TW201540414A - Near-net-shape hot-rolling of guide rails - Google Patents

Abstract

The invention relates to a method for producing guide rails (11) for a linear rolling bearing, wherein a strand material (12) made of steel and having a constant initial cross-sectional shape (13) is provided, wherein said strand material has a length of at least 10 m, and wherein said strand material is hardenable at least in certain regions, wherein the strand material (12) is guided in succession through a heating apparatus (15) and a rolling apparatus (16) at a constant speed of transportation, wherein the strand material (12) is heated in the heating apparatus (15) to an austenitization temperature at which an austenite microstructure is present in the steel, wherein the strand material is plastically deformed in the rolling apparatus, and wherein the temperature of the strand material (12) is so high up to the end of the rolling apparatus (16); that an austenite microstructure is present. According to the invention, the strand material (12) is cooled, immediately after it has passed through the rolling apparatus (16), in such a way that a martensite microstructure forms in the hardenable regions thereof, wherein the strand material (12) is then ground (20) in order to obtain the finished guide rail (12), and wherein no further shape-changing machining takes place on the ground surfaces of the guide rail (12) between said plastic deformation (16) and said grinding (20).

Description

Hot rolling method for guiding machine near the final contour

The present invention relates to a method of manufacturing a guiding machine as described in the foregoing paragraph 1 of the patent application.

In the prior art, a method of manufacturing a guide for a linear rolling bearing is described in DE 10 2008 008 632 A1. Among them, the billet is first hot-rolled so that the billet is plastically deformed to obtain a cross-sectional shape close to the final cross-sectional shape of the guide. The blank is usually composed of curable steel, so that the contact surface of the manufactured guide has a sufficiently large hardness. After hot rolling, the blank is heat treated in such a way that it is not in a hardened state in order to carry out other manufacturing steps. These manufacturing steps include a cold drawing process in which the cross-sectional shape of the blank is altered by plastic deformation at room temperature such that it is close to the final cross-sectional shape of the guide, except for economical grinding. margin. The edge layer hardening of the cold drawn blank is usually carried out by heating the edge region of the blank to the Worthing temperature by means of an inductive heating device, wherein the edge regions are subsequently quenched, thereby producing a field Broken iron structure. The hardened blank is then ground to complete the manufacture of the guide.

An advantage of the manufacturing method proposed by the present invention is that the proposed method is relatively inexpensive.

According to the invention there is provided a method of manufacturing a guide for a linear rolling bearing, wherein a strip of material consisting of steel and having a constant initial cross-sectional shape is provided, wherein the strip of material has a length of at least 10 m, wherein the strip The material is at least partially hardenable, wherein the strip of material passes through the heating device and the rolling device one by one at a constant conveying speed, wherein the strip of material is heated to the Worthing temperature in the heating device, At this temperature, a Worthite iron structure is present in the steel, wherein the strip material is plastically deformed in the rolling device, wherein the temperature of the strip material reaches the presence of Voss before reaching the end of the rolling device The extent of the structure of the field iron, wherein after the strip of material passes through the rolling device, the strip of material is immediately cooled to the extent that a granulated iron structure is produced in the hardenable region thereof, wherein the strip material is subsequently subjected to the strip material Grinding to complete the machining of the guiding machine, wherein no other change in shape occurs on the ground surface of the guiding machine between the plastic deformation and the grinding Processing. The difference from the prior art is that the strip material is hardened after hot rolling, wherein the heat required for hot rolling is utilized. The cold drawing process step is completely omitted.

A hardenable steel such as C45E or 56 NiCrMoV 7 is preferably used as the steel material. However, carburized steel which can only be hardened in the surface area of carburization can also be used. Preferably, the steel grade is selected in such a manner that only the pure phase of the granulated iron structure exists after the heat treatment. The structure is preferably a fine needle type, and preferably has no coarse particles and a cracked mesh.

In the case of a strip of material having a length of at least 10 m, it is here in particular a strip of material which is produced discontinuously in the previous processing steps. The strip of material is also referred to as a continuous strip of material, it being apparent that the length of such strip of material is limited by the limited working time of the prior processing steps.

Depending on the type of steel used, it can be passed through unregulated cooling of ambient air, or through The cooling proposed by the present invention is carried out by means of an adjustable cooling, in particular by means of a cooling device. Here, by the preferred regulated cooling, the temperature characteristic curve during cooling can be adjusted in a manner to minimize the deformation of the strip material when the 麻田 loose iron structure is produced.

Advantageous developments of the invention are referred to the dependent items.

The strip material provided may have an initial cross-sectional shape that is circular and has a diameter of 20 mm to 90 mm. The hot rolled wire is preferably used as a strip material. More preferably, the surface of the wire is subjected to a cutting process, in particular by pre-turning and/or grinding. Thereby, the strip material provided can be removed after hot rolling, which may contain surface defects, or areas where the carbon content changes (especially decreases) in an undesired manner.

An uninterrupted strip of material can be provided by welding the ends of the continuous and limited blocks of strip material together. The limited blocks are preferably provided in a manner that is wound onto a reel or reel, wherein the blocks are removed from the reel and bent into a straight line prior to welding. The material stress generated in the above operation is then removed by heating to the Worthing temperature and the subsequent recrystallization process.

Corresponding solder joints can be cut from the strip material prior to grinding, without the use of such solder joints to make the guide. In the region of the welds, the reduced quality of the machined guide must be taken into account, so that the blocks are initially bent, wherein the steel material is preferably reused. Preferably, the spacing of the solder joints is selected such that the pitch is slightly greater than an integer multiple of the length of the plurality of strips of the strip of material that are ground in a process at the end of the method of the present invention. Broken block.

In the heating device, the strip material may be subjected to magnetic heating and/or induction heating and/or conduction heating. The induction heating is preferably carried out in a frequency adjusted manner. According to a comparison A preferred embodiment combines magnetic heating with subsequent low frequency induction heating. All of the proposed heating methods have in common that heating is very rapid. It should be pointed out here that, in principle, the time elapsed for the strip material to be transported from the beginning of the heating device to the end of the rolling device is very short. That is, the strip material has a higher Vostian temperature only for a very short period of time. Accordingly, the period of time during which the carbon in the layer close to the surface chemically reacts with the ambient air is also very short. Therefore, only a small degree of partial decarburization occurs. Undesired changes in the surface of the strip of material can be minimized by the use of a protective atmosphere in the area of the heating device and/or the rolling device.

The heating means heats the strip of material over its entire cross-section to a temperature which is at least equal to the Worthing temperature. Correspondingly, less material stress is generated in the strip material in the rolling device. There is no need to worry about the deformation of the strip material. It should be noted that in the conventional manufacturing method, only the surface of the strip material is heated to the Worthing temperature when induction heating is employed.

In the heating device, the strip material is preferably heated up to 2/3 of its melting temperature. In this way, an extremely precise cross-sectional shape of the strip material can be achieved in the rolling device. It should be noted that the economics of the present invention can be improved if only minimal material removal is performed during the final grinding of the strip material. Correspondingly, according to a preferred embodiment, a very precise cross-sectional shape of the guiding machine is achieved in the rolling device, which is very close to the desired final shape of the guiding machine.

The rolling device can have a plurality of rolling frames. It is preferred to evenly divide all the plastic deformations required into a plurality of rolling stands, so that only minimal and highly precise plastic deformations occur in each of the rolling frames. Plastic deformation occurring on the last rolling frame in the conveying direction The shape is preferably less than, and preferably much less than, the plastic deformation on the first rolling frame in the conveying direction. Each of the rolling frames preferably has a dedicated speed-regulated drive. The drive particularly preferably includes an electric motor, in particular a synchronous motor. When the speed adjustment of the drives is performed, the force acting on the strip material in the conveying direction is preferably taken into consideration, and is preferably used as a manipulated variable. Preferably, the strip of material is subjected to tensile stress. Preferably, the force is calculated taking into account the drive torque of the drives and/or the drive current of the electric motors.

The grinding allowance removed during the grinding of the strip material is preferably up to 0.5 mm.

The surface of the strip material provided may have a higher carbon content than the interior. This material state is preferably achieved by carburizing the strip of material. That is, the strip material is preferably enclosed in a carbon-containing environment (particularly carbon powder) and heat-treated.

It is to be understood that within the scope of the present invention, the features described above and below will be combined not only in the manners set forth herein, but also in other combinations or in separate applications.

10‧‧‧Transport direction

11‧‧‧Guide

12‧‧‧ strip material

13‧‧‧Initial cross-sectional shape

14‧‧‧ Cross-sectional shape after rolling

15‧‧‧ heating device

16‧‧‧Rolling device

17‧‧‧Cooling device

18‧‧‧Nozzles

19‧‧‧Separation device

20‧‧‧ grinding device

21‧‧‧ side of the guiding machine

22‧‧‧Top surface of the guiding machine

23‧‧‧ Underside of the guiding machine

24‧‧‧ Track

25‧‧‧symmetric plane

26‧‧‧Support area

27‧‧‧Rotary axis

30‧‧‧Ma Tian loose iron line

31‧‧‧First cooling curve

32‧‧‧second cooling curve

33‧‧‧ Third cooling curve

T‧‧‧cooling duration

T‧‧‧temperature

1 is a rough schematic view of a process of the present invention; FIG. 2 is a cross-sectional view of a rolled strip material; and FIG. 3 is a schematic diagram of continuous time-temperature conversion of a steel material 56 NiCRMoV 7.

The invention will be described in detail below with reference to the accompanying drawings.

Figure 1 is a rough schematic view of the process of the present invention. The first step of the method is to provide a strip of material 12 which preferably has an initial cross-sectional shape of a circle having a diameter of from 20 mm to 90 mm. The strip material is first passed through, for example, an inductive heating device 15. The respective electrical coils enclose the strip material 12 in a spiral shape. An alternating current is supplied to the electrical coil, which induces eddy currents in the strip material 12. The ohmic resistance of the strip material 12, together with the eddy current described above, results in rapid heating of the strip of material. The distribution and temperature distribution of the eddy currents can be controlled by the frequency of the fed alternating current and the shape of the induction coil. At higher frequencies, heating occurs primarily on the surface of the strip material 12. Preferably, the strip material 12 is heated over its entire cross-section to a Wolsing temperature, thereby producing a well-plastically deformable Worthite iron structure over the entire cross-sectional range.

Subsequently, the strip material 12 is passed through the rolling device 16. In contrast to the situation shown in the figures, a plurality of rolling frames arranged one after the other in the conveying direction 10 are actually provided, wherein the rolling frames respectively cause a small plastic deformation of one of the strips of material 12. The rollers of each rolling frame can process the strip material 12 from different sides. For example, the following scheme can be used: a rolling frame only processes the side faces 21, and a rolling frame immediately following it processes only the top and bottom faces 22; In particular, in the last rolling frame relative to the conveying direction 10, there may be a total of at least four rollers simultaneously acting on the strip material 12, wherein the at least four rollers are on the four sides 21 of the distribution; 22; 23 only caused a small plastic deformation. At the end of the rolling device, the strip material 12 has a cross-sectional shape 14 which, besides having a smaller grinding allowance, for example 0.3 mm, is the final cross-sectional shape after passing through the grinding device 20. The cross-sectional shape is consistent.

After passing through the rolling device 16, the strip material 12 is passed through the cooling device 17. The cooling device 17 can, for example, have a plurality of nozzles 18 distributed around the strip material 12. For example, water or oil can be sprayed through the nozzle 18 to the strip material 12 to cool the strip material. It is also possible to adopt a solution in which the temperature of the strip material 12 is much higher than the room temperature at the end of the cooling device 17, wherein, during the period of intermediate storage of the cut guide machine 11 before grinding, the final Cool to room temperature.

A separating device 19 is attached to the cooling device, for example, which is rapidly rotating, and the rotating shaft 27 is separated from the strip material 12 or the cutting wheel parallel to the conveying device 100. A plurality of finite blocks that are easily machined in the grinding machine are cut from the strip material 12 by a separating device 19. The length of these blocks is usually 6m.

After the cutting operation is completed, the strips of material are ground on a plurality of different grinding machines or grinding devices. In this case, the number of such grinding machines is selected in such a way that the method can operate continuously without having to collect the unprocessed strips of material after the separation device 19, and no individual grinding machines are present. The condition of use. In Fig. 1, the above-described grinding machine is simplified as two forming grinding wheels 20.

Figure 2 shows a cross section 14 of the rolled strip material 12. The cross-sectional shape 14 is mirror symmetrical with respect to the plane of symmetry 25 . The top surface 22 is slightly convex after rolling, wherein the top surface is ground to a flat shape during the grinding operation. On each of the two side faces 21 there are two rails 24 for the rolling bodies. The first point with respect to the finished guide is that the rails 24 are hardened so that the corresponding linear rolling bearing has a higher life. Shown here is a concave track 24 for a spherical rolling body. However, the method of the invention is also applicable to planar tracks for cylindrical rolling bodies. In principle, any number of tracks 24 can be made using the method of the invention. In particular, during the final grinding, the track 24 is machined with extremely high precision, so that the finished linear rolling bearing has a high guiding precision.

The bearing area 26 on the bottom surface 23 of the guiding machine is also described here. After the interior is completed, the guide is placed against the upper assembly by the support region 26. As shown, the bearing surface 26 is not completely planar after rolling. This unevenness is also eliminated during the final grinding process.

Figure 3 is a schematic illustration of the continuous time-temperature conversion of steel 56 NiCRMoV 7, which is, for example, perfectly suitable for use in practicing the method of the present invention. The horizontal line represents the logarithmic form of the cooling duration t in seconds, and the vertical line represents the temperature T of the strip of material in °C. This figure records two typical cooling curves 31; 32 obtained when the strip of material is cooled at different intensities. The cooling curves 31; 32 are all characterized by a cooling time t _8/5 which is the duration elapsed from 800 ° C to 500 ° C. Also shown is the Ma Tian loose iron wire 30, where it is located at 245 °C. This line 30 separates the area in which the Vostian iron structure is represented by A from the area in which the Matian iron structure is represented by M.

In the process control of the cooling process, it is preferable to ensure that the cooling is performed sufficiently quickly in the region under the granulated iron wire 30, thereby avoiding carbide precipitation as much as possible. This self-tempering effect causes a decrease in hardness and its interaction with micro-internal stresses in the structure contributes to micro-cracks.

In the case of the area on the Matian bulk line 30, the importance of cooling is relatively low because, as exemplified by 56 NiCRMoV 7, the carbon remains dissolved in the uncooled rammed iron.

After the Worthing at 860 ° C, 麻田散铁 (first cooling curve 31) having a hardness of 770 HV was obtained by t _8/5 = 7.5 seconds. After a brief hold time of 400 seconds in the area on the ERA wire 30 and further cooling according to the first cooling curve 31, the hardness as shown by the first cooling curve 31 is obtained. The above cooling process is illustrated by a third cooling curve 33. The different first and third cooling curves 31 are externally displayed; 33 is based on the logarithmic scale. A smaller hardness is produced when cooling is performed according to the second cooling curve 32 at t _8/5 = 153 seconds. If the cooling is accelerated according to the third cooling curve 33 from 280 ° C, the hardness is increased again.

In the case of the steel C45E which is also suitable for carrying out the method of the invention, the relationship shown in Fig. 3 will likewise occur in principle.

In order to simplify the temperature control according to the rolling heat, a steel having a lower carbon content can also be used as the starting material. After the corresponding adjustment of the hot rolled wire (surface defect, diameter, partial decarburization and/or decarburization), for example, the wire can be re-rolled. In the case of such a web comprising a surface-treated rolled wire, it can be simply heat treated, i.e., chemically modified to a layer close to the surface. The carbon content of the steel material is preferably increased by carburizing to such an extent that, in the case of corresponding cooling according to the rolling heat, there is a hardened member of the edge layer which can be used as a semi-finished material of the profile rail. In the adjustment of the carbon content and the carburization hardening depth, the above requirements for members subjected to rolling must be satisfied. The technical processing of such heat treated coils (including chemical modification of the surface) is also carried out in accordance with the above procedure.

In both cases, the machining allowance of the semi-finished material of the hot-rolled and hardened guide can be selected in a certain way, so that a simple mechanical process (milling, planing, scraping, grinding, etc.) can be used as required. In order to adjust the unheat treated area on the rail in a targeted manner.

10‧‧‧Transport direction

11‧‧‧Guide

12‧‧‧ strip material

13‧‧‧Initial cross-sectional shape

14‧‧‧ Cross-sectional shape after rolling

15‧‧‧ heating device

16‧‧‧Rolling device

17‧‧‧Cooling device

18‧‧‧Nozzles

19‧‧‧Separation device

20‧‧‧ grinding device

21‧‧‧ side of the guiding machine

22‧‧‧Top surface of the guiding machine

23‧‧‧ Underside of the guiding machine

27‧‧‧Rotary axis

Claims (10)

A method of manufacturing a guide (11) for a linear rolling bearing, wherein a strip material (12) composed of steel and having a constant initial cross-sectional shape (13) is provided, wherein the strip material has a length of at least 10 m Wherein the strip of material is at least partially hardenable, wherein the strip of material (12) passes through the heating device (15) and the rolling device (16) one by one at a constant conveying speed, wherein the heating device (15) heating the strip material (12) to a Worthing temperature at which a Worthite iron structure is present in the steel, wherein the strip material is plastically deformed in the rolling device, wherein Before reaching the end of the rolling device (16), the temperature of the strip of material (12) reaches the extent that the Wolster iron structure is present, wherein the strip material (12) passes through the rolling device (16) Immediately thereafter, the strip of material is cooled to the extent that a granulated iron structure is produced in its hardenable region, wherein the strip of material (12) is subsequently ground (20) to complete the guiding machine (11) Processing, wherein between the plastic deformation (16) and the grinding (20), in the guiding machine (11) On the other by changing the shape of the ground surface processing does not occur. The method of claim 1, wherein the strip material provided has an initial cross-sectional shape (13) that is circular and has a diameter of 20 mm to 90 mm. A method according to any one of the preceding claims, characterized in that an uninterrupted strip of material (12) is provided, in particular by welding the ends of several continuous and finite blocks of strip material together. The method of claim 3, characterized in that the corresponding solder joints are cut out from the strip material before the grinding (20), The welding points are not used to manufacture the guiding machine (11). A method according to claim 1 or 2, characterized in that the strip material (12) is subjected to magnetic heating and/or induction heating and/or conduction heating in the heating device (15). The method of claim 1 or 2, characterized in that the heating device (15) heats the strip material over its entire cross-section to a temperature which is at least equal to the Vostian temperature . The method of claim 1 or 2, characterized in that the strip material (12) is heated up to 2/3 of its melting temperature in the heating device (15). The method of claim 1 or 2, wherein the rolling device (16) has a plurality of rolling frames. A method according to claim 1 or 2, characterized in that the grinding allowance remaining at the time of final grinding (20) of the strip material is at most 0.5 mm. The method of claim 1 or 2, wherein the surface of the strip material (12) provided has a higher carbon content than the interior.