METHOD AND DEVICE FOR MOVING A TOOL TO EXACT SHAPING AND WORKING ENGAGEMENT WITH A STRIP OF MATERIAL HAVING A REPEATED BASIC SHAPE

Abstract: Method and device for moving a tool (8) to a desired posi­ tion relative to and in engagement with an incrementally advanced strip of material (10) held in place during the work stroke of the tool and having a repeated basic shape. Between the advancements, the strip (10) is held longitu­ dinally stationary, so that the tool can be engaged by a movement across the strip, without moving it therealong. The tool is finely adjusted relative to the basic shape by a movement to the correct engagement position steered by at least one basic shape sensor (36) connected to and spa­ ced from the tool along the strip. To control the tool, the basic shape sensor is caused to locate the exact posi­ tion of one (48) basic shape at one or more basic shape spacings from the basic shape (50) to be engaged by the tool (8). The sensor brings with it and steers the tool As it moves to locate the exact position, the sensor brings with it and steers the tool. The work stroke of the tool perpendicular to the strip is triggered only when the sen­ sor has reached said exact position. The device comprises a tool bed (2) with die means (42,44), a slide (4) slide­ ably mounted on the bed with a tool holder (2) carrying the tool spaced from the die means. Between the tool and the die means there is a space for incremental advance of the strip. The tool holder (20) carries the basic shape sensor (36) which is mounted spaced from the tool and locates the exact position of said basic shape (48) spaced from the basic shape (50) to be engaged by the tool. The tool is finely adjusted relative to said basic shape by the position locating movement of the sensor bringing the tool with it along the length of the strip.

Description: The present invention relates firstly to a method of bringing a tool to a desired engagement position relative to and in engagement with a strip of material which is intermittently advanced in its longitudinal direction past the tool and which has a repeating basic shape, for example in the form of linked, identical products shaped in the strip of material, which cyclically repeat in the longitudinal direction of the strip. The basic shape can be, for example, a plurality of linked identical products made in the strip. Secondly, the invention relates to a tool positioning device whereby a tool can be brought to a desired engagement position relative to and in engagement with an incrementally advancable strip of material which is held stationary during the forming or working engagement of the tool and has a cyclically repeating basic shape. Document US-A-3 961 512 forms the base for the preambles of claims 1 and 3. In various fields of manufacture there is a need to efficiently produce a large number of identical products of a certain predetermined shape (cross-sectional shape), said products being linked to each other, for example side by side, and forming a long strip of material; or in other words a strip incorporating the products. One example of such manufacture is the production of so-called sheet nails in strips, i.e. nails made of profiled sheet metal being parallel to each other and linked via connecting bridges between the longitudinal edges of adjacent nails in the strip. In such a sheet nail strip, the individual nails (= the products) are made with a certain desired profile shape as viewed in cross-section. The nails can be V-shaped in cross-section, for example. Examples of such sheet nails are revealed in Swedish Patent Application 8504557-3. In producing linked products in strips with a certain desired final shape of the individual products, the strip (which can be a sheet metal strip for example) is worked and/or shaped sequentially in a number of tool stations arranged in sequence in the direction of movement of the strip. It is for example possible to produce the basic shape of the product in a first tool station with the aid of a vertically acting shaping punch (i.e. a bending punch) which is repeatedly brought into shaping engagement with the simultaneously incrementally advanced sheet metal strip, so that it is given the repeated basic shape, i.e. a V-shape. In the following additional working and shaping stations located downline from the first mentioned station in the advancing path of the strip, the products included in the strip can be given a successively more finished shape. Even if the basic shape of the product in question (which is intended to be produced at a first station) is made with the greatest possible precision and regularity, to among other things, achieve a constant spacing between the products in the strip, it is still not possible in practice to avoid a certain lack of precision in the regular shaping and spacing of the products in the strip. This can be because of variations in the working cycle of the first shaping punch (the bending punch), variations in the incremental advancing of the strip between the basic shaping of two adjacent products in the strip, varying material properties in different portions of the strip, etc. If the following tool stations located downline in the direction of advance of the strip are placed at entirely fixed stationary locations spaced along the strip path, it is not possible to guarantee that the workings or shapings made at these stations will be superimposed on the shape (of the respective product in the strip) already produced upline at the exact intended location of each product. Thus the tool at the downstrem workstation in question will at times make its shaping or working stroke at a somewhat misplaced location on the product. The actual tool engagement location will thus often lie somewhat laterally displaced in relation to the exact desired location on the product where the tool should have struck. The reason is that the individual product as a result of the above mentioned variations is not exactly in the position which it would assume if each such variation could be avoided, and this is impossible in practice. The problem on which the invention is based is thus assuring entirely correct positioning of the tools at the workstations located downline, relative to the basic shapes of the products already produced upline, which shapes have now reached the downline workstation in question where continued shaping or working is to take place. This correct positioning of the tool in question relative to the previously made basic shape in the strip should be able to be achieved regardless of whether there occurs a certain spacing variation or basic shape variation along the strip. The basic idea of the present invention is thus to solve said problem by the downline workstations having a somewaht "floating striking position" in relation to the strip which is stationary immediately prior to and during the shaping or working engagement by each tool. Within the limits of this floating striking position, there can be an automatic correction and adaptive fine adjustment of the tool, so that the tool actually assumes the exact intended engagement position relative to the product in the strip, which is now to be subjected to continued forming or working with the tool in question. As to the method of the present invention, said problem is solved by the teaching contained in claim 1. Furthermore, as to the tool positioning device of the present invention, said problem is solved by the teaching contained in claim 3. In summary the basic principle of the invention can be said to be that the tool "floatingly" arranged in the direction of advance of the strip seeks out its correct engagement position (i.e. adjusts its own position relative to the actual positions of the basic shapes in the strip) by indexing (with the aid of each respective basic shape sensor) on a basic shape (a product) in the strip, lying somewhat downline or upline from the basic shape in the strip which the tool is to go into shaping or working engagement with. Furthermore, the slide unit is preferably slideably mounted on the tool bed parallel to the advancing direction of the strip of material, there being arranged between the bed and the slide biasing means which strive to return the slide to a balanced starting position when the slide has been displaced therefrom. The biasing means, within the displacement range of the slide, serve to return the slide to a balanced starting position before the subsequent indexing of the tool on the next basic shape (product) as the strip advances. The die means are suitably mounted on the slide, and the tool holder suitably comprises a column mounting, which also supports the basic shape sensor, which is arranged in alignment with, preferably directly above, a counter element arranged on the slide, the sensor and the counter element being on opposite sides of the space for the material strip. The basic shape sensor can comprise a shape locating means which is displaceable by biasing means arranged in the column mounting to an extended position, where the locating means can be pressed in against the force of the biasing means, said locating means having a configuration corresponding to the basic shape at its end facing the strip space, the counter element also having a configuration conforming to the basic shape, said configuration being complementary to the configuration of the locating means. In the indexing movement of the locating means seeking the exact position the locating means and the counter element are moved through their respective configuration, from opposite directions to engagement with the basic shape at its deepest point, thus achieving the desired fine adjustment of the locating means and thus the tool relative to the respective basic shape. In order to simplify the design and improve the reliability of the device, the column mounting can suitably comprise two parallel, spaced columns, the lower ends of which are fixed to the slide and the upper ends of which are received in a platform, which extends transversely over the slide slideable in the tool bed. Both the basic shape sensors and the tool extend downwardly from the underside of the platform, towards cooperating die means arranged on the top of the slide. A preferred embodiment of the method and device according to the invention will now be described in more detail below with reference to an illustrative example shown in the accompanying drawing. Figure 1 shows in partial section an elevation of a device according to the invention and Figure 2 shows a plan view of the device of Figure 1. The device shown in the drawings is intended to provide exact indexing of a tool relative to a basic shape or a product which is included in a strip of material and which is to be subjected to supplementary forming or working with the aid of the tool. The tool is to be moved into engagement with the basic shape in question (the product) which is in the vicinity of the workpoint of the tool. During the shaping or working engagement of the tool with the strip portion in question, the strip is held longitudinally stationary, but after the work stroke of the tool has been completed, the tool is disengaged from the strip, which is then advanced one basic form spacing, so that the next adjacent basic form (product) in the strip can be subjected to the same shaping or working, by the tool performing a new work stroke etc. The drawing shows a device according to the invention which comprises a horizontally mounted tool bed 2 which supports a slide 4 which is slideably mounted on the bed and is guided longitudinally to the bed by means of a pair of fixed guide rails 6 at the sides of the bed. The slide is slideable on the bed parallel to the direction of movement of the strip of material to be subjected to forming or working by means of the tool, which is exemplified in the drawing by a vertically operating punch 8. The strip is generally designated 10, and is shown in the drawing as a band which upline from the device has already been imparted a repeating V-shape at a bending station for example. Between the bed 2 and the slide 4 are four spring means 12, each consisting of a sleeve 14 fixed to the bed and in which there slides the head of a bolt 16 screwed into the slide 4. A helical spring 18 is arranged around the sleeve and the bolt and works between the slide and the bed 2. The spring means 12 serve to return the slide 4 to a balanced starting position after the completed stroke of the tool 8 after the fine adjustment of the tool achieved by the device is released as the strip 10 is advanced one step, whereafter there is another fine adjustment of the tool, a new work stroke and so on. On the slide 4 there is mounted a tool holder in the form of a column mounting 20 comprising two vertical columns 22, 23, the lower ends of which are fixed to the slide and the upper ends of which are received in bores 24 in a platform 26 extending transversely above the slide 4, and spaced above the same. The platform 26 is held in the position shown on the columns by means of a centrally placed carrier rod 28 extending from above, which has a circumferential indentation or groove 30, in which there is received the flagne 32 of a holder 34 screwed into the top of the platform. The platform 26 of the column mounting supports a downwardly directed basic form sensor 36 in the form of a downwardly extending shape locator mounted in a bore 38 in the platform 26 and kept extended to its lowermost position by a compression spring 40 in the bore 38. Directly beneath the tool 8 there is a die 42, in this case in the shape of an upwardly directed die edge mounted on the slide 4. Directly under the sensor 36 there is another die 44, in this case a counter element for the sensor, said die also being fixed to the top of the slide 4. Between on one side tool 8 and the sensor 36 and on the other side the dies 42, 44 there is, as can be seen, a horizontal space for the strip of material 10. In order to be able to index the laterally adjustable tool 8 relative to the basic shapes in the strip, i.e. in this case relative to the V-shaped, side-by-side linked products in the strip 10, both the lower portion 46 of the sensor 36 and the top of the counter element 44 have configurations conforming to the basic shape, which are mutually complementary and make it possible to press a V-shaped section of the strip between them. In the very schematic example shown, the fine adjustment of the tool relative to the respective V-shape in the strip 10 is accomplished by indexing on a V-shape 48 located three spaces downline from the V-shape 50 into which the tool 8 is to be engaged. The drawing shows with solid lines the slide and the column mounting with the tool and sensor when these components are in their rest position prior to fine adjustment of the tool by indexing by means of the sensor. The dash-dot lines show said components after indexing of the tool. The sensor is moved downwards to complete shape engagement with the V-shape 48 at its deepest point, and this means that the sensor 36 and the counter element 44 must be displaced a distance δ to the right in Fig. 1. The strip 10 is shown with dash-dot lines when this exact engagement has been achieved. The downward movement of the sensor 36 is achieved by lowering the platform 26 on the columns 22, 23, and this is effected by importing a downward movement to the carrier rod 28. When the exact shape engagement between the sensor 36, the strip 10 and the counter element 44 has been achieved, thus completing the fine adjustment, the lowering of the platform 26 continues and the sensor 36 is pressed into the bore 38 against the force of the spring 40. The downwardly directed movement can suitably be accelerated, so that the required striking velocity of the tool 8 is reached when its point engages the bottom of the V-shape 50 which has then been pressed against the die 42, so that the desired tool effect is achieved. In the example shown it is desired to achieve a partial separation of adjacent products in the strip of material. In this case, it means producing sheet nails with cross-sectional upside down V-shape, where adjacent nails in the strip are linked to each other via residual bridges (between the longitudinal edges of the nails) at the bottoms of V-shapes 48, 52, 54, 50 etc.

Claims: Method of bringing a tool (8) to a desired engagement position relative to and in engagement with a strip of material (10) which is intermittently advanced in its longitudinal direction past the tool and which has a repeating basic shape, for example in the form of linked, identical products shaped in the strip of material, which cyclically repeat in the longitudinal direction of the strip, characterized in that between the intermittent advances, the strip (10) is held stationary in its longitudinal direction, so that the shaping or working engagement of the tool (8) with the strip can take place through a movement perpendicular to the longitudinal direction of the strip, without moving the tool in the longitudinal direction of the strip; that the tool is finely adjusted relative to the basic shape in the strip by being moved to the correct engagement position controlled by at least one basic shape sensor (36) connected to the tool, said sensor (36) being spaced a predetermined number of repeating basic shapes from the basic shape which the tool (8) is to engage, as viewed in the longitudinal direction of the strip; and that the control of the tool (8) by the basic shape sensor (36) is achieved by the sensor (36) being made to locate in a mechanical way the exact position of one (48) of the cyclically repeated basic shapes in the strip, located one or more basic shape spacings from the basic shape (50) which the tool (8) is to be brought into engagement with, said tool being brought with and steered by the sensor (36) during its precision locating movement in the longitudinal direction of the strip; and that the shaping and working movement of the tool (8) perpendicular to the strip is only triggered when the sensor (36) has reached said exact position, the tool (8) and the basic shape sensor (36) cooperating with opposite first and second die means (4,44), respectively. Method according to Claim 1, characterized in that the fine adjustment of the tool (8) relative to the basic shape in the strip (10) is controlled by at least two basic shape sensors (36) connected to the tool (8), at least one of which is disposed upline (before) and another downline of (after) the tool (8), relative to the advance of the strip (10). Tool positioning device, whereby a tool (8) can be brought to a desired engagement position relative to and in engagement with an incrementally advancable strip (10) of material which is held stationary during the forming or working engagement of the tool and has a cyclically repeating basic shape, for example by the strip consisting of linked identical products, forming together the strip, characterized in that the device comprises a tool bed (2) with die means (42,44) thereon, a slide (4) supported by the bed and being movable, parallel to the advancing direction of the strip of material, relative to the bed, on which slide there is arranged a tool holder (20) which supports the tool (8) at a distance from a first cooperating die means (42) being disposed opposite the tool, there being provided between the tool and said die means (42) a space for the strip of material through which the strip (10) can be moved by increments, and that the tool holder (20) also carries at least one basic shape sensor (36) which is spaced a predetermined number of repeating basic shapes from the basic shape which the tool is to engage, and is disposed to locate the exact position in the strip of a basic shape (48) spaced from the basic shape (50) which the tool is to engage, and a second cooperating die means (44) being disposed opposite the basic shape sensor (36), fine adjustment of the tool relative to said basic shape being effected by the sensor bringing with it the tool in its precision locating movement along the strip. Device according to Claim 3, characterized in that the slide (4) is slideable on the tool bed (2) and that between the bed and the slide there are biasing means (12) which strive to return the slide to a balanced starting position when the slide has been displaced therefrom. Device according to Claim 3 or 4, characterized in that die means (42,44) are mounted on the slide, and that the tool holder (20) comprises a column mounting (22,23,26) which also carries the basic shape sensor (36) which is arranged opposite, preferably directly above, a counter element (44) mounted on the slide (4), the sensor and the counter element being on opposite sides of the space for the strip of material. Device according to Claim 5, characterized in that the basic shape sensor (36) comprises a shape locating means which is displaceable by biasing means (40) arranged in the column mounting (22,23,26) to an extended position, where the locating means can be pressed in against the force of the biasing means, said locating means (36) having a configuration corresponding to the basic shape at its end (46) facing the strip space, and that the counter element (44) also has a configuration conforming to the basic shape, said configuration being complementary to the configuration of the locating means. Device according to Claim 5 or 6, characterized in that the column mounting comprises two parallel, spaced columns (22,23), the lower ends of which are fixed to the slide (4) and the upper ends of which are received in a platform (26), which extends transversely over the slide slideable in the tool bed, and that both the basic shape sensor (36) and the tool (8) extend downwardly from the underside of the platform, towards cooperating die means (42,44) arranged on the top of the slide. Device according to any of Claims 3-7, characterized in that the tool holder (20) carries two or more basic shape sensors (36) arranged on opposite sides of the tool (8) and/or material strip (10).

Inventors: SJOEGREN, BOERJE, SJÖGREN, Börje
Applicants: NORDISK KARTRO AB
Application year: 1987
Main classification: B21D53
IPC codes: B21D53, B21D43, B21D13, B21D28, B23Q16