JP3074409B2 - Induction hardening method for sprocket wheel segments for construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless sprocket wheel for construction equipment, and more particularly to a method for induction hardening a sprocket wheel segment obtained by dividing the sprocket wheel into a plurality of segments.

[0002]

2. Description of the Related Art Sprocket wheels of endless tracks for construction machines require high hardness and wear resistance because the tooth surfaces and tooth roots (hereinafter referred to as teeth) that are in contact with the endless tracks are required. The outer peripheral surface is hardened by quenching. As a quenching method, as shown in FIG. 6, there is known a method in which a high-frequency induction coil 21 is arranged to face the outer peripheral surface of a sprocket wheel 20 and fixed blast quenching is performed by induction hardening. Normally, the sprocket wheel is formed as a single body as shown in FIG. 6, but in order to simplify the sprocket wheel replacement work recently performed at a construction site or the like, four to six sprocket wheels are used as shown in FIG. A segment-type sprocket wheel 23 assembled by dividing into two segments 2 has been put to practical use. When the sprocket wheel segments 2 constituting such a segment type sprocket wheel are individually subjected to high frequency induction hardening as in the case of the above-mentioned integral type, not only the outer peripheral surface having teeth but also hardening is not required. It hardens to the peripheral surface, and there arises a problem that it becomes difficult to machine the mounting portion of the inner peripheral surface after the quenching step. For this reason, in the conventional hardening of the sprocket wheel segment, only the teeth are hardened by one-tooth moving hardening.

[0003]

However, the one-tooth tooth quenching has a very poor productivity, uncured portions are generated for each tooth, abrasion resistance is poor, and overheated portions and the like are generated. There is a problem that a cured layer cannot be obtained and defective products are easily generated. An object of the present invention is to solve the above-described problems of the prior art in quenching a sprocket wheel segment of an endless track for a construction machine, and uniformize only a portion requiring quenching such as a tooth surface or a tooth bottom of a sprocket wheel segment. It is an object of the present invention to provide an induction hardening method for a sprocket wheel segment which can obtain a uniform hardened layer at a high depth without quenching and without overheating and is excellent in productivity.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method of induction hardening a sprocket wheel segment for a construction machine according to the present invention comprises feeding a sprocket wheel segment for a construction machine into an induction heating coil having a coolant injection hole. The cooling liquid is sprayed onto the inner peripheral surface that does not require quenching and hardening during heating by the coil to suppress the heating of the inner peripheral surface, and only the outer peripheral surface having the teeth is heated to the quenching temperature. Then, after heating, the outer peripheral surface is rapidly cooled and quenched. The coil for high-frequency induction heating is a sprocket
Outer surface facing the outer surface of the cut wheel segment
Coolant injection on the inner peripheral surface facing the inner peripheral surface
Having a hole, the coolant injection hole on the outer peripheral facing surface and the inner peripheral facing surface
Control the timing of coolant injection from the coolant injection holes
It can be controlled. The coil faces the sprocket wheel segment on the outer peripheral surface side at a small interval enough to heat the outer peripheral surface, and on the inner peripheral surface that does not require quench hardening, is about twice the interval on the outer peripheral surface. , The heat generated by the high frequency induction heating of the inner peripheral surface is effectively reduced.

[0005]

When the sprocket wheel segment is supplied into the coil, an induced current is induced in the sprocket wheel segment, which is a conductive material by the coil, and the sprocket wheel segment is heated. Since the cooling liquid is injected, the inner peripheral surface is always cooled while the coil is operating, and since the distance between the coil and the coil is large, the inner peripheral surface does not become high temperature and the cooling liquid is not supplied. Only the outer peripheral surface is heated to a predetermined quenching temperature. Therefore,
Even with one-shot quench hardening, quenching is performed only on the outer peripheral surface that needs to be hardened, preventing quenching of the inner peripheral surface that you do not want to harden, making it easy to machine in the later process. Products can be obtained.

In addition, since it is a one-shot quenching, the shape of the coil can be formed according to the shape of the tooth portion, and the outer peripheral surface requiring hardening can be hardened under uniform conditions. The tooth surfaces and roots of the segments are uniformly hardened without overheating, a hardened layer with a high depth is obtained, and a long-life product is obtained. In addition, because of the one-shot quenching, the working efficiency is extremely high and the productivity is improved as compared with the conventional single-tooth moving quenching. Therefore, even in the case of stationary one-shot quenching, quenching is performed only on the outer peripheral surface that requires curing, and quenching of the inner peripheral surface that does not want to be cured can be prevented, and machining in the subsequent process is easy. A good product could be obtained.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of an apparatus for performing an induction hardening method for a sprocket wheel segment according to the present invention. In the drawing, reference numeral 1 denotes an induction hardening device, which is a coil for induction heating having a structure for injecting a cooling liquid arranged so as to surround an outer peripheral portion of a sprocket wheel segment 2 in which a sprocket wheel is divided into four as shown in FIG. 3
And has a stationary type one-shot quenching structure. The coils 3 are arranged on the outer peripheral surface side of the tooth portion requiring quenching so as to face each other at a narrow interval enough to heat the outer peripheral surface according to the shape of the tooth portion. On the peripheral surface, they are arranged facing each other at relatively wide intervals. The distance between the inner peripheral surface of the sprocket wheel segment and the coil is preferably as large as possible to suppress heating, but if it is too far, power loss will occur. And an outer peripheral facing surface 5 facing the outer peripheral surface of the sprocket wheel segment 2,
2 and 3 are provided on the inner peripheral facing surface 6 facing the inner peripheral surface.
As shown in FIG. 5, cooling liquid injection holes 7 and 8 are formed respectively. The cooling liquid passages 10 leading to the liquid injection holes 8 are each provided with a cooling liquid supply port 1.
1 and 12 are separately connected to a coolant supply source via an electromagnetic valve (not shown) so that the coolant injection timing can be controlled separately. The coolant injection holes 7 for injecting coolant onto the outer peripheral surface of the sprocket wheel segment 2 are:
The sprocket wheel segments are provided at a high density so as to uniformly and uniformly spray a coolant over the entire outer peripheral surface of the sprocket wheel segment to enhance the quenching effect. In the drawing, reference numeral 13 denotes a coil power supply, and 14 denotes a lead wire.

[0008] With the above-described induction hardening apparatus, quenching of the sprocket wheel segments is performed as follows. When the sprocket wheel segment 2 is supplied into the coil 3 as shown in FIG. 1 by a work supply device (not shown), the coil 3 induces an induced current in the sprocket wheel segment, which is a conductive material, and the sprocket wheel segment Is heated, and at the same time, the coolant is supplied into the coolant supply passage 10, and the coolant is ejected from the coolant ejection holes 8, so that the coolant is ejected on the inner peripheral surface of the sprocket wheel segment.
Therefore, the inner peripheral surface of the sprocket wheel segment is constantly cooled during operation of the coil, and since the distance between the coil and the coil is large, the inner peripheral surface does not reach a high temperature and the outer peripheral surface to which the coolant is not supplied. Only the quenching temperature is heated. When the outer peripheral surface is heated to a predetermined temperature, the cooling liquid is supplied into the cooling liquid passage 9 and the cooling liquid is simultaneously injected from the cooling liquid injection holes 7 to the outer peripheral surface, so that the teeth are rapidly cooled. As shown in FIG. 4, a uniform hardened layer 15 having a high depth was formed only on the outer peripheral surface.

The endurance sprocket segment for construction machinery thus hardened was subjected to a hardness test by selecting five points on the tooth surface and the tooth bottom. As a result, the surface hardness was in the range of HRC 56 to 58 at all measurement points. And a uniform cured layer was obtained. The same measurement was performed on the inner peripheral surface other than the tooth portion, but the hardness of the inner peripheral surface was in the range of HRC 18 to 20, and no hardened layer was observed.

[0010]

As apparent from the above description, the present invention has the following special effects. It is possible to quench only the outer peripheral surface of the sprocket wheel segment that needs to be hardened by stationary one-shot quenching, and it is possible to obtain a good product that is easy to machine in the post-process. The work efficiency of hardening the sprocket wheel segment for the endless track of the construction machine, which had been carried out, was greatly improved. In addition, since it is one-shot quenching, quenching of the outer peripheral surface that requires hardening is performed uniformly,
The sprocket wheel segment tooth surface and root are hardened uniformly without overheating, and a deep hardened layer can be obtained.The life of the sprocket wheel segment can be dramatically improved compared to the conventional sprocket wheel segment. Was.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an induction hardening apparatus embodying the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along the line BB of FIG. 1;

FIG. 4 is a schematic diagram showing a quenched state of a sprocket segment.

FIG. 5 is a front view of a segment type sprocket wheel for an endless track of a construction machine.

FIG. 6 is a schematic view of a conventional induction hardening device for a sprocket wheel for an endless track of a construction machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Induction hardening device of sprocket wheel segment 2 Sprocket wheel segment 3 Coil 7, 8 Coolant injection hole 9, 10 Coolant path

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C21D 1/10 C21D 1/42 C21D 9/32

Claims (1)

(57) [Claims] 1. A sprocket wheel segment for a construction machine.
For construction machinery that performs one-shot quenching of parts by high-frequency induction heating
Induction hardening of sprocket wheel segments
Therefore, the coil for high frequency induction heating is
With the outer peripheral surface and the inner peripheral surface facing the outer peripheral surface of the
Each having a cooling liquid injection hole on the facing inner peripheral surface,
Coolant injection holes on the outer facing surface and cooling liquid injection holes on the inner facing surface
To control the timing of coolant injection from
And has a sprocket wheel segment
On the outer peripheral surface side, a narrow enough space to heat the outer peripheral surface
And the outer surface on the inner surface that does not require quench hardening
Are arranged to face each other at a wider interval than
The quenching construction machine sprocket wheel segment is fed into the coil and positioned therein, and the inner peripheral surface is opposed to the inner peripheral surface which does not require quench hardening during heating by the coil.
The cooling liquid is injected from the cooling liquid injection holes on the surface to suppress the heating of the inner peripheral surface, and only the outer peripheral surface having the teeth is heated to the quenching temperature, and after the heating , the cooling liquid is injected from the cooling liquid injection holes on the outer peripheral facing surface. An induction quenching method for sprocket wheel segments for construction machinery, wherein quenching is performed by spraying to rapidly cool the outer peripheral surface.