Barrel assembly for a rivet gun

A barrel assembly for a rivet gun has a barrel, a piston, a rear plug, a fluid tube, a control valve tube and a spring. The barrel has a cavity. The piston is mounted slidably in the cavity and has a rivet ejection passageway. The rear plug is mounted on a rear end of the barrel and has an assembling hole and a sliding passageway. The fluid tube is mounted detachably in the rear end of a head of the piston. The control valve tube is detachably mounted on the rear end of the fluid tube and is mounted slidably in the sliding passageway. With the fluid tube and the control valve tube, the barrel assembly efficiently prevents the high pressure air from continuously leaking out after the pin pulling action is finished.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a barrel assembly, and more particularly to a barrel assembly for a rivet gun that prevents pneumatic cylinder from outputting high pressure air after an operation of pulling a rivet is completed, which reduces high pressure air consumption.

2. Description of Related Art

A conventional rivet gun is used to rivet two boards such that the boards are securely mounted together by rivets. A rivet has a cap and a core pin. The cap is T-shaped and has an enlarged end and a mounting end. The core pin is mounted longitudinally through and protrudes out of the cap and has two ends and a ball formed on one end and adjacent to the mounting end of the cap.

A conventional rivet gun comprises a barrel, a handle, a trigger, a pin collector and a pneumatic cylinder.

The barrel has a front end, a rear end and a vise assembly that may vise and pull a core pin of a rivet on the front end into the barrel. The handle is mounted perpendicularly on the barrel and has air passageways. The collector is a jar mounted on the rear end of the barrel to collect the ejected core pins. The pneumatic cylinder is mounted movably under the handle and capable of activating the vise assembly through pneumatic and hydraulic means. Furthermore, the pneumatic cylinder may be connected to a high-pressure air source such as an air bottle to implement the ejection of the core pin.

When the rivet gun is used to rivet two pieces such as boards or plates together, a rivet is mounted through the pieces. The enlarged end of the cap of the rivet abuts an inside piece, and the front end of the barrel of the rivet gun abuts the enlarged end. The trigger is pulled to activate the vise assembly to pull a core pin on the cap into the barrel. The ball on the core pin longitudinally compresses and radially expands the mounting end of the cap into T-shape so that the expanded mounting end hooks on an outside piece to complete the riveting process. Then, the air output by the high-pressure air source flows through the barrel from the front end to the rear end and sucks the broken core pin vised by the vise assembly backward into the collector.

Furthermore, a bypass hole is defined through the barrel and communicates with the air passageways. Therefore, when the trigger is pulled, the high pressure air in the pneumatic cylinder passes through air passageways and the bypass hole into the barrel and drives the vise assembly to move backward to pull the rivet.

However, after the vise assembly completes the action of pulling the rivet and stays at a rear position, the pneumatic cylinder continues outputting high pressure air through the bypass hole to external atmosphere, which meaninglessly consumes the high pressure air.

To overcome the shortcomings, the present invention provides a barrel assembly to mitigate or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

The main objective of the invention is to provide a barrel assembly for a rivet gun that prevents pneumatic cylinder from outputting high pressure air after an operation of pulling a rivet is completed, which reduces high pressure air consumption.

A barrel assembly for a rivet gun in accordance with the present invention has a barrel, a piston, a rear plug, a fluid tube, a control valve tube and a spring. The barrel has a cavity. The piston is mounted slidably in the cavity and has a rivet ejection passageway. The rear plug is mounted on a rear end of the barrel and has an assembling hole and a sliding passageway. The fluid tube is mounted detachably in the rear end of a head of the piston. The control valve tube is detachably mounted on the rear end of the fluid tube and is mounted slidably in the sliding passageway. With the fluid tube and the control valve tube, the barrel assembly efficiently prevents the high pressure air from continuously leaking out after the pin pulling action is finished.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference toFIGS. 1 and 2, a barrel assembly for a rivet gun in accordance with the present invention comprises a barrel10, a piston20, a rear plug30, a fluid tube50, a control valve tube60and a spring40.

With further reference toFIGS. 3 and 4, the barrel10has a cavity100, an inner thread101, a mounting hole105, a high pressure inlet hole107and a handgrip sleeve11.

The cavity100is defined axially in a rear end of the barrel10.

The inner thread101is formed on an inner surface of the cavity100near the rear end of the barrel10.

The mounting hole105is defined axially in a front end of the barrel10and communicates with the cavity100.

The high pressure inlet hole107is defined radially in the barrel10and communicates with the cavity100.

The handgrip sleeve11is formed radially on the barrel10and has a sleeve hole110and a hydraulic hole115. The sleeve hole110is defined axially in a bottom of the handgrip sleeve11and may accommodate a handgrip. The hydraulic hole115is defined in the handgrip sleeve11and is disposed between and communicates with the cavity100and the sleeve hole110.

The piston20is mounted slidably in the cavity100of the barrel10and has a head21, a rod22and a rivet ejection passageway200.

The head21is mounted slidably in the cavity100of the barrel10, airtightly contacts the inner surface of the cavity100, and has a mounting slot210. The mounting slot210is defined in a rear end of the head21.

The rod22is formed on and protrudes forward from the head21and extends through the mounting hole105of the barrel10.

The rivet ejection passageway200is defined through the head21and the rod22.

The rear plug30is mounted detachably on the rear end of the barrel10and has an assembling hole300, an outer thread31and an airflow controlling tube35.

The assembling hole300is defined axially in a front end of the rear plug30.

The outer thread31is formed on an outer surface of the rear plug30and is engaged detachably with the inner thread101of the barrel10.

The airflow controlling tube35is formed in the assembling hole300and has a sliding passageway350and a sealing ring351. The sliding passageway350is defined axially through the airflow controlling tube35. The sealing ring351is mounted on an inner surface of the sliding passageway350near a front end of the sliding passageway350.

The fluid tube50is mounted detachably in the rear end of the head21of the piston20and has a front end, a rear end, a rivet ejection hole500, an outer threaded portion55and an outer conical surface58.

The front end of the fluid tube50is mounted detachably in the mounting slot210of the head21.

The rivet ejection hole500is defined axially through the fluid tube50and communicates with the rivet ejection passageway200.

The outer threaded portion55is formed on an outer surface of the fluid tube50.

The outer conical surface58is formed on the rear end of the fluid tube50.

The control valve tube60is detachably mounted on the rear end of the fluid tube50, is mounted slidably in the sliding passageway350of the airflow controlling tube35, airtightly contacts the sealing ring351in the sliding passageway350, and has a rivet ejection channel600, at least one valve hole63, an inner threaded portion65and an inner conical surface608.

The rivet ejection channel600is defined axially through the control valve tube60and communicates with the rivet ejection hole500of the fluid tube50.

The at least one valve hole63is defined radially in the control valve tube60, communicates with the rivet ejection channel600and selectively moves in or out of the sliding passageway350. When the control valve tube60slides to a forward position relative to the sliding passageway350, the at least one valve hole63moves out of the sliding passageway350and communicates with the cavity100such that the cavity100communicates with the rivet ejection channel600and the rivet ejection hole500. When the control valve tube60slides to a backward position relative to the sliding passageway350, the at least one valve hole63moves in the sliding passageway350and is isolated from the cavity100such that the cavity100is isolated from the rivet ejection channel600and the rivet ejection hole500.

The inner threaded portion65is formed on an inner surface of the rivet ejection channel600at a front end of the rivet ejection channel600and is engaged with the outer threaded portion55.

The inner conical surface608is formed on the inner surface of the rivet ejection channel600, surrounds the outer conical surface58with an interval defined between the inner conical surface608and the outer conical surface58.

Sliding the control valve tube60controls high pressure air of a high-pressure air source connected to the rivet gun to flow from the cavity100to the rivet ejection channel600.

The spring40is mounted around the fluid tube50and the airflow controlling tube35and has two ends respectively abutting the fluid tube50and the rear plug30.

With reference toFIG. 4, when the rivet gun is triggered to pull a pin of a rivet, the control valve tube60, fluid tube50and piston20move forward such that the at least one valve hole63moves out of the sliding passageway350. At the meantime the high pressure air enters the cavity100through the high pressure inlet hole107, sequentially passes through the at least one valve hole63, the rivet ejection channel600, and the sliding passageway350, and then is finally discharged backward out of the barrel10. The high pressure air drives a broken pin of a rivet inside the barrel10to move back through the rivet ejection passageway200and the sliding passageway350and out of the barrel10. The discharged broken pin finally falls into a pin collector that is connected to the rear end of the barrel10.

With reference toFIG. 5, when the pin pulling action is completed, the control valve tube60, fluid tube50and the piston20move backward to move the at least one valve hole63back into the sliding passageway350such that the cavity100is re-isolated from the rivet ejection channel600and the sliding passageway350to prevent the high pressure air from continuously leaking out.

The barrel assembly in accordance with the present invention efficiently prevents the high pressure air from continuously leaking out after the pin pulling action is finished. Furthermore, the fluid tube50and the control valve tube60are detachable and replaceable to facilitate maintenance of the rivet gun and applicability for different rivet guns.