Coating spray gun

Abstract

The utility model belongs to the field of spraying equipment, and particularly relates to a coating spray gun. An existing paint spray gun cannot independently adjust the air flow of an air channel in a gun needle, and the discharging atomization form cannot be changed through the air flow. According to the paint spray gun, the air flow in the gun needle is independently adjusted, and the discharging atomization form of the spray nozzle is changed. The gun body is connected to the bottom of the storage tank, the piston is arranged in the gun body and moves, the gun needle is provided with a gun needle air channel, the front end of the gun body is provided with a nozzle with a spraying hole, the middle section of the gun body is provided with a material cavity communicated with the storage tank, the rear end of the gun body is provided with a piston cavity matched with the piston, and the gun needle penetrates through the piston cavity in a sealed mode and extends into the material cavity. A spring is arranged in the piston cavity to abut against the piston so that the gun needle tends to move forwards to block the nozzle, the gun body is provided with a pipe base with one air inlet channel and two air outlet channels, the air channels comprise an air inlet channel, a first air channel for air outlet and a second air channel for air outlet, the first air channel and the second air channel are communicated with the piston cavity and the gun needle air channel respectively, and the pipe base is provided with an adjusting switch to change the air conveying flow of the second air channel.

Description

Technical Field

[0001] The utility model relates to the field of spraying equipment, in particular to a paint spray gun. Background Art

[0002] A paint spray gun is a common spraying tool in the construction painting industry. It uses compressed air to drive the paint to spray out of the nozzle at high speed to quickly cover the building surface. Compared with the paint on a traditional roller brush, the spraying speed is fast and the efficiency is high. A common paint spray gun has an integrated structure of a storage tank and a spray gun. The storage tank is used to hold the paint, and the spray gun is connected to a compressed air source. With the help of compressed air, the paint is sprayed out and forms various different dispersion effects. The needle of the spray gun has an air passage inside, and the air passage communicates with a piston chamber at the rear of the spray gun. The piston in the piston chamber is fixedly connected to the needle to achieve linkage. The movement of the needle can adjust the opening and closing of the nozzle and the size of the opening. There is also a spring inside the spray gun to push the piston forward, so that the needle can close the nozzle. During operation, the external air source supplies air to the piston chamber. After the air pressure in the piston chamber increases, the piston can be pushed backward, overcoming the spring force and moving backward. The needle moves synchronously with the piston to open the nozzle. To ensure that the piston can be pushed, there is a minimum requirement for the supply air pressure. If the air pressure is too small, the piston cannot be pushed backward. Since the internal air supply of the needle comes from the compressed gas supplied to the piston chamber, when the cross-sectional area of the air passage inside the needle remains unchanged, the air flow rate is proportional to the air pressure and is fixed, which cannot meet the spraying requirements of fine atomization. Summary of the Utility Model

[0003] The technical problem to be solved and the technical task proposed by the utility model is to overcome the technical problem that the paint spray gun with an integrated structure of a storage tank and a spray gun in the prior art cannot independently adjust the air flow rate of the air passage inside the needle and cannot meet the spraying requirements of different refinement degrees. The utility model provides a paint spray gun that can independently adjust the air flow rate inside the needle, and then change the atomization form of the nozzle discharge through the air flow rate to meet the production requirements of fine spraying.

[0004] Technical solution adopted by the present utility model to solve technical problems: A paint spray gun includes a gun body connected to the bottom of a storage tank, and a piston and a needle that move synchronously inside it. A nozzle with a spray hole is provided at the front end of the gun body, a material chamber communicating with the storage tank is provided in the middle section of the gun body, a piston chamber matching the piston is provided at the rear end of the gun body, the needle passes through the piston chamber in a sealed manner and extends into the material chamber. A spring is provided in the piston chamber to press against the piston to make the needle move forward to block the nozzle. A needle air passage is provided inside the needle, and the needle air passage extends to the front end face of the needle to form a blowing hole. The needle can move with the piston to change the gap with the spray hole. The feature is that a pipe seat is provided on the gun body, and an air supply passage with one inlet and two outlets is provided inside the pipe seat. The air supply passage includes an air inlet passage and a first air passage and a second air passage communicating with it. An opening is provided on the pipe seat to communicate with the air inlet passage, the first air passage communicates with the piston chamber, the second air passage communicates with the needle air passage, and an adjustment switch for changing the air supply flow rate of the second air passage is provided on the pipe seat. The present utility model adds a pipe seat on the gun body of the paint spray gun, and an air supply passage with one inlet and two outlets is provided inside it. By controlling one of the air supply passages, the air supply flow rate of the needle air passage is adjusted, and the atomization form of the material discharged from the nozzle is changed to meet different fine spraying requirements. During operation, the adjustment switch is manipulated to change the air supply flow rate of the second air passage. Since the second air passage is communicated with the needle air passage, the air supply flow rate in the needle air passage and the atomization form of the material discharged from the nozzle also change accordingly. The air supply of the first air passage and the second air passage both come from the air inlet passage, and the air inlet passage is externally connected to the air supply through the opening on the pipe seat.

[0005] As a further improvement and supplement to the above technical solution, the present utility model adopts the following technical measures: An installation hole passage is provided between the material chamber and the piston chamber. The axis of the installation hole passage coincides with that of the piston chamber. The needle passes through the installation hole passage and extends into the material chamber. Guide air holes are provided on the surface of the needle to communicate with the needle air passage. The middle section of the installation hole passage is in clearance fit with the needle, and radial hole passages are provided on the inner wall of the installation hole passage corresponding to the middle section. The inner and outer ends of the hole passage communicate with the clearance and the second air passage respectively. The installation hole passages on both sides of the middle section are in sealed fit with the needle. During the movement of the needle, the guide air holes keep the clearance formed between the middle section of the installation hole passage and the needle in communication. During the reciprocating movement of the needle, the second air passage is communicated with the clearance formed between the needle and the installation hole passage through the radial hole passage on the inner wall of the middle section of the installation hole passage. At the same time, this clearance is also kept in communication with the guide air holes on the surface of the needle that communicate with the needle air passage. Then the second air passage can be communicated with the needle air passage to realize air supply. When air is supplied, the parts on both sides of the middle section of the installation hole passage are still in sealed fit with the needle to prevent air leakage.

[0006] A clearance fit is formed between the middle section of the installation hole passage and the needle through a groove. The groove is an arc-shaped groove extending in the circumferential direction or a continuous annular groove in the circumferential direction, and the length of the projection of the groove along the radial direction of the installation hole passage matches the stroke of the needle movement. A clearance for ventilation is formed between the middle section of the installation hole passage and the needle through an arc-shaped groove extending around the circumference or a continuous annular groove. At the same time, the width of the groove along the length dimension of the projection in the radial direction of the installation hole passage also matches the stroke of the needle moving back and forth. When the needle moves back and forth, the air guide holes on the surface are kept in communication with the annular groove.

[0007] The groove is arranged on the surface of the needle or the inner wall of the installation hole passage, or grooves are arranged on both the surface of the needle and the inner wall of the installation hole passage. The groove can be located on the surface of the needle, or on the inner wall of the installation hole passage, or grooves are arranged on both the surface of the needle and the inner wall of the installation hole passage.

[0008] The installation hole passage is the lumen of a sleeve. The sleeve is hermetically sleeved in a transition cavity arranged in the gun body. The sleeve, the transition cavity and the needle are coaxial. The two ends of the transition cavity communicate with the piston cavity and the material cavity respectively. The needle passes through the sleeve. The two ends of the sleeve are hermetically connected to the inserted needle through sealing rings. A first radial hole passage penetrating the side wall of the sleeve is arranged on the inner wall of the lumen of the sleeve. The two ends of the first radial hole passage extend and expand around the circumference on the inner wall of the lumen of the sleeve and the outer wall surface of the sleeve to form an arc-shaped groove or an annular groove. The air guide hole communicates with the arc-shaped groove or the annular groove on the inner wall of the lumen. The second air passage communicates with the arc-shaped groove or the annular groove on the outer wall surface of the sleeve. The installation hole passage is formed in the lumen of a sleeve. The sleeve can be mass-produced independently and assembled with the gun body to improve production efficiency. During assembly, the sleeve is positioned in the gun body by hermetically sleeving it with a transition cavity whose two ends communicate with the piston cavity and the material cavity respectively in the gun body. The axes of the sleeve, the transition cavity and the needle coincide. The needle passes through the sleeve and can move normally. The two ends of the sleeve are hermetically connected to the inserted needle through sealing rings to prevent air leakage. A first radial hole passage is arranged on the inner wall of the lumen of the sleeve to penetrate the side wall of the sleeve. The inner and outer ends of the first radial hole passage extend and expand on the inner wall of the lumen and the outer wall of the sleeve to form an arc-shaped groove or an annular groove. As long as the air guide hole and the second air passage can communicate with the corresponding arc-shaped grooves or annular grooves on the inner and outer wall surfaces of the sleeve, the air guide hole can communicate with the second air passage. Among them, the arc-shaped groove or the annular groove extending on the inner wall of the lumen is used to form a clearance fit between the installation hole passage and the needle.

[0009] The tube seat is perpendicular to the gun body and is an integral structure with it, the air inlet and the second air channel are respectively a large-diameter channel and a small-diameter channel coaxially connected, and a ring surface is formed at the connection point, and one end of the large-diameter channel away from the ring surface extends to the outer end surface of the tube seat to form a mounting hole, and the regulating switch is an regulating rod that seals and penetrates into the large-diameter channel from the mounting hole, and the diameter of the rod section of the regulating rod inserted into the large-diameter channel is smaller than the inner diameter of the large-diameter channel. The regulating rod can change the spacing between the inner end of the rod and the ring surface by moving in and out of the large-diameter channel to adjust the air flow rate of the large-diameter channel input into the small-diameter channel; one end of the small-diameter channel away from the ring surface extends to the inner wall surface of the transition cavity to form an opening; the inner wall of the large-diameter channel is provided with an opening and extends along a direction parallel to the axis of the gun body to form a first air channel connected to the piston cavity, and one end of the first air channel away from the large-diameter channel extends to the inner wall of the piston cavity to form an opening; the side wall of the tube seat has a hole at a position outside the gun body to connect to the air inlet. During operation, the adjusting rod is operated to make the inner end of the rod move away from or close to the annular surface, so as to adjust the amount of gas entering the small-diameter channel from the large-diameter channel. When the inner end of the rod completely blocks the inner hole in the middle of the annular surface, the gas flow rate is zero. Since the diameter of the rod section of the adjusting rod that penetrates the large-diameter channel is smaller than the inner diameter of the channel, in the process of the adjusting rod moving in and out of the large-diameter channel, the gas in the large-diameter channel can be smoothly delivered into the piston cavity through the first air channel to push the piston to move backward. The through hole opened on the side wall of the tube seat on the outer side of the gun body is used to connect the gas source to deliver gas into the air inlet channel.

[0010] The adjusting rod is inserted through a tailstock and threadedly connected thereto. The tailstock is provided with a mounting portion which is sleeved in the mounting hole and is fastened to the tube seat. The adjusting rod includes a thin rod section at the front section and a threaded section at the rear section. The diameter of the thin rod section is smaller than the diameter of the threaded section, and the diameter of the threaded section is smaller than the inner diameter of the large diameter channel. The adjusting rod is inserted through a tailstock and installed on the tube seat. The tailstock is fastened by sleeve connection with the mounting portion and the mounting hole and fixed to the tube seat. The fastening of the tailstock and the tube seat can be threaded connection or plug-in or other existing technology fixation. The thin rod section of the adjusting rod passes through the tailstock and extends into the large diameter channel. The threaded section of the adjusting rod is inserted through the tailstock and threadedly connected thereto. When working, the adjusting rod is rotated forward and backward to change the length of the adjusting rod entering and exiting the large diameter channel, and the air flow rate of the air inlet corresponding to the large diameter channel into the second airway corresponding to the small diameter channel also changes accordingly.

[0011] The annular surface is a plane; or the annular surface and the inner end of the regulating rod are both in the shape of a cone, and the taper of the annular surface is greater than the taper of the inner end of the rod. The annular surface and the inner end of the regulating rod are both in the shape of a cone, and the tapers of the two are different, and the function is to adjust the amount of air sent from the air inlet to the second airway; the annular surface can also be a plane, and the inner end of the regulating rod is a cone or other shape that can match the annular surface, and the two can match to adjust the amount of air in the second airway.

[0012] A positioning device for limiting the rearward movement stroke of the piston is provided at the rear end of the gun body. The positioning device includes a tail cap and a screw rod passing through it. The screw rod is threadedly connected to the tail cap. A cylindrical cavity with an open end facing backward is provided at the rear end of the gun body. The tail cap is fixedly connected to the cylindrical cavity to cover the open end, and together with the cylindrical cavity, it forms the piston cavity. The two ends of the spring respectively abut against the piston and the tail cap. The screw rod limits the piston by abutting against the rearward moving piston. By rotating the screw rod to adjust the length of the part screwed into the cylindrical cavity, the rearward movement stroke of the piston can be limited. Consequently, the rearward movement position of the gun needle and the discharge amount of the nozzle are locked accordingly. The longer the part of the screw rod screwed into the cylindrical cavity, the shorter the rearward movement stroke of the piston.

[0013] A locking member is sleeved on the rod section of the screw rod extending out of the piston cavity, and the locking member is threadedly connected to the screw rod. During the use of the paint spray gun, the piston will frequently move backward under the drive of the input gas and impact the screw rod, causing the screw rod to loosen and deviate from its original set position. The rearward movement strokes of the piston and the gun needle will gradually increase. Tighten the locking member so that it abuts against and presses the tail cap to lock the screw rod to the tail cap, preventing the pre-adjusted screw rod from being loosened and displaced due to the collision with the piston.

[0014] The utility model realizes the adjustment of the gas flow rate of the gun needle airway through a pipe seat with an internal one-in-two-out gas transmission passage and a regulating switch. One of the inlets in the gas transmission passage is the air inlet for connecting the external air source, and the two outlets are respectively the first airway connecting to the piston cavity and the second airway connecting to the gun needle airway. During operation, the regulating switch is operated to control the gas flow rate of the second airway, thereby controlling the gas flow rate of the gun needle airway and changing the atomization form of the nozzle discharge to meet different fine spraying requirements. Further, a positioning device with a locking member is also provided at the rear end of the gun body to lock the adjusted screw rod, preventing the screw rod from being loosened and displaced due to the collision with the frequently rearward moving piston, and thus avoiding the situation that the rearward movement limits of the piston and the gun needle do not reach the preset effect. Description of the Drawings

[0015] Figure 1 : The three-dimensional view of the utility model.

[0016] Figure 2 : The side view of the utility model.

[0017] Figure 3 : Figure 2 The sectional view taken along the A-A direction of

[0018] Figure 4 : Figure 3 The enlarged view of part B of

[0019] In the figure: 1. Storage tank, 1-1. Material chamber, 2. Gun body, 3. Piston, 4. Gun needle, 4-1. Gun needle airway, 4-2. Blowing hole, 4-3. Air guide hole, 5. Nozzle, 5-1. Spray hole, 6. Piston chamber, 7. Spring, 8. Pipe seat, 8-1. Mounting hole, 9. Inlet duct, 10. First air duct, 11. Second air duct, 12. Adjustment switch, 12-1. Thin rod section, 12-2. Threaded section, 12-3. Cone end, 13. Mounting hole, 14. Groove, 15. Sleeve, 16. Transition cavity, 17. Sealing ring, 18. First radial channel, 19. Annular surface, 20. Tail stock, 20-1. Mounting part, 21. Tail cap, 22. Screw, 23. Locking piece, 24. Switch spring, 25. Outer ring groove, 26. Air pipe, 27. Handle, 27-1. Handle cavity, 28. Air inlet connector, 29. Trigger rod, 30. Valve stem, 30-1. Plug, 31. Air outlet chamber, 32. Air inlet chamber, 33. Variable diameter chamber, 34. Cross bar, 35. Top plate. DETAILED DESCRIPTION

[0020] The utility model is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0021] like Figures 1 to 4 As shown, this embodiment is a paint spray gun, including a gun body 2 connected to the bottom of a material storage tank 1 and a piston 3 and a gun needle 4 arranged therein and moving synchronously, a nozzle 5 with a spray hole 5-1 is arranged at the front end of the gun body 2, a material chamber 1-1 connected to the material storage tank 1 is arranged in the middle section of the gun body 2, a piston chamber 6 matched with the piston 3 is arranged at the rear end of the gun body 2, the gun needle 4 seals and passes through the piston chamber 6 to extend into the material chamber 1-1, a spring 7 is arranged in the piston chamber 6 to press against the piston 3 so that the gun needle 4 tends to move forward to block the nozzle, a gun needle airway 4-1 is arranged in the gun needle 4, and the gun needle airway 4-1 extends to the front end surface of the gun needle 4 to form a blowing hole 4-2, the gun needle 4 can change the gap with the spray hole 5-1 with the movement of the piston 3, a tube seat 8 is provided on the gun body 2, and a gas transmission passage with one inlet and two outlets is provided in the tube seat 8, and the gas transmission passage includes an air inlet 9 and two air outlets connected thereto, and the two air outlets are respectively a first air passage 10 and a second air passage 11. An opening is provided on the tube seat 8 to communicate with the air inlet 9, the first air passage 10 communicates with the piston chamber 6, and the second air passage 11 communicates with the gun needle air passage 4-1. The tube seat 8 is provided with an adjusting switch 12 which can change the air transmission flow of the second air passage 11, and the air inlet 9 is connected to an external air supply through the opening on the tube seat 8.

[0022] When in use, the regulating switch is operated to change the gas flow rate of the second gas channel. Since the second gas channel is connected to the gun needle gas channel, the gas flow rate in the gun needle gas channel and the atomization form of the nozzle discharge material will be adjusted and changed with the change of the gas flow rate. This embodiment can adjust and change the gas flow rate in the gun needle alone, and then use the change of the gas flow rate to change the atomization form of the nozzle discharge material, so as to meet the production needs of fine spraying.

[0023] On the side of the storage tank 1, there is also a hollow tubular handle 27 for holding. An air source control switch assembly is provided on the handle 27 to control the supply of air to the pipe seat 8, such as Figure 3 As shown, the air source control switch assembly includes a vertically arranged trigger rod 29, a valve rod 30, and a switch spring 24. The trigger rod 29 is inserted into the handle cavity 27-1. The upper end of the trigger rod 29 extends out of the handle 27. The upper section of the valve rod 30 is inserted into the handle cavity 27-1 and abuts against the lower end of the trigger rod 29 upward. The lower section of the valve rod 30 is inserted into a hollow air inlet joint 28 fixed to the bottom of the handle 27. The valve rod 30 is sealed by a rubber ring at the position where it passes through the air inlet joint 28. The inner cavity of the air inlet joint 28 is divided into an air outlet chamber 31, a reduced-diameter chamber 33, and an air inlet chamber 32 from top to bottom. The air inlet joint 28 is opened at the position corresponding to the side of the air outlet chamber 31 to communicate with the air outlet chamber and is connected to an air delivery pipe 26. The other end of the air delivery pipe 26 is connected to an opening on the pipe seat 8 to communicate with the air inlet passage 9. The lower end of the valve rod 30 forms a plug 30-1 located in the air inlet chamber 32. The bottom of the air inlet joint 28 is opened to connect a gas pipe to input compressed air from an air compressor. One end of the switch spring 24 is sleeved on the valve rod 30, and the other end abuts against the inner cavity wall of the air inlet joint 28. Under normal conditions, the switch spring acts to move the valve rod upward, and the plug 30-1 blocks the interface on the side of the reduced-diameter chamber 33 communicating with the air inlet chamber 32. At this time, the air inlet joint 28 cannot supply air to the pipe seat, and the paint spray gun is in a state of interrupted air supply. When pressing the trigger rod 29 by hand to push the valve rod 30, the valve rod 30 elastically moves downward against the force of the switch spring 24. At this time, the switch spring 24 is compressed, and the plug 30-1 disengages from the originally blocked interface, and the internal air path of the air inlet joint 28 is unblocked. At this time, the air inlet joint 28 can supply air to the pipe seat. After releasing the hand, the switch spring 24 elongates and resets, pushing the valve rod and the trigger rod 29 back to their original positions, and the plug 30-1 returns to its original position to block the interface again, and the paint spray gun returns to the original state of interrupted air supply. There is also a positioning structure on the handle 27 that can lock the position of the trigger rod to keep it elevated or depressed. In addition, there is a protruding crossbar on the extended end of the trigger rod, and a top plate is fixed on the handle. When rotating the trigger rod, making the crossbar abut against the top plate upward or downward can lock the current position of the trigger rod, keeping the trigger rod elevated or depressed for convenient construction. Among them, keeping the trigger rod elevated can maintain the disconnection of the internal air path of the air inlet joint, and keeping the trigger rod depressed can maintain the unblocked internal air path of the air inlet joint.

[0024] Furthermore, an installation passage 13 is provided between the material chamber 1-1 and the piston chamber 6. The axes of the installation passage 13, the piston chamber 6, and the syringe needle 4 coincide. The syringe needle 4 passes through the installation passage 13 and extends into the material chamber 1-1. An air guide hole 4-3 is provided on the surface of the syringe needle 4 to communicate with the syringe needle air passage 4-1. The middle section of the installation passage 13 and the syringe needle 4 are in clearance fit, and a radial passage is provided on the inner wall of the installation passage 13 corresponding to the middle section. The inner and outer ends of the passage communicate with the clearance and the second air passage 11 respectively. The installation passage 13 on both sides of the middle section and the syringe needle 4 are in sealed fit. During the movement of the syringe needle 4, the air guide hole 4-3 always remains in communication with the clearance formed between the middle section of the installation passage 13 and the syringe needle 4. When the syringe needle moves back and forth, the second air passage communicates with the clearance formed between the syringe needle and the installation passage through the radial passage on the inner wall of the middle section of the installation passage. Since this clearance remains in communication with the air guide hole provided on the surface of the syringe needle to communicate with the syringe needle air passage, the second air passage is also in communication with the syringe needle air passage for air delivery. And when delivering air, the parts on both sides of the middle section of the installation passage still remain sealed with the syringe needle to prevent air leakage.

[0025] Furthermore, a clearance fit is formed between the middle section of the installation passage 13 and the syringe needle 4 through a groove 14. The groove 14 is an arc-shaped groove extending in the circumferential direction or a continuous annular groove in the circumferential direction. The length of the projection of the groove 14 along the radial direction of the installation passage 13 matches the stroke of the movement of the syringe needle 4. The groove 14 can be provided on the surface of the syringe needle 4, or on the inner wall of the installation passage 13, or grooves 14 are provided on both the surface of the syringe needle 4 and the inner wall of the installation passage 13. In this embodiment, the groove 14 is preferably an annular groove continuous around the circumference, and the annular groove is provided on the inner wall of the installation passage 13. The installation passage 13 in this embodiment is the lumen of a sleeve 15. The sleeve 15 is sealingly sleeved in a transition chamber 16 provided in the gun body 2. The axes of the sleeve 15, the transition chamber 16, and the syringe needle 4 coincide. Both ends of the transition chamber 16 communicate with the piston chamber 6 and the material chamber 1-1 respectively. The front end of the sleeve 15 is tightly and sealingly fitted with the transition chamber 16 through a sealing ring 17. The rear end of the sleeve 15 is tightly fitted with the transition chamber 16 by providing a plurality of stepped round tables. The syringe needle 4 passes through the sleeve 15. Both ends of the sleeve 15 are sealingly connected to the inserted syringe needle 4 through a sealing ring 17. A first radial passage 18 penetrating the side wall of the sleeve 15 is provided on the inner wall of the lumen of the sleeve 15. The two ends of the first radial passage 18 extend and expand around the circumference on the inner wall of the lumen of the sleeve 15 and the outer wall surface of the sleeve 15 to form an arc-shaped groove or an annular groove. The air guide hole 4-3 communicates with the arc-shaped groove or the annular groove on the inner wall of the lumen. Here, the inner wall of the lumen is preferably an annular groove continuous around the circumference as the groove provided on the inner wall of the installation passage 13. The second air passage 11 communicates with the arc-shaped groove or the annular groove on the outer wall surface of the sleeve 15. Here, an outer annular groove 25 continuous around the circumference is preferably selected.

[0026] The installation channel is formed on a separate sleeve member. The sleeve can be independently manufactured in batches. When the paint spray gun is assembled, the sleeve is hermetically sleeved and fixed with the transition cavity provided inside the gun body. The needle passes through the sleeve and can move normally. The two ends of the sleeve and the inserted needle are hermetically connected without air leakage. The second air passage successively passes through the outer ring groove on the outer wall of the sleeve, the first radial passage penetrating the side wall of the sleeve, and the groove on the inner wall of the sleeve cavity of the sleeve, and communicates with the air guide hole on the needle, and then communicates with the needle air passage.

[0027] Further, the base 8 is perpendicular to the gun body 2 and integrally formed therewith. The air inlet passage 9 and the second air passage 11 are respectively Figure 4 a large-diameter passage and a small-diameter passage with coaxial butt joints as shown, and a toroidal surface 19 is formed at the butt joint. One end of the large-diameter passage away from the toroidal surface 19 extends to the outer end surface of the base 8 to form an installation hole 8-1. The adjustment switch 12 is an adjustment rod that hermetically penetrates into the large-diameter passage, that is, the air inlet passage, from the installation hole 8-1. Here, the adjustment rod is inserted and installed in the base 8 through a tail seat 20. The adjustment rod is inserted on a tail seat 20 and threadedly connected thereto. The tail seat 20 is provided with an installation portion 20-1 sleeved in the installation hole 8-1 and fixedly connected to the base 8. Here, the installation portion 20-1 and the installation hole 8-1 are also threadedly connected for convenient disassembly and assembly. The adjustment rod includes a thin rod section 12-1 at the front section and a threaded section 12-2 at the rear section. The diameter of the thin rod section 12-1 is smaller than that of the threaded section 12-2. The diameter of the threaded section 12-2 is smaller than the inner diameter of the large-diameter passage. The thin rod section 12-1 penetrates into the large-diameter passage, and the threaded section 12-2 is threadedly connected to the tail seat 20. One end of the small-diameter passage corresponding to the second air passage 11 away from the toroidal surface 19 extends to the inner wall surface of the transition cavity 16 to form an opening communicating with the outer ring groove 25. An opening is provided on the inner wall of the large-diameter passage corresponding to the air inlet passage 9 and extends along the direction parallel to the axis of the gun body 2 to form a first air passage 10 communicating with the piston cavity 6. One end of the first air passage 10 away from the large-diameter passage extends to form an opening on the inner wall of the piston cavity 6. An air inlet of the base communicating with the air inlet passage 9 is opened at the position of the side wall of the base 8 outside the gun body 2 and connected to an air delivery pipe 26. Figure 4 The arrow in Figure 3 shows the compressed air from the air delivery pipe presented by a stepped section.

[0028] During use, the adjustment rod is rotated forward and backward to move it in and out of the air inlet passage. The distance between the inner end of the adjustment rod and the toroidal surface 19 also changes accordingly, and the air flow rate input from the large-diameter passage to the small-diameter passage changes. For better fine adjustment of the air flow rate, both the toroidal surface 19 and the inner end of the adjustment rod are in a frustoconical shape. The inner end of the adjustment rod is a frustoconical end 12-3, and the taper of the toroidal surface is greater than that of the frustoconical end. In addition, the toroidal surface can also be a plane, and the inner end of the adjustment rod can also be of other shapes, as long as the two match to adjust the air flow rate.

[0029] Furthermore, a positioning device for restricting the backward movement stroke of the piston 3 is also provided at the rear end of the gun body 2. The positioning device includes a tail cap 21 and a screw rod 22 passing through it. The screw rod 22 is threadedly connected to the tail cap 21. A barrel cavity with an open end facing backward is provided at the rear end of the gun body 2. The tail cap 21 is fixedly connected to the barrel cavity to cover the open end, and together with the barrel cavity, it forms the piston cavity 6. The two ends of the spring 7 respectively abut against the piston 3 and the tail cap 21. A locking member 23 is sleeved on the rod section of the screw rod 22 extending out of the piston cavity 6, and the locking member 23 is threadedly connected to the screw rod 22. The screw rod can abut against the backward moving piston to limit its position. By rotating the screw rod to adjust the length of its screwing into the barrel cavity, the backward movement stroke of the piston can be restricted. Furthermore, the backward movement position of the gun needle and the discharge amount of the nozzle can also be locked accordingly. The length of the screw rod screwing into the barrel cavity is inversely proportional to the backward movement stroke of the piston. Since the paint spray gun will frequently switch between gas supply / air cut-off during the spraying process, each time the gas is re-supplied, the piston will move backward under the action of air pressure and impact the screw rod. Tightening the locking member so that it abuts against and presses the tail cap can lock the screw rod to the tail cap, preventing the adjusted screw rod from being repeatedly collided by the piston and causing loosening and displacement.

Claims

1. A paint spray gun, comprising a gun body (2) connected to the bottom of a material storage tank (1) and a piston (3) and a gun needle (4) arranged therein and moving synchronously, a nozzle (5) with a spray hole (5-1) is arranged at the front end of the gun body (2), a material chamber (1-1) connected to the material storage tank (1) is arranged in the middle section of the gun body (2), a piston chamber (6) matched with the piston (3) is arranged at the rear end of the gun body (2), the gun needle (4) seals through the piston chamber (6) and extends into the material chamber (1-1), a spring (7) is arranged in the piston chamber (6) to press against the piston (3) so that the gun needle (4) tends to move forward to block the nozzle, a gun needle air channel (4-1) is arranged in the gun needle (4), the gun needle air channel (4-1) extends to the front end surface of the gun needle (4) to form a blowing hole (4-2), the gun needle (4) can change the gap with the spray hole (5-1) as the piston (3) moves, and is characterized in that The gun body (2) is provided with a pipe seat (8), and a gas transmission passage with one inlet and two outlets is provided in the pipe seat (8), and the gas transmission passage includes an air inlet passage (9) and a first air passage (10) and a second air passage (11) connected thereto. The pipe seat (8) is provided with an opening to communicate with the air inlet passage (9), the first air passage (10) communicates with the piston chamber (6), and the second air passage (11) communicates with the gun needle air passage (4-1). The pipe seat (8) is provided with an adjusting switch (12) capable of changing the air transmission flow of the second air passage (11).

2. The paint spray gun according to claim 1, characterized in that A mounting hole (13) is provided between the material cavity (1-1) and the piston cavity (6), the axes of the mounting hole (13) and the piston cavity (6) coincide, the gun needle (4) passes through the mounting hole (13) and extends into the material cavity (1-1), an air guide hole (4-3) is provided on the surface of the gun needle (4) to communicate with the gun needle air channel (4-1), the middle section of the mounting hole (13) and the gun needle (4) are gap-matched, and a radial hole is provided on the inner wall of the mounting hole (13) corresponding to the middle section, the inner and outer ends of the hole are respectively connected to the gap and the second air channel (11), the mounting holes (13) and the gun needle (4) on both sides of the middle section are sealed, and during the movement of the gun needle (4), the air guide hole (4-3) keeps connecting the gap formed by the middle section of the mounting hole (13) and the gun needle (4).

3. The paint spray gun according to claim 2, characterized in that A clearance fit is formed between the middle section of the mounting hole (13) and the gun needle (4) through a groove (14), wherein the groove (14) is an arc groove extending in the circumferential direction or a continuous annular groove in the circumferential direction, and the length of the radial projection of the groove (14) along the mounting hole (13) matches the travel of the gun needle (4).

4. The paint spray gun according to claim 3, characterized in that The groove (14) is arranged on the surface of the gun needle (4) or the inner wall of the installation channel (13), or the surface of the gun needle (4) and the inner wall of the installation channel (13) are both provided with the groove (14).

5. The paint spray gun according to claim 2, characterized in that The installation channel (13) is a tube cavity of a sleeve (15). The sleeve (15) is sealed and sleeved in a transition cavity (16) provided in the gun body (2). The axes of the sleeve (15), the transition cavity (16) and the gun needle (4) coincide with each other. The two ends of the transition cavity (16) are connected to the piston cavity (6) and the material cavity (1-1) respectively. The gun needle (4) passes through the sleeve (15). The two ends of the sleeve (15) are sealed with the inserted gun needle (4) through sealing rings (17). The inner wall of the tube cavity of the sleeve (15) is provided with a first radial channel (18) penetrating the side wall of the sleeve (15), and the two ends of the first radial channel (18) extend around the circumference on the inner wall of the tube cavity of the sleeve (15) and the outer wall surface of the sleeve (15) to form an arc groove or annular groove, the air guide hole (4-3) is connected to the arc groove or annular groove on the inner wall of the tube cavity, and the second air channel (11) is connected to the arc groove or annular groove on the outer wall surface of the sleeve (15).

6. The paint spray gun according to claim 5, characterized in that The tube seat (8) is perpendicular to the gun body (2) and is an integral structure therewith; the air inlet (9) and the second air channel (11) are respectively a large-diameter channel and a small-diameter channel coaxially butted together, and a ring surface (19) is formed at the butt joint; one end of the large-diameter channel away from the ring surface (19) extends to form a mounting hole (8-1) on the outer end surface of the tube seat (8); the regulating switch (12) is an regulating rod that seals and penetrates the large-diameter channel from the mounting hole (8-1); the diameter of the rod section of the regulating rod that penetrates into the large-diameter channel is smaller than the inner diameter of the large-diameter channel; the regulating rod can be adjusted by moving in and out of the large-diameter channel The distance between the inner end of the variable rod and the annular surface (19) is used to adjust the air flow rate of the large-diameter channel input into the small-diameter channel; the end of the small-diameter channel away from the annular surface (19) extends to the inner wall surface of the transition chamber (16) to form an opening; the inner wall of the large-diameter channel is provided with an opening and extends along a direction parallel to the axis of the gun body (2) to form a first air channel (10) connected to the piston chamber (6); the end of the first air channel (10) away from the large-diameter channel extends to the inner wall of the piston chamber (6) to form an opening; the side wall of the tube seat (8) is provided with a through hole at a position outside the gun body (2) to connect to the air inlet channel (9).

7. The paint spray gun according to claim 6, characterized in that The adjusting rod is inserted into a tailstock (20) and is threadedly connected thereto. The tailstock (20) is provided with a mounting portion which is sleeved in the mounting hole (8-1) and is tightly connected to the pipe seat (8). The adjusting rod comprises a thin rod section (12-1) at the front section and a threaded section (12-2) at the rear section. The diameter of the thin rod section (12-1) is smaller than the diameter of the threaded section (12-2), and the diameter of the threaded section (12-2) is smaller than the inner diameter of the large-diameter channel.

8. The paint spray gun according to claim 6, characterized in that The annular surface (19) is a plane; or the annular surface (19) and the inner end of the adjusting rod are both in the shape of a frustum, and the taper of the annular surface (19) is greater than the taper of the inner end of the rod.

9. The paint spray gun according to any one of claims 1 to 8, characterized in that The rear end of the gun body (2) is provided with a positioning device capable of limiting the backward movement of the piston (3), the positioning device comprising a tail cap (21) and a screw rod (22) passing therethrough, the screw rod (22) and the tail cap (21) being threadedly connected, the rear end of the gun body (2) is provided with a barrel cavity open to the rear, the tail cap (21) is fixedly connected to the barrel cavity to cover the opening, and together with the barrel cavity, forms the piston cavity (6), and the two ends of the spring (7) respectively abut against the piston (3) and the tail cap (21).

10. The paint spray gun according to claim 9, characterized in that The screw rod (22) is sleeved with a locking piece (23) on the rod section extending out of the piston chamber (6), and the locking piece (23) and the screw rod (22) are threadedly connected.

Images