FIELD OF THE INVENTION The present invention relates to a tool block for use as part of a forming machine. More particularly, although not exclusively, the present invention relates to a tool block for a rollforming machine. Even more particularly, although not exclusively, the present invention relates to a tool block for retaining a dimpling die punch and associated second die. Even more particularly, although not exclusively, the present invention relates to a tool block formed so that a dimpling die punch or other tool can locate into a groove or slot in the tool block and remain in a fixed position during use, the die punch or other tool easily removed from the groove or slot, in particular without further disassembly of either the die punch or the rest of the apparatus being required.

The present invention also relates to a dimpling die punch tool. More particularly, although not exclusively, the present invention relates to a dimpling die punch sub-assembly for a rollforming machine. Even more particularly, although not exclusively, the present invention relates to a dimpling die punch formed so as to have improved structural strength and reliability characteristics. Even more particularly, although not exclusively, the present invention relates to a dimpling die punch formed to locate into a groove or slot in a tool housing and remain in a fixed position during use, and which can be easily removed from the groove or slot, in particular without further disassembly of either the die punch or the rest of the rollforming machine being required.

The present invention also relates to a tool and tool block in combination. BACKGROUND

In a rollforming process, sheets of material such as steel sheet are fed into a rollforming machine and undergo various forming operations such as bending, hole punching, dimpling and similar. It is common for the rollformed sheets to have subsequent operations performed on them, for example for a sheet to be riveted or screwed to a separate item such as one or more other sheets, or for two edges of the same sheet to be riveted together. If the sheet is to be riveted or screwed, it is common practice during the rollforming operations to form a dimple in the sheet into which the head of the rivet or screw can sit flush or semi-flush with the surface of the material, with a hole formed in the bottom of the dimple through which the shaft of the rivet or screw passes. To create the dimple, the sheet is fed between two parts of a forming tool - a moving die part and a stationary dimple part (or the other way round), the inner faces of each part aligned and having a complimentary shape - a dish-shaped or concave depression on one, and a complimentary concave portion on the other. As the sheet passes between the two parts, they are forced together, usually by a hydraulic ram or similar associated with the moving part, the moving part forced towards the stationary part, trapping the sheet between the convex and concave inwards faces so that a dimple is formed in the sheet. The two parts then move apart, the sheet moves on, and the process repeats. Dimples are formed in specific places on the sheet, the locations controlled by the machine's control software.

The moving part is usually hydraulically actuated in order to provide the considerable necessary force to deform and punch through sheet steel. Effectively the two die halves are hammered together (with the sheet forming an intervening layer). The repeated hammering operation causes high stresses in the die components, and failures are common. In particular, failures are common in the stationary die, which is subjected to repeated strikes from the hydraulically actuated moving die. These failures result in downtime and repair expense, as well as the expense from lost productivity. As the two dies are usually located close to one another in order to minimise the gap through which the sheet passes, the problem can be exacerbated as sometimes partial or total disassembly of the hydraulic actuator is required in order to access the damaged die for repair or replacement.

It is an object of the present invention to provide a tool block which goes some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice.

It is a further object of the invention to provide a dimpling die punch which goes some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice.

It is a yet still further object of the invention to provide a tool block and tool in combination which go some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice.

Various advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing the preferred embodiment of the invention without placing limitations thereon.

The background discussion (including any potential prior art) is not to be taken as an admission of the common general knowledge. Throughout this specification, the word "comprise", or variations thereof such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

SUMMARY OF THE INVENTION

In a first aspect the invention may broadly be said to consist in a tool block and tool for a roll-forming machine:

the tool block comprising a substantially u-shaped body with substantially parallel first and second arms and a slot running between the arms, an aperture in the first arm substantially perpendicular to the slot and located towards the outer end of the arm, the aperture shaped to receive and hold a stationary tool in use, a groove formed between the outer end and inner side of the first arm, the groove passing through the underside of the outer arm to the aperture;

the tool comprising a body mutually shaped with the aperture so that the tool is received and held in place by a close fit between the tool and tool block so that in use the tool remains in position and does not move at least when aligned horizontally;

the groove sized and shaped so that at least a portion of the body of the tool can pass through the groove. Preferably the tool block has at least one grub screw hole on the first arm, passing from the outside through to the first arm aperture the grub screw hole threaded to receive a grub screw to hold the tool in position.

Preferably the tool block has at least one grub screw hole on each side of the arm. Preferably the grub screw hole or holes are aligned perpendicular to the aperture and the body of the tool block. Preferably the first arm aperture and the groove are particularly shaped and sized to receive and hold in position a dimpling die tool.

Preferably the first arm aperture passes fully through the arm to have an open outer end.

Preferably the second arm has an aperture having a common axis with the aperture in the first arm, the second arm aperture adapted to receive a die punch and associated actuator in use. In a second aspect, the invention may broadly be said to consist in a tool block for holding a tool, comprising:

a substantially u-shaped body having substantially parallel first and second arms, with a slot running between the arms;

an aperture in the first arm, substantially perpendicular to the slot and located towards the outer end of the arm, the aperture shaped to receive and hold a stationary tool in use,

the tool block having at least one grub screw hole on the first arm, passing from the outside through to the first arm aperture, threaded to receive a grub screw.

Preferably the at least one grub screw hole is aligned perpendicular to the aperture and the body of the tool block.

Preferably the tool block has at least one grub screw hole on each side of the arm. Preferably the tool block has a groove formed between the outer end and inner side of the first arm, the groove passing through the underside of the outer arm to the aperture.

Preferably the first arm aperture passes fully through the arm to have an open outer end.

Preferably the first arm aperture and the groove are particularly shaped and sized to receive and hold in position a dimpling die tool.

Preferably the second arm has an aperture having a common axis with the aperture in the first arm, the second arm aperture adapted to receive a die punch and associated actuator in use.

In a third aspect, the invention may broadly be said to consist in a dimpling die punch, comprising:

a punch body having a first end and a second end, a depression formed in the punch body at the second end, and a passage formed into the base of the depression, the passage extending fully through the main body, a hole punch, formed separately and sized to locate into the passage, the passage and hole punch formed so that the tip of the hole punch extends outwards from the base of the depression no further than the perimeter of the depression.

Preferably the passage is wider at the first end than at the second end, the first end of the hole punch sized to fit the wider passage portion, the second end of the hole punch sized to fit the narrower second end so that when the hole punch is in position in the passage, the tip extends from the second end. Preferably the punch body has a flange at the second end which gives the punch body t-shaped cross section.

Preferably the perimeter of the depression is formed and sized so that the depression extends outwards into the flange.

Preferably the wider passage portion is at least partly threaded, the die punch also having a grub screw sized to fit and screw into the wider passage portion.

Preferably the punch body and flange are substantial ly cylindrical, the centre of the passage on the axis of rotation.

Preferably the punch body has a circumferential notch formed in the body behind the flange.

Preferably the circumferential notch is formed with a first side towards the first end and a second side towards the second end, the first side formed at a shallow angle relative to the axis of rotation and in comparison with the second side.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a perspective view looking upwards from underneath of a preferred embodiment of tool block which in use is connected to a rollforming machine, and which holds the stationary dimpling die punch of the preferred embodiment of the present invention, the tool block having the shape of an inverted 'u', a groove for removing or replacing the stationary dimpling die punch shown on the end or base of the outer arm of the inverted V;

Figure 2 shows an exploded perspective view of the tool block and associated items, with the dimpling die punch of the present invention, a separate second die part and a hydraulic actuator also shown;

Figure 3a shows a cutaway side view of the tool block of figures 1 and 2, connected to and forming part of a rollforming machine, the dimpling die punch shown in position on the outer arm of the tool block, the second die part shown connected to the end of the hydraulic actuator on the inner arm of the tool block to force the second die against the stationary dimpling die punch in use, the groove for locating the dimpling die punch on the tool block shown on the lower end of the outer arm of the tool block;

Figure 3b shows the arrangement of figure 3a, with the dimpling die punch shown removed from the tool block, and a hole for a grub screw to hold the dimpling die punch in position in use shown aligned horizontally and perpendicular to the axis of operation of the second die as it moves against the stationary dimpling die punch; and

Figure 4 shows a cutaway side view of the dimpling die punch subassembly, the subassembly composed of a generally cyl indrical punch body with a circular flange at one end so that the punch body is generally t-shaped in cross-section, a dish depression formed on the flanged end face and the punch body having a central axial passage that extends through the body, a hole punch located in the central passage, one end of the hole punch extending outwardly from the base of the dish depression, the punch held in place by a grub screw threaded into the passage at the other end from the dish depression.

DETAILED DESCRIPTION OF THE INVENTION The dimpling die punch and tool block of the present invention are intended for use primarily but not exclusively with rollforming machines. In rollforming operations, sheet metal is fed into one end of a rollforming machine and undergoes a series of sequential operations (e.g. bending between rollers) at different stations to produce the finished product at the other end. Figure 1 shows a tool block 1 that forms part of one such station.

The tool block 1 has a slot 2 in the lower edge, so that from the side the tool block 1 has the form of an 'n' or an inverted 'u'. The tool block 1 is connected to and forms part of the overall rollforming machine. In use, one side edge of the metal sheet to be formed slots into the slot 2, the side edge moving linearly through the slot during forming operations. The tool block 1 holds a tool set such as a die punch pair - e.g. the stationary dimpling die punch 3 of the preferred embodiment of the present invention, and a separate second die part 4, one of each in each of the arms of the 'u'. In the embodiment shown, a dimpling die punch 3 is held stationary in the outer arm of the tool block (the outer arm being the left-hand arm in figure 1) and the associated second die part 4 is connected to the end of a hydraulic actuator 5, on the other (inner) arm. An exploded view, showing the tool block 1 , the stationary dimpling die punch 3, the second die part 4 and the hydraulic actuator 5, is shown in Figure 2, along with items to connect the various elements, such as swash plates, washers, and bolts, used for assembly. In use, the second die part 4 and actuator 5 cycle between an initial position where the die part 4 is held away from the stationary dimpling die punch 3, and a closed position where the hydraulic actuator acts to move the second die part 4 from the initial position to force the second die part 4 against the stationary dimpling die punch 3. When this operation is performed with a sheet of metal between the stationary dimpling die punch 3 and the second die part 4, is deformed, or pierced/punched, or both at once, depending on the tools used. Using the dimpling die punch 3 and second die part 4 of the preferred embodiments, the single operation both deforms and pierces the sheet to create a dimple suitable for holding a countersunk screw or rivet head, and also a central hole in the bottom of the dimple through which the shaft of a screw or rivet can pass. On completion of the operation, the hydraulic actuator 5 cycles the second die part 4 back to the initial position, ready to repeat.

A cutaway side view of the tool block 1 , dimpling die punch 3, second die part 4, and hydraulic actuator 5 is shown in figures 3a and 3b. An aperture 6 runs through the tool block 1. The aperture 6 is aligned perpendicular to the slot 2, which divides the aperture into a stationary die side 6a or outer side (through the outer arm) and a moving die side 6b or inner side (through the inner arm). Although the apertures 6a and 6b are separate and on separate arms of the tool block 1 , they can be considered together as they have a common axis, along which the moving die moves to contact the dimpling die 3. As shown in Figure 3a, in the preferred embodiment the dimpling die punch locates in use into the stationary die side 6a of the aperture 6, opposite the second die part 4 and hydraulic actuator 5 which are located in the moving die side aperture 6b. The dimpling die punch 3 is, in the preferred embodiment, held in place by a close fit between the dimpling die punch 3 and the walls of the tool block 1 - that is, the dimpling die punch and tool block are mutually machined to fit closely together. Although as described above the apertures 6a and 6b are open at either end on the arms, in alternative embodiments one or both of the apertures 6a and 6b could be closed at their outer ends.

In the preferred embodiment (i.e. with at least the outer end of the aperture 6a open), the dimpling die punch 3 can be removed from the tool block 1 by applying pressure through the outer end of the aperture 6a so that the dimpling die punch 3 drops out of the inner end of the aperture 6a. This removal and replacement operation will now be described in further detail.

With reference to figure 1 , a groove 7 is shown on the underside of the outer arm of the 'u' of the tool block 1 . To fit the dimpling die punch 3 to the tool block 1 , the axial body of the dimpling die punch 3 is aligned with the axis of the aperture 6a, under the base and aligned with the groove 7. The dimpling die punch is then moved upwards, through the groove 7 until the body of the dimpling die 3 is aligned with the aperture 6a. The dimpling die punch 3 is then pressed backwards into the inner end of the aperture 6a, and is held in place by the close fit between the dimpling die punch and the tool block 1 . As shown on Figure 1 and figure 3b, the preferred embodiment includes holes 18 on both sides of the tool block 1 , aligned horizontally and perpendicular to the axis of operation of the second die. The holes 18 are threaded to receive a grub screw which is tightened down on to the sides of the dimpling die punch 3 to hold it in position in use.

In operation, the second die part 4 is repeatedly forced against the outer part of the dimpling die punch 3. As outlined above, the die punch and tool block are mutually shaped so that the die punch remains in position and does not move relative to the tool block as it is repeatedly struck in use. To remove the dimpling die punch 3 from the tool block 1 , as shown in figure 3b, pressure (either constant or a series of blows or strikes) is applied to the outer end of the dimpling die punch 3 so that it moves forward and drops down to be removed through the groove 7. If the aperture 6a is closed at the outer end, then the structure of the die punch 3, or the aperture 6a, or the slot 7 (or some combination thereof) can be adapted so that a tool can be inserted to lever the die punch 3 out, rather than by exerting pressure on the outer end. This arrangement ensures that items on the inner arm of the tool block 1 do not need to be disassembled in order to allow the dimpling die punch 3 to be removed or replaced.

The structure of the dimpling die punch 3 will now be described with particular reference to figures 2 and 4. The dimpling die punch 3 has a main punch body 8, with a first end 9 and a second end 10. The second end in use fits into the inner end of the tool block aperture 6a. A cut-out or depression 1 1 is formed in the punch body 8 at the second end. A hole punch tool 12 is located in the depression so that the tip 13 of the hole punch tool 12 extends perpendicularly outwards from the base of the depression 1 1 . As the tip 1 3 extends from the base of the depression, a dimpling operation and a hole punch operation can be performed simultaneously when the second moving die is forced against the dimpling die punch. Usually the second moving die will have a cutout or aperture which is sized with and aligned with the tip 13 so that the tip 13 can punch cleanly through the sheet to form a hole.

In the preferred embodiment, the main body 8 and the hole punch 12 are formed as two separate items. The main body 8 has a passage 14 which is formed into the base of the depression 1 1 . The hole punch 12 locates into this passage, the body of the hole punch 12 and the passage 14 sized so that the punch 12 fits snugly into the passage 14, with the tip 13 extending outwards from the base of the depression 1 1 . The preferred embodiment of hole punch 12 is formed from a solid piece of metal so that it can withstand the striking forces it experiences in use. The passage 14 in the preferred embodiment extends fully through the main body 8, the passage 14 wider at the first end 9 than at the second end 10, the first end of the hole punch 12 sized to fit the wider passage portion, the second end of the hole punch 12 sized to fit the narrower second end of the passage 14 so that when the hole punch 12 is in position in the passage 14, the tip 13 extends from the second end 10. In the most preferred embodiment, the wider passage portion is at least partly threaded. To assemble the dimpling die punch 3, the hole punch 12 is passed into the passage 14, narrow portion first. A grub screw 16 is then screwed into the threaded portion to press on the inner end of the hole punch 12 (the wider portion) and hold the hole punch 12 in place. It is preferred that the outer end of the hole punch is mutually chamfered with the junction between the wider and narrower passage portions. This allows progressive force to be applied to the hole punch to hold it in position as the grub screw 16 is tightened onto the hole punch 12. Alternatively, the passage could be closed at the outer end, with the hole punch and hole sized so that when the hole punch is inserted into the open end, the tip extends from the passage, the base of the hole punch resting against the base of the passage. As another alternative, the hole punch could pass through a passage open at both ends, the hole punch held in position relative to the passage by any one of a number of suitable techniques, such as threading the hole punch and passage, shaping the passage and hole punch to have a mutual chamfer or similar shape which holds the punch in position, etc. Alternatively the dimpling die could be formed as a unitary, solid item.

It is most preferred that the punch body 8 has a flange 1 5 at the second end so that the punch body 8 has an overall t-shape when viewed from one side. It is also most preferred that the perimeter of the depression 1 1 is such that the depression 1 1 extends outwards into the flange 15. In the most preferred embodiment, the punch body 8 and flange 15 are substantially cylindrical in overall appearance, with a central axis of rotation, the passage also circular in end view and aligned on the axis of rotation of the flange 1 5 and punch body 8.

In the preferred embodiment, the punch body 8 has a circumferential notch 17 formed in the body 8, slightly behind the flange 15. The preferred embodiment of circumferential notch 1 7 is formed with a first side towards the first end and a second side towards the second end, the first side formed at a shallow angle relative to the axis of rotation and in comparison with the second side. The inner ends of grub screws passed through the holes 18 pass into the circumferential notch 1 7 to assist in holding the dimpling die in position.

In the arrangement described above, the dimpling die punch has been described as the stationary element of the die punch pair. The arrangement described above could be reversed, so that the dimpling die punch is connected to a hydraulic actuator or similar to move against a stationary second die part. The dimpling die punch 3 has also been described as formed from three separate items: the body 8, the hole punch 12, and the grub screw 16. This arrangement allows any damaged piece to be replaced easily. However, the dimpling die punch 3 could be formed as a unitary solid item if required, the hole punch and punch body formed as a single solid item.

In the most preferred embodiment, the tool block 1 will be particularly adapted to receive a particular tool, such as for example the dimpling die punch 3. The groove 7 and aperture 6a will be sized and shaped internally to allow the dimpling die punch 3 to be positioned where required and then held in position. For example the inner end of the aperture 6a will be shaped to receive the flange 15, or will have a complimentary recess 19 sized and shaped to receive the flange 18, as shown in figure 3b.

The groove arrangement in the tool block 1 , and the insertion and removal methods described above, ensure that tools such as the second die part 4 and the actuator 5 located on the inner arm of the tool block 1 do not need to be disassembled in order to allow the dimpling die punch 3 to be removed or replaced. This results in ease of replacement of a relatively easily damaged component, leading to greatly reduced downtime and therefore increased productivity.