US3508740A - Band tensioning tool - Google Patents

Description

April 28, 1970 B. s. PALMER 3,

BAND TENSIONING TOOL Filed Sept. 14, 1967 2 Sheets-Sheet 2 IN VEN TOR United States Patent 3,508,740 BAND TENSIONING TOOL Basil Stoddard Palmer, 22 East St., Titchfield, Fareham, Hampshire, England Filed Sept. 14, 1967, Ser. No. 667,724 Claims priority, application Great Britain, Oct. 27, 1966, 48,186/ 66 Int. fl. B21f 45/18; B66f 19/00 US. Cl. 254 7 Claims ABSTRACT OF THE DISCLOSURE It is an object of the invention to provide an improved device for tensioning the banding wire, making use of pneumatic or hydraulic power. Another object of the invention is to provide means whereby the degree of ten- SlOl'l applied to the band or wire may be preset. The improved device operates in conjunction with a clip forming an anchorage for one end of the band or wire to be tensioned along the article to be banded, while the free end of the band or wire passes through the clip and is clamped to the banding device, the tension being produced by relative displacement of the clip and clamp.

Broadly, the invention consists in a device for tensioning a band or wire, comprising a housing in which a piston is movably disposed, means being provided for subjecting the piston to hydraulic or pneumatic power, the piston being arranged for displacing a carrier of a wire or band gripping member, the piston also being arranged for actuating the wire or band gripping member into gripping engagement with the wire or band, the arrangement being such that the wire or band gripping member is actuated by the piston prior to movement of the said carrier by the piston.

In order to make the invention clearly understood, reference will now be made to the accompanying drawings which are given by way of example and in which:

FIG. 1 is a sectional view of a banding device of the invention, shown in engagement with a band;

FIG. 2 is a sectional view along the line IIII of FIG. 1; and

FIG. 3 is a sectional view along the line IIIIII of FIG. 1.

The banding device comprises a housing having a body portion 1 and an end portion 2. These portions are secured together by a tie rod 5 and screws 22. On the tie rod 5, a piston 3 is movably guided, the piston having an O-ring seal 29 which engages the cylindrical surface of the tie rod 5, and a cup-seal 28 which engages the surface of a cylindrical bore in the body portion 1 of the housing.

The banding device is intended to grip the free end of banding material 34 which extends around an article to be banded, the other end of the banding material 34 being fixed to a clip 33 through which the free end of the banding material 34 is to be drawn by the banding device. Accordingly, a pusher plate 13 fixed by screws 21 to the body portion 1 of the housing is provided for engaging the clip 33. Slots 35 are provided in the housing for passage of the banding material 34 therethrough. For engaging the free end of the banding material 34 and applying a tractive force there'o, a gripping arrangement is provided. This comprises an involute cam or pawl 6 which is mounted by a pivot pin 9 in a carrier 4 which is movably guided on the tie rod 5. The pawl 6 is retained on the pivot pin 9 by a spring clip 26. The carrier 4 is additionally guided on a rod 20 which extends between the portions 1 and 2 of the housing.

The piston 3 is urged in the direction away from the end cap portion of the housing by springs 18 which are mounted on guides 11. The portion 1 of the housing has an abutment surface 3 so positioned that it acts as a stop for an abutment surface 37 of the pawl carrier 4 when the piston 3 is moved towards its left hand end position, engagement between the surfaces 36 and 37 taking place shortly before the piston reaches its left hand end position, for example A5 of an inch before.

A spring 19 mounted on a spigot 12 extending from the carrier 4 is provided which tends to draw the piston 3 towards the carrier 4, but this tendency is resisted by the springs 18 which are stronger than the springs 19.

The piston 3 is fitted with an axially extending connecting rod 7, which is secured thereto by means of a grub screw 23. The connecting rod 7 is linked to the pawl 6 by means of a pin 8 so that if the piston 3 is axially moved from its left hand end position as viewed in FIG. 1, the movement of the connecting rod 7 will cause the pawl 6 to rotate about the pivot pin 9, in the clockwise direction as viewed in FIG. 1. Such rotation of the pawl 6, due to its involute configuration, will cause the pawl to grippingly engage the banding material 34, the gripping action being between the pawl 6 and a platform-like portion 38 of the carrier 4. Thus, movement of the piston 3 away from its left hand end position as viewed in FIG. 1 will first cause the pawl 6 to be rotated so as to grippingly engage the banding material 34 and thereafter movement of the piston 3 moves the connecting rod 7 which in turn will cause the carrier 4, together with the pawl 6 to be axially moved along the tie rod 5, thus applying a tractive force to the banding material 34. It will be appreciated that the gripping is effected during rotation of the cam 6 and the actual tensioning of the banding material 34 is subsequently produced by translation of the pivot pin 9. The distinction between the gripping and tensioning functions is enabled by ensuring that the piston 3, when commencing movement from its left hand position, can move through a predetermined amount before the carrier 4 is moved away from the abutment 36. The instant at which the carrier 4 moves away from the abutment 36 is the transistion instant between the gripping and tensioning functions.

Since the pawl 6 is in etfect a simple lever, the gripping force on the banding material 34 is proportional to the applied power pressure and thus the resultant tension in the banding material is similarly proportional. By making the cam face of the pawl 6 of involute configuration, a constant leverage action is obtained, irrespective of the thickness of the banding material.

If 'the piston 3 completes its full travel before the desired tension in the banding material is achieved, then the pressure medium behind the piston 3 is expelled through a vent 39 in the body portion 1 of the housing.

' Expulsion of the pressure medium in this way gives an audible indication of incorrect tensioning.

Pressure medium is supplied to the device through a connection 17 in a handle 27. The handle 27 carries a control valve retained by a grub screw 24, the valve having a spool 15 and an operating button 16. The spool has seals in the form of O- rings 30, 31 and 32 and is arranged for controlling pressure medium passages in known manner so that depending on the way in which the valve is operated by means of the button 16, pressure medium can be applied to the left hand side of the piston 3 or the space at the left hand side of the piston 3 can be vented to the outside atmosphere.

In use of the device, the banding material 34 is passed around an article to be banded, and in such a way that the free end of the banding material 34 passes through the clip 33. The pusher plate 13 is then engaged with the clip 33 and the valve is operated by means of the button 16 so that pressure medium is admitted to the space at the left hand side of the piston 3. This causes movement of the piston 3, the initial part of the movement being effective through the connecting rod 7 for rotating the pawl 6 into gripping engagement with the banding material 34. Subsequent movement of the piston 3 then results in axial movement of the carrier 4 and the consequent application of tension to the banding material 34. When the desired tension in the banding material 34 has been achieved, the operating valve may be maintained in the open position and it is then possible for the operator to continue with any other necessary operations such as soldering or clinching the clip, while the banding device maintains tension in the banding material.

Release of the banding material subsequent to these operations is effected by moving the operating valve into the closed position. This interrupts the supply of pressure medium to the cylinder in which the piston 3 is movable, and thence the said cylinder to the outside atmosphere. The piston return springs 18 are then able to return the piston 3 and the carrier 4 to their original positions, and during this return action, the abutment surface 37 provided on the carrier 4 engages against the abutment surface 36, thus arresting the carrier 4, continued movement of the piston 3 towards its left hand position thus resulting in anti-clockwise movement of the pawl 6 and consequent release of the banding material 34 thereby.

It will be appreciated that the tension applied to the banding material 34 depends on the extent to which the piston 3 is displaced in its cylinder subsequent to the banding material having been firmly gripped by the pawl 6. For enabling the tension in the banding material to be set at a desired value, a pressure controlling device, such as a conventional throttle valve V, may be provided in a pressure medium line 40 between the banding device and the source of pressure medium. Such a pressure controlling device may be of known construction and enables the pressure applied to the left hand side of the piston 3 to be maintained at a predetermined adjustable value. In one known form of such a pressure controlling device, a pressure gauge is provided which registers the pressure which the system has reached.

Irrespective of whether or not a pressure controlling device is provided, the source of pressure medium may be an existing pressure line or a foot pump or other pump. In order that the tension in the banding material is retained, non-return valve means should be provided for preventing escape of pressure medium prior to fixing of the clip 33. Such non-return valve means would normally be provided in the above-mentioned pressure controlling device.

It will be appreciated that the banding device of the invention enables the band or wire to be automatically gripped on the commencement of tensioning, and released after tensioning, this allowing easy insertion of the band or wire into the gripping mechanism. The arrangement of the gripping pawl 6 makes it possible for the gripping mechanism to grip purely by frictional action so that damage to the band or wire is avoided. This makes it possible for the band or wire to be drawn from a coil without wastage. Moreover, the lever action of the pawl 6 enables different widths and thicknesses of band or wire to be automatically accommodated. Additionally, the construction is such that all moving parts are totally enclosed except for the insertion slots for the band or wire, this making the device safe to the user, while at the same time excluding dirt.

I claim:

1. A device for tensioning an elongated banding material, comprising a housing, a piston movably disposed in said housing, means for subjecting said piston to pressure fluid power, a carrier displaceable by said piston, a gripping member for said material, said gripping member being carried by said carrier, means connecting said piston to said gripping member for actuating said gripping member into gripping engagement with said material said material said connecting means being so arranged that said gripping member is actuated by the piston prior to movement of said carrier by the piston.

2. A device as defined in claim 1, comprising a connecting rod carried by said piston and linked to said gripping member for moving said carrier after the actuation of said gripping member.

3. A device as defined in claim 2, wherein said gripping member is a cam pivoted on said carrier.

4. A device as defined in claim 3, wherein said cam has a gripping surface of involute shape.

5. A device as claimed in claim 1, wherein said carrier has a platform-like surface and said gripping member is arranged to grip the banding material by cooperating with said platform-like surface.

6. A device as defined in claim 1, comprising a pressure medium line leading to said tensioning device, and a pressure controlling device in said line whereby to provide a controllable operating pressure for said tensioning device which allows the tension in the banding material to be predetermined.

7. A device as defined in claim 1, wherein a vent is provided in said housing and so positioned that it is uncovered by the pressure-impacted side of said piston when said piston reaches the extreme limit of its working stroke, but is not uncovered by the said side of said piston during a piston stroke corresponding to less than the full stroke possible.

References Cited UNITED STATES PATENTS 2,864,582 12/1958 Hall 254--51 3,090,599 5/1963 Weiss 254-51 3,173,456 3/1965 Bailey 254-5l X ROBERT C. RIORDON, Primary Examiner D. R. MELTON, Assistant Examiner U.S. Cl. X.R. 93,2

Images