CN106029916A - System, production plant, and method - Google Patents

Abstract

The present invention relates to a system for local heating during the hardening of a workpiece, the system comprising an inductor for partially heating the workpiece and a side cooling device for limiting heat spread in the workpiece caused by the action of the inductor, the side cooling device being directly disposed on the inductor and capable of being fixed in place.

Description

System, manufacturing apparatus and method

technical field

The invention relates to a system for spatially limiting the heating of a workpiece during its hardening and a method for induction hardening, in particular selective case hardening, of a workpiece.

Background technique

Induction hardening is a common method for partially hardening workpieces and is known, for example, from document DE 10 2012 101304 A1. The alternating magnetic field caused by the inductor is conventionally guided here onto the electrically conductive workpiece. The magnetic field generates eddy currents in the target area (surface area of the workpiece), which cause the heating required for the hardening process. Typically temperatures of about 1000° C. can be achieved on the workpiece surface in this way.

This increased heat on the workpiece surface then itself acts as a heat source for regions of the workpiece which are arranged in the surrounding environment and which in some cases do not want hardening, or whose hardening is due to undesired thermal conduction effects. For example, it can arise that during the hardening of a rolling bearing two raceways are arranged so closely next to each other that heat propagation during the hardening of one raceway affects the other raceway. Therefore, it is possible that the required surface hardness is not achieved or cracks or raceway tempering occurs. The processes known from the prior art involving heat transmission by the inductors necessitate measures which again have to be adapted in a complex manner to each workpiece, in particular each raceway. Such a process is extremely disadvantageous if the interest is to carry out the production of rolling bearings, in particular large rolling bearings, fully automatically.

Contents of the invention

The object of the present invention is to provide a system by which a workpiece is heated with the help of an inductor to partially harden it and at the same time confines the resulting heat propagation to the area targeted for hardening. It is desirable here that the measures taken to this end allow an automatic and preferably simple hardening process to be included in the manufacture of rolling bearings, in particular large rolling bearings.

The invention achieves this object by a system for spatially limiting heating during hardening of a workpiece, wherein the system comprises an inductor for partially heating the workpiece, and for limiting the heat caused by the inductor in the workpiece. Side cooling system for heat spreading, where the side cooling system is arranged directly on the inductor.

Compared with the prior art, the present invention has the following advantage: The area of the workpiece directly adjacent to the target area can be cooled by means of a side cooling system, wherein the target area is to be understood as meaning the area intended to be heated by heating. hardened area. The heat spread of the workpiece can thus be limited to the target area.

Here, it is preferred that the workpiece is a rolling bearing, in particular a large rolling bearing. Such large rolling bearings are used, for example, in ferris wheels or wind power stations. The resulting forces require the application of high standards in terms of hardening so that rolling bearings can guarantee reliable operation over a long period of time. In particular, the system is therefore provided for hardening closed curves of workpieces, in particular the running surfaces of bearing rings. The inductor preferably comprises a coil or a conductor loop, in particular a copper coil, which can be subjected to an alternating current with a frequency between 2 kHz and 40 kHz. Thus, the target area on the workpiece is heated immediately (preferably within a few seconds) to a temperature of about 1000°C.

Advantageous refinements and developments of the invention can be obtained from the subclaims as well as from the description with reference to the drawings.

In another embodiment, the side cooling system is fixed in position relative to the inductor. This fixation additionally saves the user of the system from always having to reorient the cooling device to the desired position on the workpiece when the workpiece is changed.

In another embodiment, the system is arranged in a stationary manner and the workpiece is movable relative to the system in the processing direction, wherein the inductor and the side cooling system are arranged adjacent to each other in the processing direction. The inductor and side cooling system are preferably connected via supply lines to an electrical current or quenching medium for local cooling of the workpiece. By having a relative movement of the workpiece with respect to the stationary system, it can be particularly advantageous to avoid that the supply line would have to be dimensioned and configured such that the supply line would be followable during the otherwise necessary movement around the workpiece.

In another embodiment, the side cooling system comprises a basic body with an outlet hole for guiding a cooling jet comprising a quenching medium. In particular, the outlet hole predetermines where cooling is intended to take place close to the target area, wherein the outlet hole is advantageously dimensionally stable during hardening and thus the orientation of the cooling jet relative to the target area during hardening remain roughly constant.

In another embodiment, it is proposed that:

– the diameter of the exit hole and/or

– Orientation of exit hole

Adapted to the workpiece and/or to the heat spread caused by the inductor in the workpiece. For example, the exit holes are inclined with respect to a direction extending perpendicularly to the processing direction. In particular, the outlet opening is inclined such that the distance between the target area and the area cooled by the quenching medium is defined via the inclination. Furthermore, by dimensioning the diameter, the amount of quenching medium supplied to the workpiece can be determined or defined in a manner suitable for the workpiece. By controlling the cooling process, the heating required for hardening can advantageously be limited spatially to be individually adapted to the workpiece.

In another embodiment, the side cooling system comprises a pressure reducer and/or an adjustment screw for metering the volume flow of the cooling jet. With the help of a pressure reducer and/or an adjusting screw, the cooling by the side cooling system can be defined even more precisely. A precise adjustment via a pressure reducer and/or an adjusting screw is conceivable here. Furthermore, it is conceivable to change or readjust the cooling flow during the hardening process by means of a pressure reducer and an adjusting screw. The pressure reducer and adjusting screw are preferably part of a control loop which ensures that the set flow cooling is readjusted once it is determined that a temperature above a threshold is present in the system's surroundings.

In another embodiment, the adjustment screw can be fixed. Thus, it can advantageously be ensured that the cooling flow cannot be changed unintentionally during the hardening process.

In another embodiment, the system comprises a further side cooling system arranged directly on the inductor and capable of being fixed in place, wherein the inductor is arranged between the side cooling system and the other side along the process direction. between side cooling systems. Thus, heat propagation of the workpiece in a direction following the processing direction as well as in a direction opposite to the processing direction can be limited in an advantageous manner. This has the advantage, in particular for rolling bearings, that hardened regions which are re-entering the vicinity of the inductor but not yet heated due to the rotational movement of the rolling bearing during the hardening process are protected.

In another embodiment, the quench medium includes air, water, oil, solutions and/or emulsions. The quenching medium is preferably pre-cooled before it is supplied to the workpiece. Desired areas on the workpiece can be effectively cooled in a targeted manner with the aid of suitable quenching media.

In another embodiment, it is proposed that:

– the system includes multiple sensors,

– the sensor includes a sensor geometry adapted to the workpiece, and/or

- The base body includes a plurality of exit holes. As a result, several parts can be hardened simultaneously and the hardening process is thus advantageously accelerated.

In another embodiment, an auxiliary inductor is installed as a preheater upstream of the inductor, as viewed in the process direction.

In another embodiment, the system comprises a drive for the forward movement of the workpiece, wherein the forward movement can be controlled by the drive. The drive is preferably a roller drive causing an advancing motion of the workpiece. Furthermore, it is conceivable that a continuous movement of the workpiece can be achieved by the drive. The continuous movement of the workpiece provides optimal prerequisites for simple and positionally precise heating of the workpiece. It is also conceivable to accelerate and/or decelerate the forward movement by means of a drive during the hardening process.

Another subject-matter is a production plant for producing rolling bearings, preferably large rolling bearings, wherein the production plant comprises one of the systems described above. In particular, it is conceivable to obtain rolling bearings, preferably large rolling bearings, in a fully automatic manner by means of the manufacturing plant. It is advantageous here that the side cooling system for the raceway is fixed and therefore no longer needs to be locked in a complicated manner for each new workpiece or raceway.

A further subject is a method for induction hardening, in particular selective surface layer hardening, of a workpiece, preferably a large rolling bearing, wherein in a first method step the workpiece is heated by means of an inductor, wherein in a second method step by direct A lateral cooling system arranged on the inductor spatially limits the heating in the workpiece caused by the inductor. The first method step and the second method step are preferably carried out simultaneously. Thus, the heat propagation can advantageously be confined in the target area as soon as possible after generation.

In another embodiment, the workpiece is moved by means of a drive relative to a system comprising an inductor and a side cooling system, in particular relative to one of the systems described above.

In a further embodiment, the workpiece is formed, preferably cast and/or milled in zero method steps prior to the first method step. It is conceivable here to harden the workpiece immediately after it has been cast, forged and/or milled.

Further details, features and advantages of the invention emerge from the drawings and from the following description of preferred embodiments with reference to the drawings. The drawings illustrate only exemplary embodiments of the invention, which do not limit the important inventive concept.

Description of drawings

FIG. 1 shows a perspective view of a system for spatially limiting the heating of a workpiece during hardening according to a first exemplary embodiment of the invention.

FIG. 2 shows a system for spatially limiting heating of a workpiece during hardening according to a second exemplary embodiment of the invention.

Figures 3a to 3d each show a system for spatially limiting heating of a workpiece during hardening according to third, fourth, fifth and sixth exemplary embodiments of the present invention.

detailed description

In the individual figures, identical components are always provided with the same reference numerals and are therefore generally also named or mentioned only once in each case.

FIG. 1 shows a system 1 for spatially limiting the heating of a workpiece 10 during its hardening according to a first exemplary embodiment of the invention. For the hardening of the workpiece 10 , an inductor 2 is provided here, which is supplied with an alternating current and then acts partially, ie in a spatially limited manner, on the workpiece 10 by the magnetic field induced by the alternating current. During this process, in particular the surface layer of the workpiece 10 is heated and thus preferably heated to approximately 1000° C. within a few seconds. In the case of conventionally used materials, the heating produces as homogeneous austenite as possible in the surface layer and the highest possible fraction of martensite is formed by subsequent quenching of this heated surface region with a quenching medium . In particular, quenching is performed at high cooling rates using water jets that direct the quenching medium onto the workpiece. Depending on the geometry of the inductor, a heating depth or surface hardening depth distribution can be generated here, which can additionally be influenced by the temperature distribution in the surface layer of the workpiece or by the frequency of the alternating current, which frequency is preferably Ground is between 2kHz and 40kHz.

The workpiece 10 is preferably a rolling bearing, in particular a large rolling bearing as for example used in ferris wheels or wind power stations. Such a workpiece 10 is preferably formed, in particular cast and/or milled, in the initial stages of the hardening process. Here in particular the hardening takes place on the closed curves of the workpiece 10 , in particular the running surfaces of the bearing rings. For the hardening of the entire workpiece 10 or only in specific areas of the workpiece 10, the inductor 2 is arranged in a substantially stationary manner and the workpiece 10 is moved relative to the inductor 2 by means of a drive 8, in particular the workpiece 10 is segmented along the processing line. Direction B is guided past inductor 2 . The movement in the processing direction B preferably takes place continuously. Furthermore, it is conceivable that the inductor 2 is guided to the inside and/or outside of the workpiece 10 . In order to prevent heated surface regions from heating other regions of the workpiece 10 or other workpieces and thereby preventing their surface quality from being unintentionally affected, the system 1 comprises, in addition to the inductor 2 , a lateral cooling system 3 arranged directly on the inductor 2 . In particular, the side cooling system 3 is fixed, so that the user of the system 1 advantageously does not need to repeatedly reorient the side cooling system 3 in a time-consuming manner when the workpiece 10 is changed. The lateral cooling system 3 is preferably arranged behind the inductor 2—as seen in the process direction B—to protect the hardened region from re- and unintentionally heating. It is also conceivable that the side cooling system 3 is configured such that the side cooling system 3 prevents heat from propagating from the heated surface area, the target area, in multiple directions. For this purpose, for example, a cooling system on the other side is arranged upstream of the inductor 2 in the processing direction B in order to protect the not yet hardened regions of the workpiece 10 from unintentional heating. Especially in the case of rolling bearings, it is desirable if, after one revolution, the hardened area again reaches the vicinity of the inductor 2 or if the raceways are positioned so close to each other that heat propagation from one raceway heats the other raceway indirectly. Limit heat spread in the heated area (target area). This unintentional heating can result in not achieving the desired hardness or in cracking or tempering of the raceways.

FIG. 2 shows a system 1 for spatially limiting heating of a workpiece 10 during its hardening according to a second exemplary embodiment of the invention, wherein only the movement in the processing direction B is shown for the sake of clarity. Part of the workpiece 10. In particular, the system 1 according to the second embodiment of the invention comprises two inductors 2 on which respective lateral cooling systems 3 are arranged directly. The inductors 2 are arranged opposite one another with respect to the workpiece 10 , so that the workpiece 10 can preferably be hardened simultaneously along the inner side and along the outer side. The heat propagation of the workpiece 10 is positively limited or confined to the heating zone 9 by the side cooling system 3 .

Figures 3a to 3d show a system 1 for spatially limiting the heating of a workpiece 10 during its hardening according to a third, fourth, fifth and sixth exemplary embodiment of the invention, respectively. Herein, the system 1 is shown in each case in the detailed form known from FIG. 2 . It is provided here that the side cooling system 3 has an outlet opening 12 for conducting a cooling flow comprising a quenching medium. Quenching media preferably include air, oil, water or specific emulsions or solutions. The volume flow of the quenching medium can be defined here by the size of the diameter 7 of the outlet opening 12 . For example, the cooling flow directed towards the workpiece 10 will be greater in the case of the side cooling system 3 of Fig. 3a than that of the side cooling system of Fig. 3c, where the diameter 7 is smaller than in Fig. 3a. In addition, the cooling flow can be directed to a desired area relative to the area heated by the inductor 2 by orienting the outlet hole 12 . The general contour of the outlet aperture 12 is preferably inclined with respect to a direction extending perpendicularly to the process direction B, as shown in the embodiment of Fig. 3c. Additionally or alternatively, the metering of the volume flow can be regulated via the pressure reducer 17 .

List of reference signs

1 system

2 sensors

3 side cooling system

5 supply of quenching medium

6 Positioning device

7 Diameter of outlet hole

8 drives

9 heating zones

10 workpieces

12 exit hole

17 pressure reducer

Claims (15)

1. the system (1) for the most limited heating in hardening process of workpiece (10), wherein, described system (1) induction apparatus (2) for partly heating described workpiece (10) is included and for limiting by described induction apparatus (2) described The side cooling system (3) that the heat caused in workpiece (10) spreads, wherein, described side cooling system (3) is directly arranged at described sense Answer on device (2).

System the most according to claim 1 (1), wherein, described side cooling system is in position relative to described induction apparatus.

System the most according to claim 1 (1), wherein, described system (1) is arranged in the way of position is fixing, and institute Stating workpiece (10) can be mobile along processing direction (B) relative to described system (1), and wherein, described induction apparatus (2) and described side are cold But system (3) is disposed adjacently to one another along described process direction.

4., according to a described system (1) in aforementioned claim, wherein, described side cooling system (3) includes having The basic body of oral pore (12), described outlet opening (12) includes the cooling blast of hardening media for guiding.

System the most according to claim 3 (1), wherein,

The diameter of-described outlet opening (12) and/or

The orientation of-described outlet opening (12)

Be suitable to described workpiece (10) and/or the heat that is suitable to be caused in described workpiece (10) by described induction apparatus (2) spreads.

6. according to a described system (1) in aforementioned claim, wherein, described side cooling system (2) include by based on Measuring the decompressor (17) of the volume flow of described cooling blast and/or adjust screw, wherein, described adjustment screw can be consolidated Fixed.

7., according to a described system (1) in aforementioned claim, wherein, described system (1) includes being directly arranged at institute Stating the opposite side cooling system that induction apparatus (2) is gone up and can be in position, wherein, described induction apparatus (2) is along described process direction (B) it is arranged between described side cooling system (3) and described opposite side cooling system.

8. according to a described system (1) in aforementioned claim, wherein, described hardening media include sky gas and water, oil, Solution and/or emulsion.

9. system described in (1), wherein,

Described system (1) includes multiple induction apparatus (2),

Described induction apparatus (2) includes the induction apparatus geometry being suitable to described workpiece (10), and/or

Described basic body includes multiple outlet opening (12).

10. according to a described system (1) in aforementioned claim, wherein, described induction apparatus (2) along as described in process The upstream that direction (B) is observed is provided with the auxiliary induction device as preheater.

11. according to a described system (1) in aforementioned claim, and wherein, described system (1) includes for described workpiece (10) driver (8) of forward travel, wherein, described forward travel can be controlled by described driver (8).

12. 1 kinds of manufacture equipment being used for manufacturing rolling bearing, wherein, described manufacture equipment includes according to claim 1 to 11 In a described system.

13. 1 kinds of methods for inductively hardened workpiece (10), wherein, are added by induction apparatus (2) in first method step The described workpiece of heat (10), wherein, by being directly arranged at the side cooling system on described induction apparatus (2) in second method step (3) heating caused in described workpiece (10) by described induction apparatus (2) is spatially limited.

14. methods according to claim 13, wherein, described workpiece (10) can pass through driver (8) relative to including The system (1) of described induction apparatus (2) and described side cooling system (3), especially with respect in claim 1 to 12 System described in Xiang moves.

15. according to the method described in claim 13 or 14, wherein, in zero method step before described first method step Form described workpiece (10).