METHOD FOR THE MANUFACTURE OF RIVET FOR A FIXED SPIKE OR FOR A SLEEVE-MOUNTED SPIKE, RESPECTIVELY, AND EQUIPMENT FOR CARRYING OUT THE METHOD

Abstract: The invention concerns a method for the manufacture of a rivet for a fixed spike or for a sleeve-mounted spike, respectively, by pressing in a mould. In the method of the invention, the cavity space in the mould (10, 20), corresponding to the shape of the spike to be manufactured, is first filled to the desired extent with a first material (1) to form the body part of the spike. Hereupon a first punch (30), whose diameter is substantially smaller than the diameter of the cavity space in the mould, is fitted into the cavity space concentrically with the cavity space, and the annular space between said first punch (30) and the cavity space is filled with a second material (20) so as to form the wear-resistant surface layer for the spike. Next, the first punch (30) is removed, and the space remaining after said punch is filled with a third material. Ultimately the spike is pressed to the desired shape and density, whereinafter the spike is removed from the mould. The invention also concerns equipment for carrying out the method.

Description: ■ J Method for the manufacture of rivet for a fixed spike or for a sleeve-mounted spike, respectively, and equipment for carrying out the method The invention concerns a method for the manufacture of a rivet for a fixed spike or for a sleeve-mounted spike, respectively, by pressing in a mould. 0 The invention further concerns equipment for carrying out the method for the manufacture of a rivet for a fixed spike or for a sleeve- mounted spike, respectively, said equipment comprising a mould pro¬ vided with a cavity space, pressing equipment, and filling equipment. 5 The commonest solution in the prior-art fixed spikes and in the rivet parts of sleeve-mounted spikes, respectively, is such that the fixed spike or the rivet part of a sleeve-mounted spike, respectively, is provided with a separate hard-metal tip. Such a spike is usually Q manufactured in a mould consisting of several parts, so that the mould parts are provided with punches acting in the axial direction of the spike to be manufactured, the spike blank being pressed axially in opposite directions by means of said punches. It is a drawback of such methods of manufacture and equipment that they require several c separate working steps and, moreover, the construction of the equip¬ ment and of the moulds is complicated. The object of the present invention is to provide an improvement over the prior art methods of manufacture and equipment. A more specific object of the invention is to provide a method of manufacture and an equipment intended for Q carrying out the method which are intended in particular for the manufacture of such a large-tip spike wherein the wear-resistant layer to be formed in the tip portion of the rivet is formed as an annular part around the tip. Such a spike has been described earlier in the FI Patent Application No. 880294. In view of achieving the objectives stated above and those that will come out in the following, the method in accordance with the invention 1 is mainly characterized in that the method comprises the following steps: the cavity space in the mould, corresponding to the shape of the c spike to be manufactured, is filled to the desired extent with a first material to form the body part of the spike, a first punch, whose diameter is substantially smaller than the diameter of the cavity space in the mould, is fitted into the cavity ■JO space concentrically with the cavity space, and the annular space between said first punch and the cavity space is filled with a second material so as to form the wear-resistant surface layer for the spike, the first punch is removed, and the space remaining after said punch ■J is filled with a third material, and the spike is pressed to the desired shape and density, whereinafter the spike is removed from the mould. 20 On the other hand, the equipment in accordance with the invention is mainly characterized in that the mould is formed as a two-part mould, so that the counter-faces of the first mould and of the second mould, to be placed one against the other, are placed in the widest portion of the cavity space in the mould in the area of the foot widenings 25 of the cavity space and that the press equipment comprises punches, which are fitted to act towards the second mould substantially per¬ pendicularly to the counter-faces. Compared with the prior-art solutions, by means of the invention 30 several advantages are obtained, whereof, e.g., the following may be stated. In the method in accordance with the invention, by pressing from one direction, it is possible to manufacture the hard tip part as well as the round forms in the foot part of the spike, the latter being of essential importance for the conduct of the spike in a 35 tyre. In the method and equipment in accordance with the invention, the wear-resistant outer face of the spike tip may be formed as of desired thickness. If necessary, said wear-resistant outer face may ■ j be composed of several different materials. Since, in the method of the invention, the spike is manufactured in the mould by pressing from one direction, the tip portion of the spike is compressed more densely than the foot part. Since the foot part of the spike remains c less dense than the tip, a spike of lower weight and lower consumption of material are obtained. A remarkable advantage of the equipment is simplicity of the mould solution, by means of which, however, the foot part of the spike, placed against the rubber, can be shaped freely. Moreover, the method of manufacture in accordance with the • j Q invention can be automated very easily. In the following, the invention will be described by way of example with reference to the figures in the accompanying drawing, the inven¬ tion being, however, in no way strictly confined to the exemplifying ■| embodiment illustrated in same. Figures 1 to 7 in the accompanying drawing are sectional views of a preferred equipment used in the method of manufacture in accordance with the invention in the different steps of the method. 0 The equipment for the manufacture of a spike, shown in the figures in the drawing, comprises a two-part mould, which comprises a first mould 10 and a second mould 20 to be fitted one against the other. Into the first mould 10 a through hole 11 has been formed for the 5 body part and the tip of the spike to be manufactured. Into the hole 11 a first foot widening 12 has been formed for the foot of the spike in the area of the counter-face of the first mould 10 to be fitted against the second mould 20. In a corresponding way, into the second mould 20, a second foot widening 21 has been formed in the area of 0 the counter-face 22 of the second mould 20. The equipment in accord¬ ance with the invention further includes a press device, which com¬ prises a first and a second punch 30 and 40, by means of which the powdery materials of manufacture of the spike are pressed in the mould 10,20 to the shape required by the mould and to the desired 5 density. The equipment in accordance with the invention further comprises a filling equipment for filling the mould with the materials of manufacture of the spike. Said filling equipment is, however, not 1 shown in the figures in the drawing. The filling equipment may com¬ prise, e.g., a suitable dosage funnel and related dosage means for filling the mould. c In Fig. 1 in the drawing, the first step of the method of the inven¬ tion is shown. In the step shown in Fig. 1 the first mould 10 and the second mould 20 have been fitted one against the other by their counter-faces 13 and 22 so that the foot widenings 12 and 21 in the moulds 10,20 are placed facing each other. In the first step of the •JQ method of manufacture, shown in Fig. 1, the mould 10,20 is filled with a first material 1, of which the body part and the flange of the spike to be manufactured are composed. Fig. 2 shows the second and the third step. In the second step of -J5 the method of manufacture, a first punch 30 is fitted into the hole 11 provided in the first mould 10, by means of which said punch 30 the first material 1 of the spike, fitted into the mould in the first step, is pressed towards the second mould 20 so that filling of the mould is also guaranteed in the areas of the foot widenings 12 and 20 21. The diameter of the first punch 30 is smaller than the diameter of the hole 11, so that an annular space remains in the hole 11 around the first punch 30. In the third step of the method of manu¬ facture, said annular space is filled with a second material 2 while the first punch 30 is in the hole 11 in the position shown in Fig. 25 2. Out of said second material 2, the annular wear-resistant part to be provided at the tip of the spike is formed. The fourth step of the method of manufacture is shown in Fig. 3. In this step of the method the second punch 40, which is placed on the 30 first punch and is coaxial with the first punch 30, is fitted into the hole 11 provided in the first mould, said second punch moving in the same direction with the first punch 30. In the fourth step of the method of manufacture, shown in Fig. 3, an intermediate pressing of the spike blank is carried out by means of both of the punches 35 30,40 at the same time. On completion of said intermediate pressing the fifth step of the method of manufacture is reached, which is shown .in Fig. 4. In this step the first punch 30, placed inside the second 1 punch 40, is pulled out of the mould, and the mould is filled with a third material 3 while the second punch 40 is still in its position in the position shown in Fig. 4. Thus, by means of the third material 3, the space that remains inside the second material 2 and the second punch 40 is filled to the desired extent. Upon completion of the filling with the third material 3 the sixth step of the method of manufacture is reached, which is shown in Figures 5 and 6 and in which the pressing of the materials 1,2,3 to ■jQ the desired density is carried out. This is performed so that first the third material 3 is pressed by means of the first punch 30. Both of the punches 30,40 may reach the same level, as is shown in Fig. 5, but this is in no way necessary. Hereinafter the ultimate pressing of the spike is carried out by means of both of the punches •J5 30,40 at the same time in the way shown in Fig. 6, whereby the spike obtains its ultimate shape and density. It may be considered an alternative embodiment for this step of the manufacture that, after the first and the second punch 30,40 have been pressed to the same level, said punches 30,40 are removed and a single Dunch is fitted 0 in their place, whose diameter corresponds to the diameter of the second punch. The ultimate pressing of the spike in accordance with Fig. 6 is then carried out by means of this single punch. After the ultimate pressing has been completed, the last step of the manufacture is reached, i.e. removal of the spike 5 out of the mould 10,20. This 5 is carried out so that the mould is opened by pulling the second mould 20 apart from the first mould 10. Hereupon the spike 5 is removed out of the first mould 10 by pushing by means of the punches 30,40. As regards the materials to be used in the manufacture of the spike 0 5, i.e. the first, second and the third material 1,2,3, the following can be stated briefly. As the first material 1, it is advantageously possible to use various ferritic, ceramic or equivalent sintering powders. Moreover, as material of the first material 1, it is also possible to use various mixtures or additives by means of which, for 5 example, the compatibility of the spike foot with rubber or the gliding properties of the spike in the tyre rubber are improved. Such mixtures are, e.g., various aluminium and graphite mixtures or 1 equivalent. The use of sintering powders is essential for the method in accordance with the invention, because, after the spike has been given its ultimate shape in the mould, it is sintered, i.e. subjected to a high temperature in an oven or equivalent so as to give the 5 product its ultimate hardness and strength. As the second material 2, of which the hard wear-resistant surface layer is formed for the spike, materials are used which have sufficiently high hardness. Such materials are, e.g., various sintering powders alloyed with tungsten, tantalum or titanium carbides or equivalent. In the spike manufac- •|Q tured in accordance with the method, as the third material it is advantageously possible to use the same material as the first material 1. As an alternative, as the third material, it is possible to use a material or a material alloy by means of which the toughness and/or the bending strength of the spike is improved. By means of the use ■J of such a material, e.g. , the risk of break of the spike can be reduced substantially. Above, the invention has been described by way of example with reference to the figures in the accompanying drawing. This is, however 20 not supposed to confine the invention to the exemplifying embodiment shown in the figures alone, but many variations are possible within the scope of the inventive idea defined the following patent claims. 25 30 35

Claims: 1 WHAT IS CLAIMED IS: 1. Method for the manufacture of a rivet for a fixed spike or for a sleeve-mounted spike, respectively, by pressing in a mould, c h a r - c a c t e r i z e d in that the method comprises the following step : the cavity space (11,12,21) in the mould (10,20), corresponding to the shape of the spike to be manufactured, is filled to the desired extent with a first material (1) to form the body part of the spike, 10 a first punch (30), whose diameter is substantially smaller than the diameter of the cavity space (11,12,21) in the mould, is fitted into the cavity space concentrically with the cavity space, and the annular space between said first punch (30) and the cavity space is filled •J with a second material (2) so as to form the wear-resistant surface layer for the spike, the first punch (30) is removed, and the space remaining after said punch is filled with a third material (3) , and 0 the spike is pressed to the desired shape and density, whereinafter the spike is removed from the mould. 2. Method as claimed in claim 1, c h a r a c t e r i z e d in 5 that, after the second material (2), which forms the surface layer, has been fitted into the mould (10,20), an intermediate pressing is carried out to compact at least said second material (2) . 3. Method as claimed in claim 2, c h a r a c t e r i z e d in that 0 the intermediate pressing is carried out by means of a hollow second punch (40) , which is fitted concentrically on the first punch (30) while the first punch (30) is fitted in the cavity space (11,12, 21) in the mould. 5 4. Method as claimed in claims 2 and 3, c h a r a c t e r i z e d in that the intermediate pressing is carried out by pressing by means of the first and the second punch (30,40) at the same time. ■ J 5. Method as claimed in any of the preceding claims, c h a r a c ¬ t e r i z e d in that the filling with the third material is carried out through the axial central hole in the second punch (40) . c 6. Method as claimed in any of the preceding claims, c h a r a c - t e r i z ,e d in that, after the filling with the third material (3) has been carried out, said third material (3) is pressed by means of the first punch (30) to the desired degree of compression. -|Q 7. Method as claimed in any of the preceding claims, c h a r c ¬ t e r i z e d in that the ultimate pressing of the product is carried out by at the same time pressing by means of the first and the second punch (30,40). • 8. Method as claimed in any of the claims 1 to 6, c h a r a c ¬ t e r i z e d in that for the ultimate pressing of the product the first and the second punch (30,40) are removed and the ultimate pressing is carried out by means of a single third punch. 20 9. Method as claimed in any of the preceding claims, c h a r a c - t e r i z e d in that the removal of the product out of the mould (10,20) is carried out after opening of the mould by means of a punch/punches (30,40) by pushing in the pressing direction of the punch/punches. 25 10. Method as claimed in any of the preceding claims, c h a r a c - t e r i z e d in that ferrous-metal based sintering powders, ceramic sintering powders or equivalent are used as the first material (1) . 30 11. Method as claimed in claim 10, c h a r a c t e r i z e d in that the material of the first material (1) is alloyed with aluminium, graphite or equivalent. 12. Method as claimed in any of the preceding claims, c h a r a c - 35 t e r i z e d in that a sintering powder alloyed with hardness- improving materials, such as with tungsten, tantalum or titanium carbides, is used as the second material (2). 1 13. Method as claimed in any of the preceding claims, c h a r a c - t e r i z e d in that the same material as the first material is used as the third material. 14. Equipment intended for carrying out the method as claimed in any of the preceding claims for the manufacture of a rivet for a fixed spike or for a sleeve-mounted spike, respectively, said equipment comprising a mould (10,20) provided with a cavity space (11,12,21), pressing equipment (30,40), and filling equipment, c h a r a c - 1Q t e r i z e d in that the mould is formed as a two-part mould so that the counter-faces (13,22) of the first mould (10) and of the second mould (20), to be placed one against the other, are placed in the widest portion of the cavity space of the mould in the area of the foot widenings (12,21) of the cavity space and that the press equip- ■J5 ment (30,40) comprises punches (30,40), which are fitted to act towards the second mould (20) substantially perpendicularly to the counter-faces (12,21). 15. Equipment as claimed in claim 14, c h a r a c t e r i z e d in 0 that the punches (30,40) are arranged to act jointly and in the same direction of pressing. 16. Equipment as claimed in claim 14 or 15, c h a r a c t e r ¬ i z e d in that the punches (30,40), which constitute the press 5 equipment, are arranged coaxially one inside the other. 0 5

Inventors: SUVANTO ERKKI, SUVANTO, ERKKI
Applicants: NESTE OY
Application year: 1989
Main classification: B22F3
IPC codes: B22F3, B22F5, B22F7, B29C43, B30B11