FASTENER INSTALLATION SYSTEM WITH SPLIT TOOL HEAD AND ACTUATION BASE

Abstract

A fastener application device comprising an hydraulically-operated tool head held by an operator and having an actuator trigger, a base structure having an air-operated power cylinder operatively attached to an hydraulic cylinder to supply hydraulic pressure to the tool head in response to operation of the actuator trigger. The tool head and base structure are connected only by air and oil lines that are long enough to allow the base structure to be supported on, for example, a workbench, requiring the tool operator to support only the weight of the tool head during a fastener installation sequence.

Claims

1. A method for installing fasteners using a hydraulic tool to execute pull and return movements comprising the steps of: providing a tool head adapted to receive and operate a hydraulic tool through pull and return movements wherein said tool head includes a handle and trigger connected to operate an air valve in the tool head; providing a power base vessel having a pressurized air inlet and containing a lower air chamber having a piston therein and an upper hydraulic reservoir having a piston therein, the air chamber and oil reservoir pistons being mechanically interconnected such that movements of the air chamber piston pressurized oil in the oil reservoir; providing a pair of air lines interconnecting the tool head air valve to the power base vessel; and providing a closed loop hydraulic circuit including a pair of hydraulic lines interconnecting the oil reservoir to the tool head to cause the tool head to cycle a tool in the tool head, when installed, through pull and return movements; lifting only the tool head into position to install a fastener; and operating the trigger to direct air to the air chamber to produce movements of the interconnected air chamber piston and oil reservoir piston thereby to operate a tool in the tool head, when installed, through said pull and return functions.

2. A method for installing fasteners with an operator-handled system for performing pull and return functions on a fastener comprising the steps of: Providing a tool head with a trigger-operated air valve; Providing a base vessel structurally separate from the tool head capable of resting independently on a support surface and having an air-operated hydraulic reservoir connected to the tool head by a pair of flexible oil lines forming a closed-loop hydraulic circuit with the tool head; Lifting the tool head into a fastener-applying position without simultaneously lifting the base vessel; and Operating the air valve with the tool head trigger to pressurize the oil lines in sequence to perform the pull and return functions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The disclosed device and the novel aspects of it will be best understood by reference to the attached drawings of which:

[0010] FIG. 1 is a perspective view of the split system showing the air cylinder base with integral hydraulic cylinder, lever arm, and throttle valve, and the separate tool head, the base and tool head being interconnected by air and oil lines;

[0011] FIG. 2 is an exploded view of the tool head and a portion of the pneumatic/hydraulic actuator system components; and

[0012] FIGS. 3 and 4 are sectional diagrams of the pneumatic/hydraulic cylinder and tool head in the pull and return cycle positions, respectively.

DETAILED DESCRIPTION

[0013] Referring to the drawings, FIG. 1 shows the overall device to comprise a tool head 10 having a handle 12 with an operator-controlled actuator lever or trigger 14 that is pulled to initiate a lockbolt installation sequence. The tool head has a fitting 11 to receive a nose assembly for, by way of example, a lockbolt fastener installation involving a pull and return cycle.

[0014] The device further includes a base 18 housing an air cylinder having a piston 36 and an inlet 20 for air from a compressor (not shown). The base housing 18 includes an integral upper housing 26 and a reverse-acting pneumatic cylinder 28. Housing 26 has a side portion 27 that holds a vertical rod 34 connected to control a lever arm 24 pivotally mounted on top of the larger-diameter portion of the base further includes a throttle valve 22 controlled by the position of the lever arm 24. The weight of the base structure is about 11 pounds.

[0015] Referring to FIGS. 3 and 4, more detail is shown. The throttle valve 22 is operated in part by an internal spring 42 that pushes up, and in part by the lever arm 24 which is toggled back and forth by means of the rod 34 in the cylinder 27. The rod is operated by the reverse acting air cylinder 28 which is mounted on block 25 on top of the hydraulic cylinder in housing 26. Hydraulic lines 30 interconnect the hydraulic cylinder housing 26 with the tool head 10 to operate the tool head by air pressure in a manner to be described. In addition, air lines 32 interconnect the base with the tool head such that operation of the actuator trigger 14 can initiate a pull sequence as described below.

[0016] FIG. 3 shows the device in a pull cycle, wherein the tool head 10 operates by way of a piston 40 to pull on the nose assembly (not shown) to the right as shown in FIG. 3 to initiate the first step in a fastener installation process. Depressing the actuator 14 causes air to flow through line 32a to the reverse acting cylinder 28 which pulls the rod 34 up. This lifts the right side of pivotally mounted lever arm 24 upwardly as shown in FIG. 3. This causes the left-hand side of the pivotally mounted lever arm 24 to move downwardly. This downward movement pushes the main body of the throttle valve 22 down against the action of return spring 42 causing air under pressure to flow to the bottom side of the air-operated power piston 36 while air above the piston is routed through the valve 22 to an exhaust 48. This pushes the piston rod assembly 38, 39 upwardly, applying pressure to the closed-loop hydraulic fluid reservoir 46, which in turn pressurizes a line 30 and pushes against the piston 40 in the tool head to move the piston from left to right as shown in FIG. 3. When the actuator 14 is released, the rod 34 moves down, allowing the spring 42 to push the throttle valve upwardly, applying air pressure to the top of the air piston 36 and exhausting air below the piston as shown in FIG. 4.

[0017] During the return cycle, air from the top of the piston 36 is exhausted through the center of the throttle valve and into the exhaust port 48. The hydraulic system is a closed-loop system of fixed volume and can be cycled in both directions. The air system is open-loop and requires constant input of air pressure from a conventional compressor via fitting 20.

[0018] The reverse-acting air cylinder 28 uses an internal spring 29 to reverse after the actuator 14 is released, cutting off air to the cylinder. This type of cylinder can be replaced with a reverse-acting cylinder that uses air for the return motion via an additional air line connection. These alternatives provide equivalent operation in a substantially similar fashion.

[0019] Summarizing, the actuator trigger 14 causes air to flow to the cylinder 28 which then toggles the lever arm 24 to cause the valve 22 to admit to and exhaust air from the power piston 36. That, in turn, powers the hydraulic cylinder 34 to supply hydraulic oil under pressure to the tool head.

[0020] As described the system overall allows the operator to bear only the weight of the tool head, while the base 18 can be separately supported on, for example, a work bench or cart. The hydraulic and air lines are the only weight-bearing connectors between the base structure 26 and the tool head 10 and can be as long as necessary to achieve the desired mobility, but a typical length is from 4 to 8 feet.