Retractable pipe assembly of air blow gun

A retractable pipe assembly of an air blow gun includes an extension pipe, a lock unit and a blow pipe. The extension pipe has a stepped through hole which has a large diameter part and a small diameter part for insertion of the blow pipe. One end of extension pipe has an inner inclined surface which is inclined inward. The lock unit includes a lock member. The lock member is connected to the extension pipe. An elastic collet and a seal member are provided in the lock member. Because the inner inclined surface of the extension pipe guides the seal member and the elastic collet pushes the seal member, the seal member is deformed to tighten the blow pipe and to seal the extension pipe. The elastic collet can clamp the blow pipe and won't damage the blow pipe.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a retractable pipe assembly of an air blow gun, and more particularly to a retractable pipe which can be adjusted in a stepless way and connected with more pipe assemblies.

2. Description of the Prior Art

As shown inFIG. 8andFIG. 9, a conventional retractable pipe of an air blow gun comprises an extension pipe50. One end of the extension pipe50is connected to an air blow gun5. The extension pipe50has an end head51at the other end thereof. A washer61and an O-shaped ring62are provided in the end head51of the extension pipe50. The distal end of the end head51is provided with an O-shaped ring63and connected with a metallic sleeve70. The sleeve70comprises an elastic collet71at a front end thereof to connect with a nut72. A pipe80has one end inserted into the extension pipe50and passing the washer61and the O-shaped ring62. The distal end of the pipe80is connected with a stop ring81. The pipe80is movable in the extension pipe50and can be secured by screwing the nut72, achieving retraction and extension of the pipe80.

As shown inFIG. 8, the sleeve70is made of metal. In particular, the elastic collet71must be processed for grooves73. This causes high cost and is time-consuming. Sometimes, the edges of the grooves73have remained iron filings to damage the surface of the pipe80during installation.

The elastic collet71made of metal is used to clamp the pipe80. Both the elastic collet71and the pipe80are made of hard material. When they are contact with each other, the surface of the pipe80may have a clamping dent. If the user pulls the pipe80carelessly, the elastic collet71may scrape the surface of the pipe80to leave burrs which may damage the O-shaped ring62when retracting the pipe80. This will cause leakage of compressed air and shorten the service life of the pipe.

The elastic collet made of metal must be processed for the grooves to cause high cost and time waste. The edges of the grooves have remained iron filings to damage the surface of the pipe during installation. Both the elastic collet and the pipe are made of hard material. When they are contact with each other, the surface of the pipe may have a clamping dent to damage the O-shaped ring when retracting the pipe. This will cause leakage of compressed air. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a retractable pipe assembly of an air blow gun. The retractable pipe assembly comprises an extension pipe, a lock unit and a blow pipe. The extension pipe comprises a front connecting end and a rear connecting end. The front connecting end and the rear connecting end respectively have threads thereon. The extension pipe has a stepped through hole which has a large diameter part, a small diameter part and a stepped stop between the large diameter part and the small diameter part. The lock unit comprises a lock member, an elastic collet and a seal member. The lock member has a first end and an opposing second end. The first end of the lock member has an inner threaded hole. The second end of the lock member has a through hole which has a diameter smaller than that of the inner threaded hole. The through hole communicates with the inner threaded hole. The elastic collet and the seal member are accommodated in the lock member. The inner threaded hole of the lock member is threadedly connected to the threads of the front connecting end of the extension pipe. One end of the elastic collet has a cone surface. The cone surface has a plurality of slots which are disposed around the cone surface. The blow pipe is inserted in the stepped through hole of the extension pipe. The blow pipe comprises a stop ring screwed to an end of the blow pipe. The stop ring is accommodated in the extension pipe and stopped by the stepped stop.

Preferably, the front connecting end of the extension pipe has an inner inclined surface at an end edge thereof. The inner inclined surface is inclined inward.

Preferably, the extension pipe is further connected with another extension pipe.

The elastic collet of the present invention is made of an engineering plastic material, which is light, can be moved smoothly, can be manufactured easily and quickly, and is cost-effective. The material of the elastic collet is elastic to provide a better tightening force and won't damage the surface of the blow pipe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown inFIG. 1throughFIG. 3, the retractable pipe assembly of an air blow gun according to a preferred embodiment of the present invention comprises an extension pipe10, a lock unit20, and a blow pipe30.

The extension pipe10comprises a front connecting end11and a rear connecting end12. The front connecting end11and the rear connecting end12respectively have threads111,121thereon. The rear connecting end12is connected with a connector13to connect an air blow gun40. The extension pipe10has a stepped through hole14which has a large diameter part, a small diameter part and a stepped stop141between the large diameter part and the small diameter part. The small diameter part of the stepped through hole14is disposed at the front connecting end11to support the blow pipe30. The front connecting end11has an inner inclined surface112at an end edge thereof. The inner inclined surface112is inclined inward.

The lock unit20comprises a lock member21, an elastic collet22and a seal member23. The lock member21has a first end and an opposing second end. The first end of the lock member21has an inner threaded hole211. The second end of the lock member21has a through hole212which has a diameter smaller than that of the inner threaded hole211. The through hole212communicates with the inner threaded hole211. The elastic collet22and the seal member23are accommodated in the lock member21. The inner threaded hole211of the lock member21is threadedly connected to the threads111of the front connecting end11of the extension pipe10. The seal member23is located on the inner inclined surface112of the extension pipe10. The second end of the lock member21has an inner cone surface213therein. One end of the elastic collet22has a cone surface221corresponding to the inner cone surface213of the lock member21. The cone surface221has a plurality of slots222which are disposed around the cone surface221. The cone surface221can be deformed to provide a clamp effect.

The blow pipe30is inserted in the stepped through hole14of the extension pipe10and is retractable in the extension pipe10. The blow pipe30comprises a stop ring31screwed to an end of the blow pipe30. The stop ring31has a diameter larger than that of the blow pipe30. The stop ring31is accommodated and movable in the large diameter part of the stepped through hole14of the extension pipe10. The stop ring31of the blow pipe30is confined by the small diameter part of the stepped through hole14and stopped by the stepped stop141, so that the blow pipe30will not disengage from the extension pipe10.

As shown inFIG. 4andFIG. 5, the blow pipe30is controlled by the lock unit20to be secured or adjusted in a stepless way. The lock member21can be loosened to disengage from the elastic collet22, so that the elastic collet22is returned to its original state, as shown inFIG. 5. The blow pipe30is released from the elastic collet22, so that the blow pipe30can be moved in the extension pipe10or turned to a desired angle.

As shown inFIG. 1throughFIG. 4, when the blow pipe30is extended to the utmost length, the stop ring31is confined and stopped by the stepped stop141of the stepped through hole14, so that the blow pipe30won't disengage from the extension pipe10.

The blow pipe30is positioned by screwing the lock member21. The lock member21gradually tightens the elastic collet22to hold against the cone surface221of the elastic collet22. The cone surface221is gradually deformed to clamp and position the blow pipe30.

As shown inFIG. 1, the elastic collet22is made of an engineering plastic material, which is light, can be moved smoothly, can be manufactured easily and quickly, and is cost-effective. Through the design of the slots222, the elastic collet22can be deformed to clamp the blow pipe30. The material of the elastic collet22is elastic to provide a better tightening force and won't damage the surface of the blow pipe30.

Referring toFIG. 1andFIG. 3, the seal member23of the lock unit20is located between the elastic collet22and the inner inclined surface112of the extension pipe10. The seal member23of the lock unit20is pushed by the elastic collet22when screwing the lock member21and guided by the inner inclined surface112of the extension pipe10to be deformed so as to tighten the blow pipe30and to seal the extension pipe10. Thus, the seal member23has a seal effect to the blow pipe30, preventing a leak of compressed air from the lock unit20.

As shown inFIG. 3andFIG. 6, through the connector13, the present invention is coupled to an air blow gun40which can be in different types for different uses. The blow pipe30is retractable in a stepless way, which can be extended to its utmost in order to enter a dangerous location or a narrow seam for spraying compressed air. The present invention can be used conveniently.

Referring toFIG. 1andFIG. 2, the inner cone surface213of the lock member21and the cone surface221of the elastic collet22have the same taper. Through the inner cone surface213of the lock member21to hold against the cone surface221of the elastic collet22, the elastic collet22is gradually compressed to clamp the blow pipe30. The retraction of the elastic collet22can be operated smoothly to clamp the blow pipe30tightly, and the elastic collet22won't damage the surface of the blow pipe30.

Referring toFIG. 7, the present invention comprises a plurality of extension pipes10which are connected in series. In this embodiment, there are three connected extension pipes10,10A,10B. The distal end of the extension pipe10B is connected with the blow pipe30. The lock unit20,20A,20B are connected between the extension pipes10,10A,10B or between the extension pipe10B and the blow pipe30to form a multi-section extension pipes10,10A,10B to couple with the blow pipe30, so that the length of the extension pipe10can be increased. The blow pipe30can reach a further deeper location for a large-scale machine. The extension pipe can be retracted to decrease the spaced occupied.

Accordingly, through adjustment of the lock member of the lock unit of the present invention, the blow pipe of the air blow gun can be adjusted and positioned. The blow pipe is retractable in a stepless way, which can be extended to its utmost in order to enter a dangerous location or a narrow seam for spraying compressed air. The elastic collet is light, can be moved smoothly, can be manufactured easily and quickly, and is cost-effective. The material of the elastic collet is elastic to provide a better tightening force and won't damage the surface of the blow pipe.