JPS60208421A - Method for induction-hardening gear - Google Patents

Abstract

PURPOSE:To increase the toughness of the roots of the teeth of a gear and to improve the fatigue strength by forming triangular projections on the inside of a circular high-frequency induction heating coil so that the shape of the inside of the coil corresponds to the shape of the outside of the gear and by hardening the gear along the outline. CONSTITUTION:Triangular projections 12 formed on the inside of a circular high-frequency induction heating coil 11 are put in the spaces among the bottoms 2 and the sides 3 of the teeth of a gear and the inside of the coil 11. The gear is induction-heated so as to make the temp. of the bottoms 2 higher than the temp. of the tips 1. A coolant is then spouted from coolant nozzles 14 fixed on the inside of the coil 11 toward the gear along the surfaces of the projections 12 to harden the gear along the outline.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for induction hardening gears, and more particularly to a method for induction hardening a small gear in its entirety and profile hardening.

Gears are generally induction hardened to improve wear resistance and fatigue resistance.

In general, induction hardening involves passing a high-frequency current through a coil to induce eddy currents on the surface of an object to be heated, such as a gear.The surface of the object to be heated is heated by the Joule heat of the eddy current, and then cooled. It is hardened. When heating °ζ gears for such induction hardening, for small gears,
After the gear is induction-heated while rotating around its axis in an annular high-frequency induction heating coil whose inner surface is a circumferential surface, coolant is injected from coolant injection holes provided on the inner circumferential surface of the coil to heat the gear. It is rapidly cooled and hardened. For gears with large face widths, the gear is induction heated while moving the coil in the direction of the copper shaft, and then immediately rapidly cooled and hardened.

However, according to the conventional induction hardening method for the entire small float, the gap between the inner circumferential surface of the coil and the tips and bottoms of the teeth is large, so the tooth width is usually heated from the top to the bottom. As a result of the heat soaking, the entire ridge portion of the gear including the tooth tip 1 and C1 bottom 2 is hardened, as shown by the shaded area in Fig. 1. In addition to not being able to form a deep hardened layer, the floats have a multi-layered surface shape. It is not cooled properly, causing uneven hardness and quenching cracks, and large quenching distortions.

6 Already related to the above, Proceedings of the Japan Society of Mechanical Engineers, Part 1, No. 27
Volume 182 (Showa 36) contains approximately 500 small gears.
After preheating in a furnace or high frequency to ℃, high frequency heating with a ring coil, rapid cooling, and quenching. A method of +S hardening has also been reported; even with this method, the hardness of the tip of the tooth is lower than that of the bottom (<, the hardness is not contour hardened to a uniform hardness.

Another method has also been proposed in which, after high-frequency heating of the float, the float is placed in a cooling chamber with a corrugated inner circumferential surface, and a coolant is injected from the corrugated surface in the normal direction to harden the float. , the tooth bottom is not hardened sufficiently.

The present invention has been made in order to solve the above-mentioned problems, and is a method for induction hardening the entire gear, which can form a hardened layer having uniform hardness and depth on the surface layer of the tooth portion and tooth bottom. Our aim is to provide the following.

In the present invention, after a gear is placed in an annular high-frequency induction heating coil and the gear is heated by induction, a coolant is injected onto the gear from a coolant injection hole provided on the inner circumferential surface of the coil to rapidly cool the gear. In the induction hardening method for gears, triangular protrusions formed on the inner circumferential surface of the coil are inserted between the tooth surfaces with a predetermined distance between the bottom and top surfaces of the gear and the inner circumferential surface of the coil. After heating the tooth bottom so that the temperature is higher than the tooth tip, the tooth surface and the tooth tip are heated along the tooth profile while heating the tooth bottom, and then +c+ from the coolant injection hole. The coolant is injected toward the bottom of the tooth and along the two protruding surfaces, thus hardening the tooth along the tooth profile (4.i:i 9B).

That is, according to the present invention, the inner circumferential surface of the coil is shaped to follow the tooth shape of the mountain by providing the inner circumferential surface of the coil I-1 with knee-square protrusions in the form of internal teeth, and the triangular protrusions A high frequency current is applied from the tip, and the tooth bottom of the gear is induced by 4.1, which is 7, and the crest and the end are also added to make it 1-.

In the present invention, first, the bottom of the tooth of the float is lj':l ;! from 1'Ui ahead. HA, l After heating the bottom of the tooth so that it becomes brocade, harden the crest surface and tip along the mountain shape while heating the tooth bottom! l, lAA ++; H' (to add color) , annular high-frequency 1E flow; A protrusion having a predetermined distance of h, 1 is inserted between the tooth bottom surface, a ridge portion, and a tooth top surface, and a predetermined high-frequency current is applied to the coil for a predetermined period of time.

In general, when induction hardening the peak i1J, when nailing the seven wheels of the gear with Ill, the formula for setting the appropriate frequency f is f = 6 x l O
'/n((llz) is known, and the cyclic ring A'J-J
JI+) If the high frequency 1E current of the appropriate frequency determined according to the gear module is applied to the coil as described above, the entire bottom crest of the gear from the d°1 tip is uniformly heated. When a high frequency current with a frequency higher than the appropriate frequency specified in J4 is applied, the tooth tips and crests are heated, resulting in
The hardened layer on the tooth tip and tooth surface becomes thicker, and the hardened layer on the tooth bottom becomes thinner.

On the other hand, if a lower frequency than the appropriate frequency J is used, the entire crest and the tooth bottom are heated, and as a result, the crest is heated to a higher temperature than the tooth tip, and the hardened layer at the tooth bottom becomes I! /-, but the entire tooth portion is hardened.

Therefore, in the method of the present invention, a triangular protrusion is provided on the inner circumferential surface of the coil so that the inner circumferential surface of the coil follows the tooth profile of the gear, and as described above, the frequency of the high-frequency current is lower than the appropriate frequency. By heating the base of the crest to a higher temperature than the tip of the tooth, and at the same time, by appropriately selecting the distance between the inner circumferential surface of the coil having the triangular protrusions and the gear, the gear can be heated as a whole. It is contour hardened.

In other words, if the distance between the inner circumferential surface of the coil and the gear is too small for the tooth bottom and tooth surface, the tooth bottom will be heated before the tooth tip, but this will be explained later) Cooling Its
! ζ1)Y and 4ζ
The first one is born from Eisamura. - When the float is heated by induction, the top surface and tip are heated earlier than the Ti bottom, and the bottom of the tooth is not heated, so the hardened layer at the bottom of the tooth is shallow. Become. Therefore, the distance between the inner circumferential surface and the tooth bottom and mountain surfaces is 0.3 to 1.OL (
Tooth thickness) is preferred. In addition, at the base of the crest, if the distance from the inner circumference curve of the 22nd wheel is too small, the tip of the tooth will be cut earlier than the bottom of the tooth, and the entire crest will be added (-) evenly. 1-KimonN, when the gargle is injured, the outlet is not added.i'L, between the outlet surface and the inner circumferential surface of the coil 1ζ"j is 2.0 to 3.510 (
−υ Joule) is preferred.

Furthermore, the heating time by the high frequency jL flow is also important.

If the addition time is too long, the entire crest is hardened by the force U ;, the entire ridge is hardened by the subsequent 9 cooling steps, and if the addition time is too short, the quenching temperature IW is applied.
♀, no. Generally, the heating time is preferably in the range of 0.5 to 1 second.

In the present invention, as described below, the inner circumferential surface of the coil is shaped to follow the tooth profile of the gear, and the frequency of the high-frequency current used, the inner circumferential surface of the teeth 41 and 21, After heating the tooth bottom to a higher temperature than the tooth tip by properly selecting the interval and heating time, heat the tooth surface and tip along the tooth profile while heating the tooth bottom, and then The coolant is injected from the coolant injection hole LJ installed in the groove between the triangular projections toward the tooth bottom and along the projection surface.As in the conventional 4J, the inner surface of the coil forming a circumferential surface The coolant may be injected in the radial direction of the gear, or as described in 11:I, the coolant may be injected from the inner peripheral surface formed in a corrugated shape in the normal direction to the gear. According to the method of cooling the gear, it is difficult to harden the gear uniformly, especially at the bottom of the tooth.However, by applying the method of the present invention, it is difficult to harden the gear evenly. With the triangular protrusion inserted, the coolant is directed toward the bottom of the tooth and along the two protrusion surfaces, as shown in the section in Fig. 2.
A hardened layer 4 having a uniform depth and hardness is formed on the tooth bottom 2, crest 3, and tooth tip 1.

In addition, even when cooling with this coolant, the coil inner circumference I
[The distance between +i and the center of the tooth is important; if the distance between the bottom and the top of the tooth is too small, the flow of coolant toward the bottom of the tooth will not be good, especially if the bottom is hardened or not. minutes, so it is preferable to set the interval within the range described above.

Next, the −C quotient 1hj wave induction addition that is preferably used in the method of the present invention described in 1. (Ichikawa Go Il-
・Examples are shown in Figures 3 to 1 to 5. This:Ji/1-
11 is mountain 11 (the combination of mountain 11゛1 and l'Dt-?),
1. A sea urchin angle jC-shaped protrusion 12 on the circumferential surface 11! At the same time, the J skin part 13 (1,, is the bottom 2 of the tooth in the mountain) between the protrusions.
1-11C, open the cold JJI agent as shown in the illustration. t The BJ hole 14 is numbered J. On the first lap of the evening, there are 711 cooling punishment Sendai 1''i! and Toride 15 is Toride 4 = JU and IIC.

According to the method of the present invention, according to the method of the present invention, the floats are
B quenching 4+, the hardening is hard, and the hardened layer has uniform hardness and
1' The diameter is f1, the entire crest is not hardened, the crest has high toughness, and the fatigue resistance is excellent, making it particularly suitable for manufacturing small high-strength tooth shapes up to about -L Joule 4. be.

The present invention will be explained below with reference to 74 Examples, but how can the present invention be understood by these Examples? Nothing is limited to il et al.

Example As shown in Fig. 3: 1 coil was used, and the distances between the inner circumferential surface of the 2 J coil and the tooth bottom surface and the tooth surface were set to 1, 5 m@ and 2 brocades, respectively, and the inner circumferential surface of the coil was set to 1. The distance from the delivery surface is 7.
As a dragon, a spur gear with module 2.5 (optimal frequency approx. 1
00 KII2), frequency 40 K11z, voltage 12K
V, current 16.5 A, heating time 0.77-0.81 (
, v (after high-frequency heating in '1), 3% Solipul was sprayed as a coolant for 3 to 4 seconds from the injection hole between the protrusions toward the tooth bottom, ζ, and parallel to the protrusion surface. , quenched and hardened.

Figure 6 shows the results of examining the hardness of each part of the tooth tip, tooth surface, and tooth bottom.Each part is hardened to a uniform hardness of 1 minute. In the 21st section, the sea urchin is cut into 7 pieces, and the sea urchin is cut along the chevron.

IL Comparative Example 1 Example 1/1: 49゛C1 frequency 150Kllz,
Voltage 1 (l K V ,'+'J1L): Mouth (I A
, Kai! ; Li lit (except for 1.8 seconds Toshita,
The inside of L-(+'1.) was induction hardened on the same surface. tl:
1 bottom LJ) ahead? The crests and tooth surfaces were heated, the hardened layer at the crest was bent by 1 inch, and the hardened layer at the bottom was peeled off.

: 1 - If the frequency L'< 1O11 or 211 or more IJ and L2, 6 passes, '1' or i'+': When it becomes (t, the addition time is also long... 7.,..., the mountain part was hardened).

[Brief explanation of the drawing]

Figure 1 shows a tooth 11 that has been light hardened using the traditional method.
Bow-11 (j, -1 hardening 11・j, 1-5, 21st
Fig. 1 shows the hardened layer of 1, S, I'2, S'lX quenched J1 and Yamanaka in the method of the present invention; Fig. 4 is a perspective view showing the main part of the inner circumferential surface of the coil, and Fig. 5 is a main part 111i showing the positional relationship between the inner circumferential curve and the gear. Top view, 61st page 1 is a graph showing the relationship between the hardness and the distance P, 1] from the surface of the gear contour hardened by the method of the present invention. ■... Tooth tip, 2...・Tooth bottom, 3...Tooth surface, I...
Hardened layer, 11... Coil, 12... Diagonal protrusion,
]3...Bottom, J4...coolant injection hole. Fig. 1 t52 Fig. 5 Fig. 5 ()l'<1 oldωri)

Claims (1)

[Claims] (1) Place a gear inside a single-mouth high-frequency induction heating coil.
In the induction hardening method for floats, the coolant is injected into the gear from the coolant injection hole. After removing the gap, insert the diagonal protrusion formed on the inner circumferential surface of the coil between the ridges, and heat the bottom of the tooth so that the hot water temperature is 1', ii, higher than that of the tip. After L7, heat the tooth surface and tooth tip along the tooth profile while heating the tooth bottom, then tel 7'8 JA'Ha11 1;1 from the injection hole to the tooth bottom.
1. A method for induction hardening of gears, characterized in that a ζ coolant is injected along the protrusion surface in one step and along the angular shape for contour hardening.