JPS6343448B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves moving the sliding surface of a cam relative to an energy generating device that generates energy such as arc heat along a meandering linear melting path, while heating the sliding surface of the cam with the energy generating device that generates energy such as arc heat. This invention relates to improvements in the method of melting and hardening white pig iron.

FIG. 1 shows an example of a device for hardening white pig iron while moving the sliding surface of a cam 2 of a camshaft 1 relative to an energy generating device along a meandering linear melting path 3. This device includes a drive mechanism consisting of a drive unit 4 and a follower unit 5 that meander the sliding surface of the cam 2 relative to the energy generator, and a TIG torch 6 as the energy generator.
It is made up of.

The drive unit 4 of the drive mechanism includes a main shaft 8 supported rotatably and movably in the axial direction by a base member 7, a main shaft rotation motor 12 connected to the main shaft 8 via a reduction gear 9 and gears 10 and 11; A rotating shaft 14 rotatably supported by the base member 7 and connected at one end to the motor 13; a central axis of the rotating shaft 14;
The central axis O ₂ is eccentric from O ₁ and fixed to the other end of the rotating shaft, and the eccentric shaft 16 is sandwiched between two bearings 15 attached to the approximate center of the main shaft 8, and the central axis O ₃ of the main shaft 8. The main shaft head 17 is attached to the main shaft with the center axis O ₄ eccentric from the camshaft 1, and the main shaft head 17 supports the camshaft with the center axis O ₅ of the camshaft 1 coincident with _{the center axis O 4 .} A positioning pin 18 that is supported in parallel so as to be freely retractable and inserted into the hole of the camshaft only when the camshaft 1 is at a predetermined initial position.
have. The cam 2, as shown in FIG.
A base circle portion 19 having a center of curvature about the central axis O ₅ of the camshaft 1, an eccentric circle portion 20 having a center of curvature O ₆ different from the base circle portion 19 and having a smaller diameter than the base circle portion, and the base circle portion It consists of connection parts 21 and 21' that smoothly connect the eccentric circle part 19 and the eccentric circle part 20,
In the connecting portions 21 and 21', the portions A-B and EF connected to the base circular portion 19 are formed in a curved shape, and the portions B-C and DE connected to the eccentric circular portion 20 are formed in a substantially straight line. It is formed. Camshaft 1 is cam 2
is supported by the spindle head 17 so that the center of curvature O ₆ of the eccentric circular portion 20 coincides with the central axis O ₃ of the spindle 8 . In addition, for various engines,
Since the distances between the centers of curvature O ₅ and O ₆ of the cam 2 are designed to be different, in order to correspond to this, the central axes O ₃ and O ₄ of the main shaft 8 and the main shaft head 17 are
A spindle head eccentric motor 22 and a spindle head eccentric drive device 23 move the spindle head 17 vertically in FIG. 1 relative to the spindle 8 so that the distance between the spindle 8 and the spindle head 17 can be changed. is provided in between.

The following unit 5 of the drive mechanism is connected to the camshaft 1
The camshaft 1 is supported by a head 24 whose central axis coincides with the central axis _O5 of the camshaft 1, and which is always biased to the left.

The TIG torch 6, which is an energy generator, has a tungsten electrode 25 connected to a power source and given a negative potential, and a gas nozzle 26 that covers the tungsten electrode 25. The gas nozzle 26 spouts argon gas for shielding. It's getting old. As shown in FIG. 2, the torch 6 is supported by a drive device 29 that meshes with a worm shaft 28 driven by a motor 27.
By driving 7, the cam 2 can reciprocate in the horizontal direction (back and forth direction in FIG. 1) along the sliding surface of the cam 2.

In the conventional white pig iron hardening method for the sliding surface of the cam 2 using the above-mentioned device, first, as a first step, the camshaft 1 is hardened between the spindle head 17 and the head 2.
4, and is moved to the initial position where the pin 18 enters the hole of the camshaft 1, and the portion B-C of the connecting portion 21 of the cam 2 is positioned horizontally as shown in FIG. . After that, the electrode 25 of the torch 6
is closely opposed to point A on the sliding surface of the cam 2.

Next, as a second step, argon gas is ejected from the gas nozzle 26, and a current is supplied between the electrode 25 and the cam 2, an arc is generated between them, and the sliding surface of the cam 2 becomes circular. is heated and dissolved. At the same time, by driving the motor 13, the eccentric shaft 16 is rotated, and the main shaft 8 and the cam 2 are rotated.
vibrates with respect to the electrode 25 with an amplitude narrower than the full width of the cam 2. At the same time, by driving the motor 27, the torch 6 having the electrode 25 is moved from point A to point C in the right direction in FIG. 2 via the drive device 29. Therefore, the electrode 25 meanderes along the melting path 3 while melting the sliding surface of the cam 2 in a circular shape, moves on the cam sliding surface from point A to point C, and spreads the sliding surface to a predetermined width. Heat and dissolve over a period of time.

When the electrode 25 reaches the position opposite the point C, only the movement of the torch 6 via the drive device 29 is stopped as a third step. At the same time, the main shaft rotation motor 12 is driven, and the main shaft 8 is rotated about the central axis _O3 . Since the central axis O ₃ coincides with the center of curvature O ₆ of the eccentric circular portion 20 of the cam 2,
The cam 2 rotates about this center of curvature _O6 as shown in FIG. Therefore, the electrode 25 of the torch 6
As in the second step, the cam 2 moves from point C to point D while meandering relatively over the sliding surface of the cam 2, and heats and melts the sliding surface over a predetermined width.

When the electrode 25 reaches the position facing point D, only the rotation of the cam 2 is stopped as a fourth step, and as shown in FIG.
-E is positioned horizontally. At the same time, the motor 27 is driven again, so that the torch 6 is moved rightward in FIG. 2 from point D to point F. Therefore, the second
Similar to the step, the electrode 25 moves from point D to point F while meandering on the sliding surface of the cam 2, heating and melting the sliding surface over a predetermined width.

In this conventional method, each motor 12, 1
3, 27 is constant, therefore the main shaft 8
The rotational angular velocity of the cam 2, the rotational angular velocity of the eccentric shaft 16, and the moving speed of the torch 6 are constant.

Here, when considering the position and relative movement speed of the cam width direction (horizontal direction in Figure 1) component of the relative meandering linear melting path 3 between the sliding surface of the cam 2 and the torch 6 at any point, R is Center axis of rotating shaft 14
Assuming that the amount of eccentricity between O ₁ and the central axis O ₂ of the eccentric shaft 16, ω is the rotational angular velocity of the eccentric shaft 16, and t is time, the displacement position x of the melting path 3 from the center of the cam width and the relative movement speed x〓 is expressed by the following equation.

x=Rcos ωt (1) x〓=−Rω sin ωt (2) As is clear from the above equations (1) and (2), in the conventional method, the rotational angular velocity ω of the eccentric shaft 16 is a certain value as described above. Since the value ω ₀ is a constant value, as shown in FIG. 4, the relative movement speed of the cam width direction component becomes a relative movement speed diagram of a sine curve in which the component in the cam width direction is highest at the center of the cam width. Therefore, in this conventional method, the residence time of the torch 6 on the sliding surface of the cam 2 is short at the center of the cam width, and is longest near both ends of the cam width, as shown in FIG. cam 2
The depth H of the white pig iron (chill) hardened layer 30 formed on the sliding surface becomes shallow at the center of the cam width. In addition, since the residence time of the torch 6 is long near both ends of the cam width, the amount of heating and melting of the cam sliding surface near both ends is large, the sliding surface melts too much, the molten metal flows out, and the shape of the cam 2 changes. As a result, the width B of the chill hardened layer 30 cannot be formed over the entire cam width.

An object of the present invention is to eliminate the drawbacks of the conventional method described above, and to increase the depth and width of the chill hardened layer at the center of the cam width, thereby improving the durability of the sliding surface of the cam. An object of the present invention is to provide a white pig iron hardening method for a cam sliding surface that improves wear performance.

In order to achieve the above object, the present invention moves the cam sliding surface in the cam width direction relative to the energy generating device by rotating the eccentric shaft of the drive mechanism, and also moves the cam sliding surface in the cam circumferential direction to generate energy. In the method of hardening white pig iron by heating and melting the cam sliding surface by moving it relative to the device and meandering the cam sliding surface with respect to the energy generating device, the rotational speed of the eccentric shaft is set to be the same as that of the energy generating device. The present invention proposes a method for hardening white pig iron on a cam sliding surface, which is characterized by slowing down the process when the device is located at the center of the cam width, rather than when the device is located near both ends of the cam width.

According to the above method of the present invention, the residence time of the energy generating device, that is, the torch is longer at the center of the cam width;
Since it becomes shorter near both ends of the cam width, the chilled hardened layer formed on the sliding surface of the cam reaches its maximum depth at the center of the cam width, and also minimizes the outflow of molten metal near both ends of the cam width. This makes it possible to form a chill hardened layer over the entire width of the cam, thereby improving the wear resistance of the sliding surface of the cam.

Embodiments of the present invention will be described below with reference to FIGS. 6 and 7.
This will be explained in detail with reference to the drawings.

The white pig iron hardening method for the sliding surface of the cam 2' according to the present invention uses the same equipment as that used in the conventional method described with reference to FIGS. Although this is implemented in steps, only the improvements made will be described in detail below.

In the method of the present invention, in the second to fourth steps, the relative moving speed of the cam width direction component of the sliding surface of the cam 2' at the center of the cam width is changed to the relative moving speed near both ends of the cam width. It is now controlled so that it is slower than the current speed. In detail, as an example of this control method, the motor 13 of the device shown in FIG. 1 is a servo motor or a pulse motor, and as shown in the rotational angular velocity control diagram of FIG.
The motor 1 is configured such that the rotational angular velocity ω of the eccentric shaft 16 becomes a minimum value ω ₀ −ω ₁ at the center of the cam width of the melting path 3 and a maximum value ω ₀ +ω ₁ near both ends of the cam width.
Control 3. By controlling in this way,
The relative movement speed of the cam width direction component of the cam sliding surface is controlled as shown in the relative movement speed diagram in Figure 6, and is slower in the center of the cam width and faster near both ends of the cam width. Become.

For example, as a specific example of the above control method, let ω ₀ be
80 rpm and ω ₁ to 10 rpm, and the maximum value of the rotational angular velocity of the eccentric shaft 16 is ω ₀ + ω ₁ =
90 rpm, and its minimum value can be ω ₀ −ω ₁ =70 rpm. However, this is just an example, and may vary depending on the material of the sliding surface of the cam 2', the output current of the torch 6, the preheating temperature, the width of the sliding surface, etc.

Therefore, according to the method of the present invention, the residence time of the torch 6 is longer at the center of the cam width and shorter near both ends of the cam width, so that the sliding movement of the cam 2' is reduced as shown in FIG. The chilled hardened layer 30' formed on the surface can have the maximum depth H' at the center of the cam width,
In addition, by minimizing the outflow of molten metal near both ends of the cam width, the width of the chilled hardened layer 30'
B' can be formed over the entire cam width.
As a result, the wear resistance of the sliding surface of the cam 2' can be improved.

In one example of the embodiment of the method of the invention described above,
Motor 1 for vibrating cam 2' in the axial direction
However, instead of vibrating the cam 2' in the axial direction, the present invention can also be applied to a device in which the torch 6 is vibrated in the axial direction relative to the cam 2' using an oscillator, for example. method can be adopted. In this case, the oscillator that vibrates the torch 6 may be controlled so as to obtain a relative movement speed diagram of the cam width direction component of the cam sliding surface as shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a partial schematic cross-sectional view showing an example of a device used in a white pig iron hardening method for a cam sliding surface, and FIGS. 2 and 3 are explanatory diagrams showing different steps of a white pig iron hardening method, respectively. Fig. 4 is a diagram showing the relative movement speed of the cam sliding surface with respect to the melting path position in the conventional method, Fig. 5 is a perspective view of the cam showing the chill hardened layer formed by the conventional method, and Fig. 6 is A diagram showing the eccentric shaft rotation angular velocity and relative movement speed with respect to the melting path position of the cam sliding surface in the method of the present invention,
FIG. 7 is a perspective view of a cam showing a chill hardened layer formed by the method of the present invention. 1...Camshaft, 2'...Cam, 4...Drive unit of the drive mechanism, 5...Following unit of the drive mechanism, 6...TIG torch (energy generator),
8...Main shaft, 13...Motor, 14...Rotating shaft,
16... Eccentric shaft, 25... Electrode.

Claims (1)

[Claims] 1 By rotating the eccentric shaft of the drive mechanism, the cam sliding surface is moved relative to the energy generating device in the cam width direction, and the cam sliding surface is moved relative to the energy generating device in the cam circumferential direction, and the cam In a method in which the sliding surface is meandered relative to an energy generating device and heated and melted by the energy generating device to harden white pig iron, the rotational speed of the eccentric shaft is set when the energy generating device is located near both ends of the cam width. A method for hardening white pig iron on a cam sliding surface, which is characterized by slowing down when the cam is located at the center of the width of the cam.