GB2055321A - Improvements in package strapping apparatus - Google Patents

Abstract

In a package strapping tool of the "pusher-bar" type which does not have a fixed base plate under the overlapping strapping portions to be joined, the joint is by interengaging incisions made in the strapping by a punch 104 vertically movable by a pneumatic ram assembly 27 into and out of engagement with a die element 105. The die element is provided on pivoted jaws 106 which are swung apart to allow the strapping to be inserted and then swung together under the strapping. The ram assembly 27 drives a toothed rack (not shown) in engagement with a gear sector having an arm 42 pivoted to a link 102 which together form a toggle linkage for moving the punch 104. The rack has projections 111 in which are angled slots 110 engaged by pins 109 on the jaws 106. On the initial downward movement of the rack the jaws 106 are swung together by the action of the angled ends of the slots 110. The pins 109 then enter extents 112 of the slots parallel to the direction of motion of the projections 111 so locking the jaws in their closed position while the punch 104 moves towards the die elements 105. Finally pins 117 moving with the punch 104 engage holes 118 in the jaws 106 preventing the jaws from separating under and then swung together under punch pressure. <IMAGE>

Description

SPECIFICATION Improvements in package strapping apparatus This invention relates to package strapping apparatus of the kind in which the joint made by the apparatus in overlapping portions at the ends of a loop of metal strapping has interengaging formations between the overlapping strapping portions to make a joint between them without the addition of a seal or sleeve around the overlapping portions.

By convention in the industry package strapping apparatus is divided into tools and machines. A package strapping tool is an appliance which is brought to the packages, bundles or other articles to be strapped and may be manually or power operated. A package strapping machine is one which is stationary and to which packages or other articles are brought to be strapped.

In one known form of package strapping tool of this kind the interengaging formations are made by a punch and die on opposite faces of the strapping. The punch is usually mounted on a base plate of the tool over which the overlapping portions of strapping extend and the die is slidably mounted for axial movement towards and away from the punch to make the interengaging formations.

For use on certain kinds of package, particularly those which are incompressible, the presence of the base between the strapping and the package prevents satisfactory tightening of the loop.

In another form of tool pivoted jaws straddle opposite edge of the strapping and cooperate with a fixed punch to form incisions in the overlapping portion. in service pivots of the jaws wear and the jaws deflect outwardly resulting in excessive clearance between cutting edges of the punch and jaws impairing the efficiency of the joint and eventually in failure to make a joint at all.

It is an object of the present invention to provide a package strapping apparatus which reduces or avoids these difficulties.

The present invention consists in package strapping apparatus of the kind in which a joint between overlapping portions at the ends of a loop of metal strapping is made by a punch and die, disposed respectively on opposite faces of the strapping, which form interengaging formations in the overlapping portions upon axial relative movement between the punch and die wherein one element of the punch and die is formed by a pair of jaws movable between an operative position in which the jaws are closed and said one element can co-operate with the other element of the punch and die to form the interengaging formations on relative axial movement of the punch and die and an inoperative position in which the jaws are open and separated to admit the strapping between the punch and die.

The incisions for forming the interengaging formations are not made during the closing of the jaws to bring them to the operative posi tion but subsequently by relative axial move ment of the punch and die. The jaws are not under load during their closing and opening movement so that wear on the pivots is light.

Closing of the jaws serves not only to bring them into operative relationship with the other element of the punch and die but to capture the overlapping portions of the loop of strapp ing inserted between the jaws before the jaws were closed.

Pins and sockets are preferably provided between the punch and die which co-operate when the punch and die are brought together and locate the jaws in their operative position while the interengaging formations are made.

The pins and sockets substantially prevent deflection due to movement about the pivots of the jaws. Deflection is substantially con fined within the jaws themselves.

The invention may be advantageously ap plied to any of the various types of package strapping tools and machines in which seal less joints are already known. it may also enable the use of seal-less joints to be ex tended to package strapping tools and ma chines, particularly automatic machines on which joints including a seal or sleeve are more usual.

Preferably the jaws are of L-section each pivotally mounted near the upper ends of a longer limb of the L-section which extends beyond the pivot and carries a transverse pin engaging an angled slot or groove defined by means linearly movable towards and away from the pivot. The angling of the slots and the direction of linear movement of the said means is arranged to close and open the jaws on movement of the linearly movable means.

The slots may each include an extent parallel to the direction of linear movement of the linearly movable means. While the pins are traversing this extent there is no relative movement of the jaws which are thus held locked in the closed position.

The extent may be such, for example of sufficient length, as to permit the linearly movable means further movement after the jaws have been closed, allowing the linearly movable means to be actuated by means which also performs some other operating function.

Preferably the jaws are opened and closed by actuating means which also causes the axial relative movement of the punch and die.

The actuating means may be manual or be power operated. As the jaws constitute an element of the punch and die set clearly the mechanism provided for this combined actua tion must enable the closing movement of the jaws to be completed before the punch and die set begins to operate on the strapping. An angled slot of linearly movable means, as previously described, is one example of a convenient mechanism for this purpose.

The jaw movement and the relative axial movement of the punch and die may conveniently both be effected by fluid pressure means such as a fluid pressure operated ram assembly. The early part of a stroke, for example the outward stroke, of a plunger or piston of the ram assembly may then be utilised to close the jaws and the later part to form the joint by relative axial movement of the punch and die.

The package strapping apparatus may include means for tensioning the loop of strapping around a package. The free end of the strapping may be anchored by forming it into a hook shape which engages around the closed jaws when tension is applied. The hook-shaped end is towards the surface of the package and lies against the surface of the closed jaws which faces towards the package and away from the other element of the punch and die. When the joint has been completed and the tool removed, the hookshaped end lies between the joint and the surface of the package.

Alternatively the tensioning means may include a gripper for holding the strapping near the free end of the loop. The free end need not then be hooked around the closed jaws.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a front view of one form of strapping tool according to the invention, Figure 2 is an end view in the direction of arrow II in Fig. 1, Figure 3 is a view similar to Fig. 1 but partly in section, Figure 4 is a partial section on line IV-IV of Fig. 3, Figure 5 is a fragmentary section on line V-V of Fig. 3, Figure 6 is a sectional view similar to Fig. 3 at a different stage in the operation of the tool and on line VI-VI of Fig. 7, Figure 7 is a partial section on line VII-VII of Fig. 6, Figure 8 is a further sectional view similar to Fig. 3 at another stage in the operation of the tool and on line VIII-VIII of Fig. 9, Figure 9 is a partial section on line IX-IX of Fig. 8, and Figure 10 is a perspective view of a completed package strapping joint made by the strapping tool of Figs. 1 to 9.

The strapping tool illustrated in Figs. 1 to 9 of the drawings is operated by compressed air and is of the so-called "pusher bar" type. The strapping tool comprises an air-driven tensioning motor assembly 20 for tightening a metal strap 21 around the package, a jointing device 22 for securing together overlapping portions of the strap 21 by interengaging formations 23 (Fig. 10), constituting a "seal-less" type joint, and a valve assembly 24 by which the operation of the strapping tool is controlled.

The tensioning motor assembly 20 and the jointing device 22 are both pivoted to a frame 25 to enable the tool to be opened for easier engagement with a loop of strapping and closed for operating upon it.

The jointing device 22 is operated by a fluid pressure operated ram assembly in form of a large double-acting piston and cylinder assembly 27 with a piston 28 (Fig. 3) working in a cylinder formed in a housing 29. The piston 28 is mounted on a piston rod 30 which extends through the bottom of the housing 29.

Below the housing 29 extends a mounting boss 31 for the jointing device 22. Spaced parallel rectangular plates 35, 36 and 37 are secured to the mounting boss 31 by bolts 38 and there are further bolts 39, fitted with spacing tubes 39', connecting the lower edges of the plates 35, 36 and 37, which form front, intermediate and back plates respectively. A toothed rack 32 integral with the piston rod 30 lies between the intermediate plate 36 and the back plate 37. A crosshead 33 is vertically slidably mounted between the front plate 35 and the intermediate plate 36.

A gear sector 34 pivotally mounted by a pin 40 on the crosshead 33 extends through a slot 41 in the intermediate plate 36 to mesh with the gear rack 32. The gear sector 34 has an upwardly extending arm 42 giving the gear sector 34 the form of a bell-crank. The end of the arm 42 is pivotally connected by a pin 43 to one end of a link 102 the other end of which is pivotally anchored to the mounting boss 31 by a pin 103. The arm 42 and link 102 form a toggle linkage. When the piston 28 moves downwards the rack 32 and sector 34 bring the arm 42 and link 102 towards an in-line position in which the mechanical advantage, with which the crosshead 33 is moved downwards, approaches a maximum. One element of a punch and die, as illustrated a punch element 104, is mounted on the lower end of crosshead 33 and moves therewith. The other element of the punch and die set, as illustrated a die element 105, is formed on a pair of jaws 106 of L-section (Fig. 4) the die element 105 being formed on a shorter limb of the L-section. Near the upper ends of a longer limb of the L-section the jaws 106 are pivotally mounted by pins 107 between the plates 35 and 36. Beyond the pivots the jaws 106 have upward arms 108 which carry transverse pins 109 extending from the arms 108 to engage angled slots 110 in lateral projections 111 (Figs. 1, 4, 7 and 9) integral with the rack 32. The slots 110 have long extents 11 2 which are straight and parallel to the rack 32 and short angled portions 11 3 inclined inwards one towards the other.The pins 109 engage the closed ends of the angled portions 11 3 when the piston 28 is at the top of its stroke (Figs. 3 and 4). As the piston 28 begins to move downwards the pins 109 are moved away from one another by the downward movement of the inclined portions 11 3 of the slots 11 3 swinging the lower part of the jaws 106 inwards and towards each other until the pins 109 enters the extents 11 2 (Figs. 6 and 7).

For the remainder of the downward movement of the piston 28 and rack 32, necessary for the operation of the punch and die set, no further movement of the jaws 106 occurs and the jaws are held in the closed position as the long extents 11 2 are parallel to the direction of movement of the rack 32. Depending from the crosshead 33 on opposite sides of the punch element 104 are locking pins 11 7 (Fig.

7) which engage sockets 11 8 in the jaws 106 as the crosshead moves to the lowest part of its downward movement (Fig. 9). Engagement of the locking pins 11 7 and sockets 11 8 resists deflection of the jaws 1 06 while the punch element 104 and die element 105 cooperate to form incisions 114 (Fig. 1 0) and make a joint between overlapping strap portions disposed between them.

The jointing device 22 is pivoted to the frame 25 by a pivot pin 45 which passes through lugs 46 projecting from the back plate 37 and a bore in the frame 25. Forming part of the frame 25 is a strap foot 47 which tapers towards a toe 48. In the closed positions of the tool the toe 48 bears against the bottom edge of the intermediate plate 36 and the front edge projects forward to a position in which it co-operates with a cutter 44 mounted on the punch element 104, to sever surplus strapping from the completed joint.

The motor assembly 20 is pivoted to the frame 25 by a pivot pin 49. A rotary dog 50 for tensioning the strap is driven by an air motor 51 of the motor assembly 20 through suitable gearing. A pad 52 is mounted in the strap foot 47 opposite the rotary dog 50 to support the strap against the pressure of the rotary dog during tensioning.

A hand lever 53 rigidly mounted on the frame 25 extends above the body of the motor 51. By squeezing the hand lever 53 and motor 51 together, the motor 51 can be raised to life the rotary dog 50 away from the strap foot to enable the strap to be inserted between the rotary dog 50 and the pad 52. A barrel-shaped compression spring 54 mounted between a bracket 55 rigid with the hand lever 53 and a lug 51 (Fig. 6) on the casing of the motor assembly urges the rotary dog 50 towards the pad 52. An outrigger bracket 56 supported by the motor pivot 49 carries an outer end bearing for the shaft on which the rotary dog 50 is mounted. A downward projection 57 of the outrigger bracker forms an outer edge strap guide. Outside the outrigger bracket 56 a strap foot restrainer 59 is swivelly mounted on the motor pivot 49.On its inner face the strap foot restrainer 59 has an arcuate groove 60 (Fig. 3) to receive a lateral projection 61 on the strap foot when the strap foot restrainer 59 is swung downwards. The under face of the projection 61 has a curved surface centred on the motor pivot 49 and engages the facing side of the groove 60 to resist deflection of the strap foot during strap tensioning. A link 62 couples the strap foot restrainer 59 to an auxiliary doubleacting piston and cylinder assembly 63. The link 62 is pivotally connected to the strap foot restrainer 59 and to a piston rod 64. A cylinder 65 (Fig. 3) of the piston and cylinder assembly 63 is formed in a body 66 of the valve assembly 24 and its piston 67 is connected to the piston rod 64.In its outstroking direction the piston 67 swings the strap foot restrainer 59 clockwise (as viewed in Figs. 3 and 6) engaging the lateral projection 61 with the groove 60. The movement continues until the strap foot restrainer 59 meets a peg 68 protruding from the outrigger bracket 56 on which it acts to urge the motor assembly 20 about the motor pivot 49 in a clockwise direction (as shown in Fig. 6) so as to urge the rotary dog 50 harder against the strapping. If frictional contact between the strap foot restrainer 59 and the strap foot 47 has not already caused the strap foot 47 to move towards the jointing device 22, the force applied to the strap foot 47 through the rotary dog 50, by the action of the auxiliary piston and cylinder assembly 63, will urge the toe 48 of the strap foot 47 towards the back plate 37.

In the opposite direction the auxiliary piston and cylinder assembly 63 moves the strap foot restrainer 59 anti-clockwise, disengaging its groove 60 from the lateral projections 61 and out of the way of the strap being inserted between the rotary dog 50 and the pad 52.

Towards the end of the anti-clockwise movement of the strap foot restrainer 59 a tail 69 of the strap foot restrainer 59 engages an abutment 70 (Figs. 1 and 3) on the frame 25 so that the strap foot restrainer 59 and the frame 25 together move anti-clockwise about the pivot pin 45 swinging the strap foot 47 away from the back plate 37 ready for en gagement of the tool with the loop of strapping. On the underside of the strap foot 47 an inverted channel 11 5 is formed (Fig. 5) to receive a part of a strapping loop, as will be described later. Spring loaded plungers 11 6 are provided in the walls of the channel to retain the strapping.

In the cylinder housing 29 above the large piston 28 is a small co-axial partial-close cylinder 71 (Figs. 3, 6 and 8) with a piston 72 which abuts the large piston 28 when the piston 28 is at the top of its stroke. When air under pressure is admitted to the top of the partial close cylinder 71, the piston 72 moves from the position shown in Fig. 3 and bears on the large piston 28 and moves the piston rod 30 to close the jaws 106 around the strap 21 (as shown in Fig. 7) whilst strap tensioning takes place. By this means the strap 21 is retained and prevented from being pulled out of the jaws as a result of curvature or irregularities in the package surface.

At the bottom of the cylinder housing 29 a plunger 73 (Fig. 6) is slidably mounted for movement parallel to the piston rod 30. It is spring biased to project into the cylinder.

Towards the lower end of its stroke the piston 28 depresses the plunger 73 indicating that the jointing operation powered by the piston and cylinder assembly 22 has been completed. The way in which use is made of this indication will be described later.

A spring-returned, pivoted tension valve lever 78 (Fig. 1) operates a tension valve within the valve assembly 24 and when depressed supplies air under pressure to the top of the piston 67 of the auxiliary piston and cylinder assembly 63, and opens its underside to atmosphere, supplies air to the air motor 51 and to the top of the co-axial cylinder 71 through a passage 99 (Fig. 3). The underside of the large piston 28 is also opened to atmosphere. The passage 99 includes a screw-down valve 100 which enables the passage 99 to be restricted in order that the build up of air pressure in the co-axial cylinder 71 can be delayed to prevent the premature closing of the jaws 106 so as to allow time for ensuring that the strap is properly in place between them.

Similarly a spring-returned, pivoted jointing valve lever 79 (Fig. 3) provides manual control of a jointing valve within the valve assembly 24. Moving the jointing valve lever 79 downwards supplies pressure air to the top of the cylinder of the main piston and cylinder assembly 27. A catch 82 (Fig. 6) pivotally mounted between the lever 78 and 79 is urged by a spring 83 towards engagement with the tension valve lever 78. The catch 82 self-engages the tension valve lever 78 when that lever is depressed and holds it down. The catch 82 also has a tail (not shown) which lies under the jointing valve lever 79. When the jointing valve lever 79 is depressed it engages this tail and trips the catch 82 disengaging it from the tension valve lever 79. However, rigid with the jointing valve lever 79 is a holddown pin 86 (Fig. 1) which projects over the tension valve lever 78.When the catch 82 is tripped the tension valve lever 79 rises into engagement with the hold-down pin 86 but not sufficiently to alter the effective position of the tension valve.

A cranked lever 87 (Fig. 1) is pivotally mounted at an intermediate point in its length to the body 66 of the valve assembly 24. The flower end of the cranked lever 87 extends under the edge of the cylinder housing 29 and has a lateral extension 89 which is bifurcated and embraces a circumferential groove 90 (Fig. 8) in the plunger 73 where it projects below the cylinder housing 29. The upper end of a helical compression spring 91 surrounds a spigot 92 at the lower end of the plunger 73. The lower end of the spring 91 is received in a pocket 93 (Fig. 3) in a lug 94 projecting from the back plate 37. The spring 91 urges the plunger 73 upwards and the cranked lever 87 in an anticlockwise direction in Fig. 3.At its upper end the cranked lever 87 has a lateral projection 95 (Fig. 8) which extends towards the jointing lever 79 and lies in the path which a lateral projection (not shown) on the jointing lever 79 follows when the jointing lever 79 is depressed. Meeting faces on the projection 95 and the lateral projection on the jointing lever 79 respectively are complementarily inclined so that when the jointing lever 79 is depressed the projection on the jointing lever defiects the projection 95, moving the cranked lever 87 (clockwise in Fig. 8) against the action of the spring 91 until the projection 95 has passed the projection on the jointing lever, when the spring urges the projection 95 to overlie the projection on the jointing lever and retain the jointing lever 79 in the operative position.The plunger 73, cranked lever 87, spring 91 and the overlapping projections, thus constitutes a self-engaging latch to retain the jointing lever 79 in the operative position until the plunger 73 is engaged by the piston 28 at the end of its downwards movement. The piston 28 reaches this position when the jointing operation has been completed. Depression of the plunger 73 by the piston 28 releases the latch so that the jointing lever 79 withdraws the hold-down pin 86 from the tension lever 78 which, too, returns to its initial position by its spring return.

A summary of the full cycle of operation of the strapping tool is as follows. In the starting condition shown in Figs. 3 and 4 pressure air is being supplied through the valve controlled by jointing lever 79 to the under side of the piston 28 so that the jaws 106 are held wide open and the punch element 104 is at the top of its stroke. Pressure air is also being supplied by the valve controlled by tension lever 78 to the underside of the piston of the auxiliary piston and cylinder assembly 63.

This holds the strap foot restrainer 59 in its upper position and the toe 48 of the strap foot 47 is separated from the intermediate plate 36.

A length of strapping 21 drawn from a supply reel is looped around a package and the free end bent under to form a hook 101.

Alternatively the length of strapping 21 may be pre-cut to an adequate length for the packages to be bound. An end portion 21' of the loop remote from the hook is inserted sideways into the tool between the rotary dog 50 and the pad 52. To create a gap for this purpose between the rotary dog 50 and the pad 52 the air motor 51 is lifted by squeezing together the air motor 51 and the hand lever 53. A portion 21" of the strapping between the hook 101 and the loop is inserted in the channel 11 5 and retained there by the spring loaded plungers 11 6. The overlapping portions of the now upper strapping portion 21' and lower strapping portion 21" lie below the punch element 104 and the strap foot occupies the angle between adjacent parts of the strapping portions 21' and 21".

The tension lever 78 is then depressed and is held in this position by the catch 82. The resulting reversal of the pressure air supply to the auxiliary piston and cylinder assembly 63, so that it is now applied to the top of the piston, closes the strap foot restrainer 59 (as shown in Fig. 6), urges the strap foot towards the back plate 37, and urges the rotary dog 50 against the upper strapping portion 21'.

Air pressure is simultaneously applied to the partial-close cylinder 71 and, after a slight delay produced by the screw-down valve 100 to allow the operator to check that the overlapping portions of strapping are properly located between the jaws 106, the jaws 106 close and capture the overlapping strapping portions as shown in Fig. 6.

Pressure air is also applied to the air motor 51 which drives the rotary dog 50 to tension the strapping. As the loop is tightened the lower portion 21" of the strapping is anchored by the engagement of the hook 104 with the sides of the jaws 106 (see Fig. 8).

The strapping is fully tensioned when the motor stalls. The operator then depresses the jointing lever 79 to apply air pressure to the top of the piston 28. The crosshead 33 moves down and, before the punch element 104 and die element 105 begin to make the incisions 11 4 in the overlapping strapping portions, the locking pins 11 7 engage the sockets 11 8 (see Figs. 8 and 9) to prevent movement of the jaws 106 as previously described and hold the die element 105 in proper relation with the punch element 1 04. The incisions 114 produce interengaging formations 23 making a joint between the overlapping ends of the loop of strapping.At almost the end of the downward stroke of the crosshead 33 the cutter 44 co-operates with the toe 48 of the strap foot to cut the loop from the supply of strapping or from the spare material of a precut length. When the main piston 28 reaches the bottom of its stroke, on completing the jointing and cutting off operation, it strikes the plunger 73 so that the jointing lever 79 is released as previously described.

Release of the jointing lever 79 also releases the tension lever 78 cutting off the pressure air supply to the motor and supplying it instead to the underside of the main piston 28, re-opening the jaws 106 so that the tool can be removed from the package.

Pressure air is also applied to the bottom of the piston of the auxiliary piston and cylinder assembly 63 swinging the strap foot restrainer 59 up into the open position and bringing its tail 69 into engagement with the abutment 70 to withdraw the strap foot 47 from the back plate 37 ready for the next loop of strapping.

As an alternative to the arrangement described, if the pad 52 is given a serrated or other gripping surface, the lower strapping portion 21" may be taken with the upper strapping portion 21' over the strapping foot 48 instead of under it. When the strapping is being tensioned the upper strapping portion 21' slides over the lower strapping portion 21" which is held by the grip of the pad 52.

Bending of the lower strapping portion 21" to form the hook 101 would then be unnecessary.

Instead of actuation of the jointing mechanism by the jointing lever 79, automatic initiation of the jointing operation may be provided, for example, in accordance with our published patent application No. 2023073 (7918446).

Although the invention has been described in relation to a tool of the pusher bar type, the punch and die arrangement described may be applied to other types of strapping tools and to automatic machines, either to replace jointing mechanisms of the kind making use of a seal or sleeve applied around the overlapping portions or as a substitute for other "seal-less" types of jointing mechanisms. In such tools and machines the punch and die may be operated by similar means to that described in connection with the illustrated embodiment or by other suitable pneumatic, hydraulic or mechanical means.

Claims (14)

1. Package strapping apparatus of the kind in which a joint between overlapping portions at the ends of a loop of metal strapping is made by a punch and die, disposed respectively on opposite faces of the strapping, which form interengaging formations in the overlapping portions upon axial relative movement between the punch and die wherein one element of the punch and die is formed by a pair of jaws movable between an operative position in which the jaws are closed and said one element can co-operate with the other element of the punch and die to form the interengaging formations on relative axial movement of the punch and die and an inoperative position in which the jaws are open and separated to admit the strapping between the punch and die.

2. Package strapping apparatus according to Claim 1 wherein interengageable pin and socket pairs are provided, the pin and socket of each pair being disposed one on the punch and the other on the die and co-operating when the punch and die are brought together to locate the jaws in the operative position while the punch and die close to form the interengaging formations.

3. Package strapping apparatus according to Claim 1 or Claim 2 wherein the jaws are of L-section pivotally mounted about parallel axes near those ends of longer limbs of the Lsection jaws which are remote from the angle of the L-section and in such a way that the jaws straddle the edges of the strapping, the L-section jaws having shorter limbs which extend one towards the other and by which the said other element of the punch and die set is formed.

4. Package strapping apparatus according to Claim 3 wherein the longer limb of each jaw extends beyond the pivotal axis and carries a transverse pin engaging an angled slot or groove defined by means linearly movable towards and away from the pivot, the angling of the slots and the direction of linear movement of the said means being arranged to close and open the jaws on movement of the linearly movable means.

5. Package strapping apparatus according to Claim 4 wherein each slot or groove includes an extent parallel to the direction of linear movement of the linearly movable means.

6. Package strapping apparatus according to Claim 5 wherein the extent is such as to permit the linearly movable means further movement after the jaws have been closed and allows the said means to be moved by means which also performs some other operating function.

7. Package strapping apparatus according to any one of preceding Claims 1 to 3 wherein the jaws are opened and closed by actuating means which also causes the axial relative movement of the punch and die.

8. Package strapping apparatus according to Claims 6 and 7 wherein the linearly movable means is moved by the actuating means.

9. Package strapping apparatus according to Claim 7 or Claim 8 wherein the actuating means is a fluid-pressure operated ram assembly.

10. Package strapping apparatus according to Claim 9 wherein the early part of a stroke in one direction of a plunger or piston of the fluid-pressure operated ram assembly is operative to close the jaws and the later part to cause the relative axial movement of the punch and die.

11. Package strapping apparatus according to Claim 9 or Claim 10 wherein is provided a toothed rack linearly movable by the ram assembly, a pivoted gear sector in mesh with the toothed rack and a toggle linkage of which the gear sector forms a link and which is arranged to cause the relative axial movement of the punch and die on linear movement of the toothed rack.

1 2. Package strapping apparatus according to Claim 11 as appendant to Claim 8 wherein the linearly movable means is formed by projections on opposite sides of the toothed rack, each of the projections including an associated one of the angled grooves or slots.

1 3. Package strapping apparatus according to any one of the preceding claims wherein means is provided for partly closing the jaws to cause the jaws to ernbrace and hold captive the overlapping portions of the strapping.

14. Package strapping apparatus according to Claim 13 as appendant to Claim 9 wherein the means for partly closing the jaws comprises a secondary fluid pressure operated ram assembly.

1 5. Package strapping apparatus according to Claim 1 3 or Claim 14 which includes means for tensioning the loop of strapping around a package prior to making the joint between the overlapping portions of the strapping wherein a control for initiating the operation of the tensioning means is also arranged to start, after a time delay, operation of the means for partly closing the jaws.

1 6. Package strapping apparatus according to any preceding claim and which is of the pusher bar type in which a frame supporting tensioning means is hinged to a support for the punch and die, the frame including a wedge-shaped strap foot which in use of the apparatus is disposed between the loop of strapping close to the overlapped ends of the loop and an adjacent supply or spare end of the loop wherein the side of the strap foot adjacent the loop has means for retaining the loop.

1 7. Package strapping apparatus according to Claim 1 5 wherein the means for retaining the loop comprises a channel to receive the strapping and spring-loaded means for holding the shipping in the channel.

1 8. Package strapping apparatus substantially as described herein with reference to, and as illustrated by, the accompanying drawings.