing the feed and retraction movements during the cutting process. By using bi-directional lead screws with different leads, the two turning tools can be made to feed and retract at different speeds.

[0021] More deeply, a set of inertial coordinate systems can be established. Suppose the co-rotating lead screw of the first-level lead screw assembly can drive the second-level lead screw assembly to move left and right as a whole at a speed of, and the bi-directional lead screw can make the two turning tools a and b move relative to the second-level lead screw assembly at speeds of and respectively. Then the actual movement speeds of the two turning tools relative to the workpiece are + and - respectively. Therefore, by reasonably designing the leads of the co-rotating lead screw and the bi-directional lead screw, a large difference in the feed speeds of the two turning tools can be achieved. In actual use, this characteristic of the device can be utilized to simultaneously perform precision turning of the inner surface of the pipe fitting and rough turning of the outer surface of the pipe. Even when and are selected to be the same, a machining form can be realized in which one turning tool does not move and the other turning tool performs cutting alone.

[0022] Experiments show that improving the surface accuracy of pipe fittings can significantly extend the service life of pipe fittings and avoid the premature occurrence of liquid leakage problems. The present invention simultaneously cuts the inner and outer walls of polytetrafluoroethylene plastic with two turning tools to cancel out the cutting forces with each other, thereby reducing the adverse effects of the "tool deflection" phenomenon on the turning processing of polytetrafluoroethylene materials and effectively improving the turning processing accuracy of polytetrafluoroethylene plastic pipe fittings.

[0023] The beneficial effects of the present invention are as follows:

[0024] The present invention simultaneously cuts the inner and outer walls of polytetrafluoroethylene plastic with two turning tools, so that the forces on the inner and outer walls are uniform and the radial cutting forces cancel each other out. It can significantly improve the dimensional accuracy and surface accuracy of polytetrafluoroethylene pipe fittings, thereby reducing the production and manufacturing costs of high-precision polytetrafluoroethylene pipe fittings and meeting the usage requirements for a large number of high-precision polytetrafluoroethylene plastic pipe fittings in the semiconductor equipment industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 is a schematic diagram of the rotating base structure of the present invention;

[0027] Figure 3 It is a structural schematic diagram of a primary screw assembly of the present invention;

[0028] Figure 4 It is a schematic diagram of the overall installation of the secondary screw assembly of the present invention;

[0029] Figure 5 It is a schematic diagram of the installation of the secondary lead screw and the special turning tool of the present invention;

[0030] Figure 6 are cross-sectional views of three typical pipe fittings of the present invention;

[0031] Figure 7 Two processing methods corresponding to the present invention and a working principle diagram for ordinary thin-walled pipe fittings;

[0032] Figure 8 The rough drawing and working principle diagram of the processing of the annular structure pipe fitting of the present invention;

[0033] Figure 9 The rough drawing and working principle diagram of processing the corrugated thin-walled pipe fitting of the present invention;

[0034] Figure 10 It is the surface condition of corrugated thin-walled pipes under traditional processing methods;

[0035] Figure 11 The surface condition of the corrugated thin-walled pipe obtained by processing using the device of the present invention;

[0036] In the figure: 1. Lathe guide rail mechanism; 101. Lathe lead screw assembly; 102. Lathe light rod assembly; 2. Rotating base; 201. Load-bearing turntable; 202. Arc turn rail; 3. Primary lead screw assembly; 3011. Primary lead screw guide rail; 3012. Co-directional lead screw; 3013. Primary lead screw end bracket; 3014. Primary lead screw drive motor; 302. Counterweight; 3031. Pin fixing hole; 3032. Turn rail groove; 4. Secondary lead screw assembly; 4011. Coolant pipe bracket; 4012. Special Use turning tool set; 40121, cutting edge; 40122, tool rod; 40123, reinforcing rib; 40124, coolant positioning hole; 40125, turning tool smooth rod hole; 40126, turning tool lead screw hole; 4021, secondary lead screw end bracket; 4022, secondary lead screw intermediate bracket; 4023, secondary smooth rod; 4024, secondary lead screw drive motor; 4025, bidirectional lead screw; 40251, worm gear; 40252, rolling bearing; 4031, thread groove; 4032, guide groove. DETAILED DESCRIPTION

[0037] The present invention / utility model is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0038] As shown Figure 1 in the figure, the present invention includes a guide rail mechanism 1 of a common lathe, a first-level lead screw assembly 3 and a second-level lead screw assembly 4; the first-level lead screw assembly 3 is installed on the guide rail mechanism 1 of the common lathe, the first-level lead screw assembly 3 can rotate on the guide rail mechanism 1 of the common lathe, the second-level lead screw assembly 4 is installed on the first-level lead screw assembly 3, and driven by the first-level lead screw assembly 3, the position of the second-level lead screw assembly 4 on the first-level lead screw assembly 3 is adjusted to control the overall movement of two turning tools, so as to realize the machining of special-shaped pipe fittings with a changing radius; driven by the second-level lead screw assembly 4, the polytetrafluoroethylene pipe fittings are turned.

[0039] As shown Figure 2 in the figure, the guide rail mechanism 1 of the common lathe includes a guide rail body, a rotating base 2, a lathe lead screw assembly 101 and a lathe optical bar group 102; the rotating base 2 is sleeved in the guide rail body, the lathe lead screw assembly 101 and the lathe optical bar group 102 are installed on one side surface of the guide rail body, the lathe lead screw assembly 101 and the lathe optical bar group 102 are both sleeved in the rotating base 2, and the cooperation of the lathe lead screw assembly 101 and the lathe optical bar group 102 enables the rotating base 2 to slide on the guide rail body. Among them, the lathe lead screw assembly 101 includes a lathe drive motor and a lathe lead screw, the lathe drive motor is installed on one side surface of the guide rail body, one end of the lathe lead screw is coaxially connected with the output shaft of the lathe drive motor, the other end of the lathe lead screw is installed on one side surface of the guide rail body, and the lathe lead screw is sleeved in the rotating base 2; the lathe optical bar group 102 includes at least one optical bar, both ends of the optical bar are fixedly installed on one side surface of the guide rail body, and the optical bar is sleeved in the rotating base 2; the first-level lead screw assembly 3 is installed on the upper surface of the rotating base 2, and the first-level lead screw assembly 3 can rotate on the rotating base 2.

[0040] A load-bearing turntable 201 is arranged in the middle of the upper surface of the rotating base 2, the first-level lead screw assembly 3 is installed on the load-bearing turntable 201, an arc-shaped track 202 is opened on the upper surface of the rotating base 2 outside the load-bearing turntable 201, and a plurality of pin holes arranged at equal intervals along the circumference are opened in the arc-shaped track 202. In a specific implementation, the adjacent pin holes on the arc-shaped track are spaced 5°. The first-level lead screw assembly 3 rotates around the load-bearing turntable 201, and the pin fixing hole 3031 and the pin hole of the arc-shaped track 202 are connected by a pin to realize the limit of the first-level lead screw assembly 3 and the fixation of the first-level lead screw assembly at a specific angle, so as to control the movement of the special turning tool along the guide rail direction and the orientation angle of the turning tool.

[0041] As shown Figure 3As shown in the figure, the first-level lead screw assembly 3 includes a first-level lead screw base, a first-level lead screw guide rail 3011, a co-directional lead screw 3012, a first-level lead screw end frame 3013, a track conversion groove 3032, a first-level lead screw drive motor 3014, and a counterweight 302; the lower surface of the first-level lead screw base is connected to the lathe guide rail mechanism 1, and a counterweight 302 is installed on one side of the upper surface of the first-level lead screw base, which can make the overall cutting process more stable and reduce vibration. A first-level lead screw guide rail 3011 is installed on the other side of the upper surface of the first-level lead screw base, and the first-level lead screw guide rail (3011) is used to ensure the precise and stable sliding of the second-level lead screw assembly. A co-directional lead screw 3012 is also installed on the other side of the upper surface of the first-level lead screw base through a first-level lead screw end frame 3013. The co-directional lead screw adopts a high-precision ball screw and is controlled by a high-precision stepping motor to ensure the precise and reliable movement of the whole. A plurality of pin fixing holes 3031 penetrating up and down are provided in the first-level lead screw base between the co-directional lead screw 3012 and the counterweight 302, and the plurality of pin fixing holes 3031 are symmetrically arranged at both ends of the co-directional lead screw 3012. A polytetrafluoroethylene pipe fitting is arranged on one side of the first-level lead screw base close to the first-level lead screw guide rail 3011 and the co-directional lead screw 3012. The first-level lead screw guide rail 3011 and the co-directional lead screw 3012 are arranged in parallel and at intervals. In the initial state, the axes of the first-level lead screw guide rail 3011 and the co-directional lead screw 3012 are perpendicular to the axes of the lathe lead screw and the optical rod. A second-level lead screw base of the second-level lead screw assembly 4 is sleeved in the first-level lead screw guide rail 3011, and the guide rail groove 4032 on the bottom surface of the second-level lead screw assembly 4 is slidably connected to the first-level lead screw guide rail 3011. The output shaft of the first-level lead screw drive motor 3014 passes through the first-level lead screw end frame 3013 at one end and then is coaxially connected to one end of the co-directional lead screw 3012; the first-level lead screw drive motor 3014 drives the co-directional lead screw 3012 to rotate, so that the second-level lead screw assembly 4 sleeved in the co-directional lead screw 3012 slides along the first-level lead screw guide rail 3011.

[0042] As Figure 4As shown in the figure, the secondary lead screw assembly 4 includes a secondary lead screw base, a coolant pipe support 4011, a coolant pipe, a special turning tool set 4012, a secondary lead screw end frame 4021, a secondary lead screw intermediate support 4022, a secondary smooth rod 4023, a secondary lead screw drive motor 4024, a bidirectional lead screw 4025, a worm gear 40251 and a rolling bearing 40252; the secondary lead screw base is installed on the primary lead screw assembly 3 and the secondary lead screw base slides on the primary lead screw assembly 3. Specifically, a threaded groove 4031 is formed in the secondary lead screw base, and the same-direction lead screw 3012 is installed in the threaded groove 4031 of the secondary lead screw base. A guide rail groove 4032 is formed in the bottom surface of the secondary lead screw base, and the primary lead screw guide rail 3011 is embedded in the guide rail groove 4032, and the secondary lead screw base slides along the primary lead screw guide rail 3011. Both ends of the bidirectional lead screw 4025 are respectively installed on the secondary lead screw base through the corresponding secondary lead screw end frames 4021, and the bidirectional lead screw is composed of two threads with opposite helix directions; in addition, the secondary lead screw end frame 4021 adopts a detachable design, which is convenient for replacing bidirectional lead screws with different lead pitches and special turning tools. The middle part of the bidirectional lead screw 4025 is connected to the secondary lead screw base through the secondary lead screw intermediate support 4022 and the rolling bearing 40252. The middle part of the bidirectional lead screw 4025 is coaxially connected to the inner ring of the rolling bearing 40252, and the outer ring of the rolling bearing 40252 is installed in the secondary lead screw intermediate support 4022. The same-direction lead screw 3012 has the same axial direction as the bidirectional lead screw 4025. The secondary lead screw drive motor 4024 is fixedly installed on the secondary lead screw end frame 4021, and the output shaft of the secondary lead screw drive motor 4024 is coaxially and fixedly connected to one end of the bidirectional lead screw 4025 through the worm gear 40251, where the worm gear 40251 is used for the decelerated rotation of the bidirectional lead screw; corresponding special turning tool sets 4012 are respectively sleeved on both sides of the bidirectional lead screw 4025, and a coolant pipe support 4011 is further arranged between the two special turning tool sets 4012. A coolant pipe is fixedly installed on the coolant pipe support 4011. At least one secondary smooth rod 4023 is further arranged between the two secondary lead screw end frames 4021. One end of the secondary smooth rod 4023 is fixedly installed in one secondary lead screw end frame 4021, and the other end of the secondary smooth rod 4023 sequentially passes through a special turning tool set 4012, the coolant pipe support 4011 and the other special turning tool set 4012 and is then fixedly installed in the other secondary lead screw end frame 4021. The bidirectional lead screw 4025 and the secondary smooth rod 4023 are arranged in parallel and at intervals; the cutting tool directions of the two special turning tool sets 4012 both face inwards, that is, the cutting tools of the two special turning tool sets 4012 are arranged oppositely, and the pipe wall of the polytetrafluoroethylene pipe fitting is arranged between the cutting tools of the two special turning tool sets 4012, and the cutting tools of the two special turning tool sets 4012 respectively turn the inner and outer pipe walls of the polytetrafluoroethylene pipe fitting.When cutting PTFE pipe fittings, the two-way lead screw drives two turning tools to move towards the outer wall and the inner wall of the blank pipe fitting respectively, so as to realize the simultaneous cutting of the inner and outer walls of the tubular blank, offset the cutting force received by the blank during the processing, and avoid the problem that when using a traditional single turning tool for processing, the highly elastic PTFE will undergo elastic deformation in the direction away from the turning tool when receiving a unilateral cutting force, ultimately resulting in a reduction in processing accuracy.

[0043] As Figure 5 shown, the special turning tool set 4012 includes a turning tool mounting seat, a cutting edge 40121, a tool shank 40122 and a reinforcing rib 40123; the turning tool mounting seat is sleeved on one side of the two-way lead screw 4025 and the secondary optical bar 4023. A turning tool lead screw hole 40126 and a turning tool optical bar hole 40125 are provided in the turning tool mounting seat. The two-way lead screw 4025 is installed in the turning tool lead screw hole 40126 of the turning tool mounting seat, and the secondary optical bar 4023 is installed in the turning tool optical bar hole 40125 of the turning tool mounting seat. A coolant positioning hole 40124 is provided on the upper surface of the turning tool mounting seat, and the coolant pipe bracket 4011 is fixedly installed on the upper surface of the turning tool mounting seat through the cooperation of fasteners with the coolant positioning hole 40124; one side of the turning tool mounting seat is connected to one end of the tool shank 40122, and the other end of the tool shank 40122 is connected to the cutting edge 40121. The turning tool mounting seat and the tool shank 40122 are also strengthened and connected through the reinforcing rib 40123.

[0044] Since the actual required cutting force of the PTFE material is very small, the requirement for the stiffness of the turning tool is very low. In actual use, for a turning tool shank 40122 with a common diameter, on the premise of additionally designing the reinforcing rib 40123, when the overhanging length L1 of the tool shank reaches 40 cm, the overhanging length L2 of the cutting edge 40121 can be designed to be about 35 mm, and neither will affect the processing quality.

[0045] The working principle of the present invention is to rotate the two-way lead screw to simultaneously cut the inner and outer walls of the PTFE plastic pipe blank with two turning tools, realize the mutual cancellation of the cutting force, and further reduce the adverse effect of the "tool deflection" phenomenon on the turning processing of the PTFE material, effectively improving the turning processing accuracy of the PTFE plastic pipe fitting. In addition, rotating the co-directional lead screw can make the two special turning tools move together without changing the relative distance between the turning tools. During the actual processing, if the middle radius of the pipe fitting to be processed (i.e.:) remains unchanged all the time, then during the processing, there is no need for the first-level lead screw assembly to move, and the first-level lead screw assembly can be kept in a self-locking state. Otherwise, the first-level lead screw assembly needs to cooperate and continuously follow the shape change of the pipe.

[0046] Figure 6The cross-sectional views of three typical pipe fittings that can be processed by the present invention are shown. It should be noted that the three typical pipe fittings are only a part of the embodiments of the present invention, rather than all embodiments. For those of ordinary skill in the art, without creative efforts, other thin-walled pipe fittings with different diameters, lengths, and dimensions can be processed using this device. Among them Figure 6 In (a) is an ordinary thin-walled pipe fitting, Figure 6 In (b) is a thin-walled pipe fitting with a changing diameter and a circular ring bulge, Figure 6 In (c) is a corrugated thin-walled pipe fitting.

[0047] The present invention can provide two main cutting methods. Taking the processing of ordinary thin-walled pipe fittings as an example, as Figure 7 :

[0048] The first is the "layer-by-layer cutting method", which means cutting the wall thickness of the blank pipe fitting layer by layer until the thickness reaches the requirements of the drawing. Applied to this device, it is as shown in (a) of Figure 7 Specific operations are as follows: First, adjust the bidirectional lead screw to shorten the relative distance between the two turning tools. Then, drive the rotating base to continuously move axially along the lathe guide rail through the lathe lead screw to achieve the cutting of the first layer. After the first layer of cutting is completed, shorten the relative distance between the two turning tools and re-control the rotating base to perform axial movement to achieve layer-by-layer cutting. Repeat this cycle until the cutting is completed.

[0049] The second is the "one-cut method", which means cutting the wall of the blank pipe fitting in a pure radial direction, directly cutting the position to be cut to the thickness required by the drawing, and then axially moving the tool to continue cutting the next part. Applied to this device, it is as shown in (b) of Figure 7 Specific operations are as follows: First, determine the position of the rotating base on the guide rail and fix the rotating guide rail. Then, continuously rotate the bidirectional lead screw until the wall of the blank is cut to the required wall thickness. Then, reverse-rotate the bidirectional lead screw to retract the tool. After the retraction is completed, control the rotating base to move about the thickness of one cutting edge, and then repeat the above movement until the entire pipe fitting is completely cut.

[0050] The "layer-by-layer cutting method" is characterized by a continuous cutting process, no connection problems between the cutting parts, high cutting efficiency, and a smoother surface. However, the "layer-by-layer cutting method" cannot completely offset the cutting force in the axial direction. This method is suitable for processing ordinary thin-walled pipe fittings with a relatively flat surface and no or insignificant radius changes, such as (a) of Figure 6 ; but it is not suitable for those like Figure 6Pipe fitting processing with large radius changes in (c) and prone to axial movement. For the "one-cut method", since the surface of the pipe fitting obtained by this method is composed of the connection of multiple cutting results, the overall surface is not smooth enough. However, during each cutting process, the turning tool has no axial movement, which can completely offset the cutting force. This method is suitable for fittings like Figure 6 in (c) with large radius changes and prone to axial movement, but when processing fittings like Figure 6 in (a), its efficiency and surface quality are inferior to the "layer-by-layer cutting method".

[0051] For fittings like Figure 6 in (b), its dimensional characteristics are that there are uniform annular structures distributed on the pipe, and in addition, the radius of the upper half of the pipe fitting remains unchanged, while the radius of the lower half shrinks at an angle of 10°. The processing process for this pipe fitting is as follows:

[0052] First, determine whether the size of the special turning tool meets the processing requirements. It should be ensured that the maximum variation amounts S1 and S2 of the outer and inner radii of the pipe fitting in (b) like Figure 6 are both less than Figure 5 the overhang length L2 of the cutting edge of the turning tool in

[0053] to avoid contact friction between the tool shank and the workpiece during the turning feed process, which affects the processing quality. Figure 6 Secondly, preprocess the pipe-shaped blank. When using the present invention, to ensure that the cutting force can be fully offset, it should be ensured that the actual cutting amounts of the two turning tools are approximately equal as much as possible. Therefore, it is necessary to preprocess the blank. For fittings like Figure 8 in (b), the relatively reasonable shape of the preprocessed blank should be as shown in

[0054] Finally, process the blank. For fittings like Figure 6 in (b), the complexity of its structure is between Figure 6 in (a) and Figure 6For the pipe fittings between (c), either the "layer-by-layer cutting method" or the "one-cut method" can be used. Here, the "one-cut method" is taken as an example: First, process the part where the radius shrinks. Adjust the pin fit between the rotating base and the first-level lead screw so that the cutter bar is inclined at an angle of 10°. Then, perform cutting using the "one-cut method". Among them, due to the change in the middle radius, each axial feed needs to be advanced at an angle of 10°. Therefore, during each machining process, it is necessary to control the movement of the rotating base and the co-directional lead screw simultaneously. After the cutting of the part where the radius shrinks is completed, then cut the part where the radius does not change. At this time, the co-directional lead screw does not need to move, and it is only necessary to maintain the self-locking of the co-directional lead screw and not move.

[0055] For Figure 6 the processing of the corrugated thin-walled pipe fittings of (c), its structure is the most complex, but the overall process is very close to that of the pipe fittings in Figure 6 (b).

[0056] First, determine whether the size of the special turning tool meets the processing requirements. It should be ensured that Figure 6 the maximum changes in the outer and inner radii S1 and S2 of the pipe fittings in (c) are both less than Figure 5 the overhang length L2 of the cutting edge of the turning tool in, so as to avoid contact friction between the cutter bar and the workpiece during the turning feed process, which affects the processing quality.

[0057] Secondly, preprocess the blank. To ensure that the cutting amounts of the two turning tools are approximately equivalent, the preprocessed shape is designed as shown in Figure 9 (a).

[0058] Finally, process the blank. Due to the structural characteristics of this type of pipe fitting, there are a large number of length mutations in the radius along the axial direction, so it is not suitable to use the "layer-by-layer cutting method" for processing. At the same time, due to the change in the radius, a co-directional lead screw is required for coordinated movement. The specific processing flow is as shown in Figure 9 (b). First, rotate the double lead screw, and the two turning tools approach each other to realize the cutting of the blank. After this cutting is completed, retract the tool, control the rotating base to move forward to the next cutting position, and then rotate the co-directional lead screw system to ensure that the pipe wall is always in the middle position between the two turning tools. Finally, rotate the double lead screw to make the two turning tools approach each other to complete the next cutting, and continuously repeat the above process until the cutting is completed.

[0059] Figure 10 and Figure 11The surfaces of the corrugated thin-walled pipe fittings obtained by using the traditional turning process and the device of the present invention respectively are shown in two photos, both of which are taken by a high-precision optical camera under the same experimental conditions. It can be seen by comparison that the surface of the pipe fittings obtained by the traditional processing method is rough, with a large number of irregular cutting marks remaining, while the surface of the corrugated pipe processed by using the device of the present invention is bright, translucent, has a good reflective effect, and basically no processing defects can be seen. Obviously, the actual effect of the device of the present invention is remarkable.

[0060] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A turning processing device for polytetrafluoroethylene pipe fittings, characterized in that, It includes a lathe guide rail mechanism (1), a first-level lead screw assembly (3), and a second-level lead screw assembly (4); The first-level lead screw assembly (3) is installed on the lathe guide rail mechanism (1). The first-level lead screw assembly (3) can rotate on the lathe guide rail mechanism (1). The second-level lead screw assembly (4) is installed on the first-level lead screw assembly (3). Driven by the first-level lead screw assembly (3), the position of the second-level lead screw assembly (4) on the first-level lead screw assembly (3) is adjusted; driven by the second-level lead screw assembly (4), the polytetrafluoroethylene pipe fittings are turned; The lathe guide rail mechanism (1) includes a guide rail body, a rotating base (2), a lathe lead screw assembly (101), and a lathe optical bar group (102); The rotating base (2) is sleeved in the guide rail body. The lathe lead screw assembly (101) and the lathe optical bar group (102) are installed on one side surface of the guide rail body. The lathe lead screw assembly (101) and the lathe optical bar group (102) are both sleeved in the rotating base (2). The cooperation of the lathe lead screw assembly (101) and the lathe optical bar group (102) enables the rotating base (2) to slide on the guide rail body. The first-level lead screw assembly (3) is installed on the upper surface of the rotating base (2). The first-level lead screw assembly (3) can rotate on the rotating base (2); The second-level lead screw assembly (4) includes a second-level lead screw base, a coolant pipe support (4011), a coolant pipe, a special turning tool group (4012), a second-level lead screw end frame (4021), a second-level lead screw intermediate support (4022), a second optical bar (4023), a second-level lead screw drive motor (4024), a bidirectional lead screw (4025), and a rolling bearing (40252); The secondary lead screw base is installed on the primary lead screw assembly (3) and slides on the primary lead screw assembly (3). Both ends of the bi-directional lead screw (4025) are respectively installed on the secondary lead screw base through corresponding secondary lead screw end brackets (4021). The middle part of the bi-directional lead screw (4025) is connected to the secondary lead screw base through a secondary lead screw intermediate bracket (4022) and a rolling bearing (40252). The secondary lead screw drive motor (4024) is fixedly installed on the secondary lead screw end bracket (4021), and the output shaft of the secondary lead screw drive motor (4024) is coaxially and fixedly connected to the bi-directional lead screw (4025). Corresponding special turning tool sets (4012) are respectively sleeved on both sides of the bi-directional lead screw (4025). A coolant pipe bracket (4011) is also arranged between the two special turning tool sets (4012). A coolant pipe is fixedly installed on the coolant pipe bracket (4011). At least one secondary optical bar (4023) is also arranged between the two secondary lead screw end brackets (4021). One end of the secondary optical bar (4023) is fixedly installed in one secondary lead screw end bracket (4021), and the other end of the secondary optical bar (4023) sequentially passes through a special turning tool set (4012), the coolant pipe bracket (4011), and the other special turning tool set (4012) and is then fixedly installed in the other secondary lead screw end bracket (4021). The cutting tool directions of the two special turning tool sets (4012) both face inwards. The pipe wall of the polytetrafluoroethylene pipe fitting is arranged between the cutting tools of the two special turning tool sets (4012), and the cutting tools of the two special turning tool sets (4012) respectively turn the inner and outer pipe walls of the polytetrafluoroethylene pipe fitting. The processed polytetrafluoroethylene pipe fitting includes a common thin-walled pipe fitting, and the pipe is distributed with uniformly annular-structured thin-walled pipe fittings or corrugated thin-walled pipe fittings.

2. The turning processing device for a polytetrafluoroethylene pipe fitting according to claim 1, characterized in that, In the middle of the upper surface of the rotating base (2), a load-bearing rotating platform (201) is arranged. The primary lead screw assembly (3) is installed on the load-bearing rotating platform (201). An arc-shaped rotating track (202) is formed on the upper surface of the rotating base (2) outside the load-bearing rotating platform (201). A plurality of pin holes are arranged at intervals along the circumference in the arc-shaped rotating track (202). The primary lead screw assembly (3) rotates around the load-bearing rotating platform (201) as the center.

3. The turning processing device for a polytetrafluoroethylene pipe fitting according to claim 1, characterized in that, The primary lead screw assembly (3) includes a primary lead screw base, a primary lead screw guide rail (3011), a co-directional lead screw (3012), a primary lead screw end bracket (3013), a primary lead screw drive motor (3014), and a counterweight (302). The lower surface of the first-level lead screw base is connected to the lathe guide mechanism (1). On one side of the upper surface of the first-level lead screw base, a counterweight (302) is installed. On the other side of the upper surface of the first-level lead screw base, a first-level lead screw guide rail (3011) is installed. On the other side of the upper surface of the first-level lead screw base, a co-directional lead screw (3012) is also installed through a first-level lead screw end frame (3013). The first-level lead screw guide rail (3011) and the co-directional lead screw (3012) are arranged in parallel and at intervals. A second-level lead screw assembly (4) is sleeved in the first-level lead screw guide rail (3011). The bottom surface of the second-level lead screw assembly (4) is slidably connected to the first-level lead screw guide rail (3011). The output shaft of the first-level lead screw driving motor (3014) is coaxially connected to the co-directional lead screw (3012). The first-level lead screw driving motor (3014) drives the co-directional lead screw (3012) to rotate, so that the second-level lead screw assembly (4) sleeved in the co-directional lead screw (3012) slides along the first-level lead screw guide rail (3011).

4. The turning processing device for a polytetrafluoroethylene pipe fitting according to claim 3, wherein, A plurality of pin fixing holes (3031) penetrating up and down are formed in the first-level lead screw base between the co-directional lead screw (3012) and the counterweight (302). The plurality of pin fixing holes (3031) are symmetrically arranged at both ends of the co-directional lead screw (3012).

5. The turning processing device for a polytetrafluoroethylene pipe fitting according to claim 1, characterized in that The special turning tool set (4012) includes a turning tool mounting seat, a cutting edge (40121), a tool shank (40122) and a reinforcing rib (40123). The turning tool mounting seat is sleeved on one side of the bi-directional lead screw (4025) and the second-level optical bar (4023). One side of the turning tool mounting seat is connected to one end of the tool shank (40122). The other end of the tool shank (40122) is connected to the cutting edge (40121). The turning tool mounting seat and the tool shank (40122) are also strengthened and connected through a reinforcing rib (40123).

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