JPH0235803Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a device for hardening the surface of a cast iron workpiece, especially the running surface of a cam or swinging arm, by melting the surface with an arc and then cooling it. a workpiece support to be adjusted and a crank drive for adjusting the oscillatory movement of the workpiece support, said workpiece support being adjustable by a motor via the crank drive; Regarding formal matters.

Devices with linearly adjustable workpiece supports and drives for vibrational adjustment of the workpiece support are known, in which case the workpiece support is adjusted by a motor via a crank drive. (Federal Republic of Germany Patent No. 2703469)
Specification of the Federal Republic of Germany Utility Model Registration No. 2839930 and Specification of the Federal Republic of Germany Utility Model Registration No. 7702409).

With this type of device, the surface of the workpiece is hardened and hardened in a trajectory extending along the surface in an undulating manner. While the workpiece is rotated about its axis, the arc core, which hardens the surface of the workpiece, is moved from a central position to both sides with a substantially coordinated period of oscillation. In this case, the speed of the oscillation is maximum in the central position, ie in the middle of the workpiece to be hardened, and decreases towards the edges.
The superposition of the rotational movement of the workpiece and the orbital movement of the arc core gives an approximately sinusoidal velocity distribution, with relatively low velocities occurring at the edges of the melting trajectory.
However, the result is that the depth of hardening at the edges of the workpiece becomes deeper than at the center of the workpiece.
Therefore, if a satisfactory hardening depth is achieved in the central region, there is a risk of molten material flowing out of the workpiece at the edges of the workpiece. The more or less large loss of shape of the workpiece produced in this way is a disadvantage. Shape loss is particularly disadvantageous if the workpiece is polished after hardening, as is usually the case. Different depths of melting or hardening caused by different orbital velocities of the arc core clearly occur if the hardened layer flows out too much. It is quite clear that the hardening depth varies along the melt trajectory.

It is therefore an object of the invention to provide a device for hardening the workpiece to be hardened with a hardening depth that extends approximately uniformly along the entire surface, in particular at right angles to the center line of the workpiece. It is to be.

In order to solve this problem, the device according to the invention is provided with a linearly adjustable workpiece support and a drive for vibratory adjustment of the workpiece support. and in which the workpiece support is adjustable by a motor via a crank drive, the crank drive being cyclically varied in rotation speed such that:
This means that the workpiece is driven in relative motion with respect to the arc center at an approximately constant speed but at high speeds at the turning points of the movement and/or at the point of return.

According to an embodiment of the invention, the crank drive is driven via two oval gears. In a further embodiment, the crank drive is driven by a speed-controlled motor.

For a uniform hardening depth, only the relative movement of the workpiece to the arc is involved, and the trajectory speed can be arbitrarily high in a given trajectory segment that is not melted, thus avoiding the need for unnecessarily large drive units. For the purpose of displacement, in each case the part with the smallest mass participating in the relative movement is driven.

With the device of the invention, the arc and the workpiece are connected in such a way that the workpiece surface is melted with a substantially uniform melting depth, taking into account the spacing of adjacent striations and taking into account the mass distribution of the workpiece. The relative speeds of can be made to vary within the range of the striations.

Additionally, heat transfer at orbital speed and trajectory course are taken into account.

In other words, in the case of a cam, for example, the top of the cam, which has a large spacing from the camshaft axis and whose heat transfer is therefore relatively low due to this spacing, is located relatively close to the camshaft axis. and therefore pass at a higher orbital velocity than the surface areas where the heat transfer is relatively greater as the heat flows to the adjacent camshaft. When the striations are closely spaced together, as is the case, for example, at turn points, they pass through the surface at high trajectory velocities. Changing orbital velocities in such materials is easily investigated experimentally.

Furthermore, the device of the invention is used in various forms in practice. In short, it is possible to produce a zigzag-like course in the workpiece, and also a zigzag-like course of the melting path by means of a worm gear or a controlled motor. The zigzag course of the melting trajectory is
A track segment from one edge to the other edge is passed at a constant track velocity low enough for melting, whereas another track segment from said other edge to said one edge is passed at a relatively high It is also changed by being passed at orbital speed, so that no melting of the surface is achieved in such a return course. Furthermore, one shape of the zig-zag melting trajectory is such that the spacing of adjacent track segments varies across the width of the surface to be melted; There are some things for which is constant. In the case of a serpentine melting trajectory, the relative speed between the workpiece and the arc at the turn-around point must be sufficiently high so that excessive melting does not take place at the edges. On the contrary,
The lateral movements required for the melting trajectory are performed at sufficiently low relative velocities for melting. Advantageously, the workpiece is rotated gradually relative to the transverse movement with respect to the arc.

The different speeds required at different points on the surface to be melted can be achieved in different ways.

The invention will be explained below with reference to the illustrated embodiments.

In FIG. 1, a camshaft is designated by the reference numeral 1, about which a cam 2 is rotatable and subjected to an oscillatory movement in the direction of the double arrow. The arc core of the arc burner melts the cam surface along one trajectory and the material is allowed to slowly cool. The edges of the cam running surface are not melted.

To vibrationally support one side of the camshaft according to FIG. 1, the device according to FIG. 2, which shows part of the hardening machine for the cam according to FIG. 1, serves. a support beam 20 movable in the direction of the pins 21 and translationally with these pins;
receives one side of the camshaft of FIG. 1 in the receiving member 22. The other side of the camshaft is supported in a corresponding bearing and is supported by a spring force on the receiving member 22.
It is crimped against.

A support beam 20 is hinged to link triangular members 25, 26 via connecting rods 23, 24. Link triangular members 25 and 26 are connected to each other via a rod 27. A connecting rod 27a is connected to the link triangular member 26, so that the connecting rod 27a is connected to the link triangular member 26.
a, a reciprocating movement is produced in the rod 27 and a corresponding oscillating movement of the support beam 20 is caused in the connecting rod 2.
It is produced in the direction of 3 and 24. Connecting rod 27a
is connected to a crank wheel 28 via an adjustment member, and the connecting rod 27a and crank wheel 28 form a crank drive device. By adjusting the articulation point of the articulation rod 27a on the crank wheel 28, the vibration stroke of the support beam 20 is adjusted.

Two oval gears 29, 30 are used to drive the crank wheel 28, which oval gears provide the crank wheel with a periodically varied drive speed;
This drive rotational speed results in a substantially uniform relative movement of the electrode with respect to the cam surface over the cam width and a relatively high velocity at the turning point. The oval gearwheel 30 is driven by a corresponding mechanically regulated transmission via a three-phase alternating current motor 31.

The two oval gears 29, 30, which are always in mesh with each other in such a way that the radius of the teeth in mesh with each other is always constant in total, cause the number of revolutions periodically varied by the crank to be changed as follows: , such that the speed of the vibrating support beam 20 is approximately constant in the direction of the camshaft 1 and relatively large at the point of return of the movement, ie at the end of the cam. Therefore, the dwell time occupied by the arc center at the turning point of the cam trajectory is relatively short.

In the device shown in FIG.
drives two oval wheel transmission members 32, 33 via a transmission 31A, the drive wheels 33 of which are optionally adjustable via reduction gears 34, 35. The crank triangular member 38 drives the crank drive devices 36 and 37 which are
The supporting beam 20 is driven in accordance with FIG.

Furthermore, the above-mentioned device can be replaced by a motor drive comprising a speed-controlled DC motor or the like.

The present invention is not only used for camshafts. For example, swing arms that are not rotationally symmetrical can also be hardened with the device according to the invention. In the rocker arm cooperating with the camshaft, the substantially rectangular surface in contact with the camshaft is hardened.

Furthermore, other motor vehicle parts with rotationally symmetrical or non-rotationally symmetrical construction can also be hardened advantageously with the device according to the invention.

The device described above works by slow cooling of a molten metal strip. However, the device according to the invention can also be adapted in such a way that the melt streaks undergo rapid cooling, for example by means of an auxiliary medium such as air or water.

[Brief explanation of the drawing]

Figure 1 is a side view of the cam with its surroundings melted;
The figure is a perspective view showing the constituent members of a device for hardening a cam, and FIGS. 3 and 4 are perspective views showing different embodiments of the drive device of the device according to the present invention. DESCRIPTION OF SYMBOLS 1...Camshaft, 2...Cam, 20...Support beam, 21...Pin, 22...Receiving member, 23,2
4... Connecting rod, 25, 26... Link triangular member,
27... Rod, 27a... Connecting rod, 28... Crank wheel, 29, 30... Oval gear, 31... Three-phase AC motor, 31A... Transmission device, 32, 33...
...Oval car transmission member, 34, 35... Reduction transmission device, 36, 37... Crank drive device, 38...
Link triangular member.

Claims (1)

[Claims for Utility Model Registration] 1. A device for hardening the surface of a cast iron workpiece by melting and then cooling the surface of the arc workpiece, comprising a linearly adjusted workpiece support and the workpiece. a crank drive for regulating the oscillatory movement of the support, in which the workpiece support is adjustable by means of a motor via the crank drive, a crank drive 27a; 28; 36, 37 are rotational speeds that are changed periodically, such that the workpiece 2 moves relative to the arc center at an approximately constant speed but at high speeds at turning points and/or return points of the movement; A device for hardening the surface of a cast iron workpiece, characterized in that the device is adapted to be driven. 2 crank drive device 27a, 28; 36, 37
is driven through two oval gears 29, 30; 32, 33 Utility model registration claim 1
Apparatus described in section. 3. The device according to claim 1, wherein the crank drive device is driven by a motor whose rotation speed is controlled.