In continuously operated extrusion, the material to be extruded is conducted to a groove made on the outer circumference of a wheel-like element i. e. feed element.

As the feed element rotates around its axis, the material to be extruded gets into contact with a counterpart, i. e. an abutment element essentially filling the groove, so that the motion of the material to be extruded with respect to the wheel-like element is changed. Thus the material is fed into extrusion in the proceeding direction thereof, through an extrusion aperture provided in the extrusion element prior to the abutment element. The method utilizes the thermal energy created in the friction and in the deformation process. By means of the method, it is possible to extrude essentially long objects with advantageously different transversal surfaces.

The pressures and temperatures used in the extrusion of metallic material are high.

Typically in continuously operated copper extrusion, where high production speeds are pursued, the temperature rises up to the range of 600-700 °C. Said conditions result in the wearing or breaking of extrusion tools, and thus to a shortening of their working age. With respect to wearing, the most critical element of the extrusion tools is the abutment element, because it is subjected to the highest pressure and temperature in the whole extrusion process, which sets high requirements to the toughness and hardness of the abutment element material.

The material usually employed in tools and abutment elements in particular is tool steel or a corresponding tough, wear-resistant material. Tool steels do not endure the required higher temperatures and pressures. It is well-know to improve the wear-resistance of the extrusion tools by cooling. It is also known to prevent the

temperature from rising in the abutment element for example by feeding cooling agent inside the abutment element.

The rising of the temperature in tools can be prevented for example in a way described in the US patent 4,610, 725, by conducting the cooling agent into the groove, both through the material feed aperture and directly through an auxiliary feed aperture provided for the cooling agent. The method according to the publication for cooling the abutment element may result in an uneven cooling of the abutment element, and further in problems in the practical realization of the whole equipment.

When the wear-resistance of the abutment element is attempted to be improved by an internal cooling agent circulation, the procedure results in particularly high heat gradients in the abutment element, and consequently in the breaking of fragile abutment element materials, especially when there are intensive fluctuations in the temperature. The temperature fluctuates for example when starting and ending a production batch. That surface of the abutment element that gets into contact with the material to be extruded is heated remarkably more than the cooled center part of the abutment element. Heat tensions caused by high heat gradients can break the structure of the abutment element, and thus its working age may remain short.

The object of the present invention is to introduce a novel solution for performing continuous extrusion, so that drawbacks of the prior art are eliminated. The continuous extrusion process is improved by affecting the structure and material of the abutment element.

The invention is characterized by what is set forth in the characterizing parts of the independent claims. Other embodiments of the invention are characterized by what is set forth in the rest of the claims.

Remarkable advantages are achieved by the arrangement according to the invention. By means of the invention, by affecting the structure and material of the counterpart, i. e. the abutment element, the working life of the abutment element can be extended, and production speeds can be remarkably improved. By employing hard powder metallurgical material as the material of the abutment element, as well as a separate supporting structure that cools the abutment element, there is achieved a structure that is both strong and wear-resistant for demanding extrusion conditions. The abutment element according to the invention has an excellent temperature and pressure resistance. The cooling support structure includes a support surface, and the heated abutment element is installed in parallel with the plane defined by said support surface, so that the thermal expansion of the abutment element can be controlled. According to the invention, deformations caused by the thermal expansion of the abutment element are possible without breaking the internal structure of the abutment element or other surrounding tool structures. The abutment element is heated through its extrusion surface that is in contact with the material to be extruded. Respectively, the abutment element is cooled through its slide surface that is in contact with the support surface of the cooling support structure. Advantageously the support surface extends along the whole width of the slide surface. When the cooling of the abutment element is realized through an even support surface, there is achieved an effective cooling, while heat tensions in the abutment element are at the same time minimized. The cooling support structure is provided with cooling agent circulation, and the positioning and measures of said cooling agent circulation can be used for distributing the cooling power on the support surface, and consequently heat tensions in the abutment element can be minimized.

When the abutment element is essentially thin, with a maximum thickness of 10 millimeters, also the deformation effects caused by the temperature rise remain slight. The extrusion surface and slide surface of a abutment element according to the invention are parallel. The abutment element can be easily manufactured for

instance in limited series production, and owing to its shape, it can be easily installed in place in the extrusion equipment. Remarkable savings are achieved by the solution according to the invention, as regards the material expenses of continuous extrusion equipment, and the working life of the different parts of the equipment is extended.

The invention is described in more detail below with reference to the appended drawings.

Figure 1 Equipment according to the invention Figure 2 Cross-sectional view of figure 1 Figure 3 Cross-sectional view of figure 1 In the equipment 1 according to figure 1 for performing continuous extrusion the material to be extruded 2, such as copper, is brought to the feed element 3 grooved on its outer circumference and further to the groove 4 provided on the outer circumference of the feed element. The abutment element 6 arranged partly in the groove 4 forces the material to be extruded 2 to change direction towards the feed plate 7 and further to the extrusion element 5, from where the material to be extruded is pressed out as an extrusion product, in the form defined by the extrusion nozzle belonging to the extrusion element. Typically the groove 4 is provided with a lining made of the same material as the material to be extruded 2.

The equipment 1 also includes a housing element 9 for supporting the above described elements of the equipment. The housing element 9 comprises a required number of parts made of wear-resistant material, which parts can be mutually attached.

The temperature in the abutment element 6 rises intensively during the extrusion of the material 2. According to the invention, in connection with the abutment element 6, there is provided a separate cooling support structure 12 for supporting and

cooling the abutment element. The cooling support structure 12 can constitute part of the housing element 9, or it can be a separate structure, and it is made for instance of tool steel. Inside the support structure 12, there is arranged cooling agent circulation 13 for achieving the cooling feature of the support structure. The cooling agent circulation is placed in the support structure so that heat tensions in the abutment element are minimized. The support structure 12 includes a support surface 14, and in the direction of the plane defined by said support surface, the heated abutment element 6 is installed so that the thermal expansion of the abutment element can be controlled. The abutment element 6 is provided with an extrusion surface 10 that is in contact with the material to be extruded, through which extrusion surface the abutment element is heated. The abutment element includes a slide surface 11 that is in contact with the support surface 14 of the support structure. The support surface 14 of the cooling support structure 12 essentially extends over the whole width of the slide surface 11 of the abutment element 6. The cooling of the abutment element heated in the extrusion process is realized through the support surface 14 of the cooling support structure 12. As the abutment element tends to expand while it is heated, this is possible in the direction of the plane parallel to the support surface 14 of the support structure 12.

In that case, the deformations occurring in the abutment element owing to the heat can be controlled, so that they do not break internal or external structures of the abutment element. The extrusion surface 10 and the slide surface 11 are mutually parallel. The distance C between the extrusion surface 10 and the slide surface 11 is 10 millimeters at most, preferably 5-10 millimeters. The thermal expansion of the abutment element in the direction of the support surface 14 is typically about 0.01-0. 02 millimeters. According to an example, the abutment element is manufactured of stellite or other corresponding hard, powder metallurgical material.

Figure 2 is a cross-sectional view of figure 1 at the section A-A. In figure 2, there can be distinguished a projection 15 belonging to the abutment element 6, said projection extending as far as the bottom of the groove 4 provided in the feed

element 3 at that point of the feed element where the material to be extruded is forced into the extrusion element 5. Of the abutment element 6, outside the groove 4 remains the top part 19 of the abutment element, and the lugs 17 and 18 belonging to said top part are in contact with the feed plate 7 that in part holds the abutment element 6 in place. The top part 16 of the abutment element 6 touches the extrusion element 5 that also in part holds the abutment element 6 in place.

The abutment element can be thermally expanded within the tolerances defined by the extrusion element 5, the feed plate 7 and the housing structure 9. Figure 3 is a cross-sectional view of figure 1 at the section B-B. The molten material to be extruded 2 fills the groove 4 and penetrates through the slot 8 provided in the feed plate 7 onto the extrusion element 5 to be extruded.

For a man skilled in the art, it is obvious that the various embodiments of the invention are not restricted to the above described examples, but may vary within the scope of the appended claims.