JPH048489B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to gears M2 to M6 of small modules, for example.
On the other hand, in order to obtain a hardening pattern that is almost comparable to the hardened layer obtained by the carburizing hardening method, there is a method of contour hardening the gear in an atmospheric gas by induction hardening, especially high-frequency bright hardening, or high-frequency non-oxidation hardening. , relates to an apparatus for applying the method to gears.

BACKGROUND ART Conventionally, in order to harden the surface of a gear by induction hardening, an annular coil is used that is placed around the tooth tip of the gear so as to face the tooth tip. Contour Hardening of gears
As shown in FIG. 6a, in a gear 100 having a plurality of teeth 101,
2. This means that the thickness t of the hardened layer 105 is formed to be substantially constant on both the tooth side surface 103 and the tooth bottom 104.

Problems to be Solved by the Invention However, when using the conventional surface hardening method, it is difficult to form a hardened layer 105 with a substantially constant thickness as shown in FIG. 6a.
Different curing patterns result. For example, as shown in FIG. 6b, the thickness of the hardened layer 105 gradually increases from the tooth bottom 104 to the tooth tip 102 via the tooth side surface 103, or
As shown in Figure c, a hardened layer 105 is applied to the entire tooth 101
is formed, and the surface to be hardened is oxidized because it is hardened in air. When such a hardened layer 105 is formed, the teeth 101 become brittle and the gear 100 becomes brittle.
When an impact is applied to the tooth 101, the tooth 101 may be damaged.

The present invention has been made in view of the above,
Atmosphere chamber with interconnected preliminary chamber and heat treatment chamber (approximately U-shaped in cross section, the lower open part is buried in the coolant level, and the liquid level and the closed part with approximately U-shaped cross section separate the indoor and outdoor areas. An exhaust port is provided in the preliminary chamber and heat treatment chamber to discharge the atmospheric gas introduced into the preliminary chamber and the heat treatment chamber, and the workpiece is heated in the atmosphere entering the preliminary chamber and inside the heat treatment chamber. The gas generated by this process is replaced with atmospheric gas, and by induction hardening, the tooth tip, tooth side surface, and tooth bottom of the gear have almost uniform thickness, and the gear is treated in the atmospheric gas. Therefore, it is an object of the present invention to provide a so-called bright contour hardening method capable of forming a hardened layer having a bright tooth surface, and an apparatus for applying the method to a gear.

Means for Solving the Problems In order to solve the above problems, the method of high-frequency bright contour hardening of gears in an atmospheric gas of the present invention involves introducing the gears into a preliminary chamber filled with a non-oxidizing or reducing gas. a step of transporting the gear into a heat treatment chamber filled with the gas, preheating the gear in the heat treatment chamber and then main heating it, and cooling the main heated gear and removing it from the heat treatment chamber. and a step of unloading, and the step is automatically and continuously performed.

In addition, the apparatus for bright high-frequency contour hardening of gears in an atmospheric gas according to the present invention includes a preliminary chamber for replacing air with a non-oxidizing or reducing gas, and a preliminary chamber that is connected to the preliminary chamber and is filled with the gas. A heat treatment chamber having a means for preheating and a means for main heating, a cooling means for cooling the heated gear, and a moving means for holding the gear and moving it between the preliminary chamber, the heat treatment chamber, and the cooling means. ing.

Action The gear revolves by means of movement, and the shutter S ₁
(Shutter S ₂ is closed at this time), the atmosphere is brought into the reserve chamber, and the atmosphere that entered the reserve chamber is replaced by the incoming gas, and the gear is completely isolated from the atmosphere. When the shutter S ₂ is opened and closed (at this time, the shutter S ₁ is closed), the gear is carried into the heat treatment chamber and begins to rotate by the moving means, and is preheated by the preheating coil, and the rear gear is moved to the heating coil position. It rises and is heated by the heating coil. After the main heating, the cooling liquid is sprayed and cooled from the heating coil.

The gear is then lowered by the moving means into the immersion cooling liquid for further cooling. After this, the gear stops rotating and continues to revolve in the coolant.

Once cooling in the coolant is complete, the gear is raised above the coolant level and then replaced with a green gear.

Embodiment FIGS. 1 to 4 show an embodiment of the present invention, and FIG. 1 is a diagram illustrating the operation of a high-frequency bright contour hardening device for hardening gears by a high-frequency bright contour hardening method. Figure 2a is a plan view of the device, Figure 2b is a front view of the device, and Figure 3 is a schematic diagram of the device developed linearly.
The figure is a perspective view of the preheating coil, Figure 4a is a plan view of the heating coil and workpiece, and Figure 4b is A of Figure 4a.
- A cross-sectional view and a partial cross-sectional view of the workpiece mounting section are shown, respectively.

This high frequency bright contour hardening device is
A preliminary chamber 10 with an open bottom and shutters S ₁ and S ₂ installed at both ends, and a heat treatment chamber 20 with an open bottom that is connected to the preliminary chamber 10 via shutter S ₂ .
Then, the gear that is the workpiece W is placed in the preliminary chamber 10,
It has a moving means 40 that moves between the heat treatment chamber 20 and the cooling means 30.

The heat treatment chamber 20 is formed in a substantially semicircular arc shape as shown in FIG. It is divided into.

The moving means 40 includes a turntable 42 provided with a workpiece placement part 41 (41 ₁ to 41 ₁₂ ) on which a gear, which is a workpiece W, is placed, and a main heating quenching zone 22 of the heat treatment chamber 20 and a preliminary chamber 10 . The workpiece mounting section 41 is heated with cooling liquid at the middle of
a first cylinder 43 that is raised from the liquid level of _L2 ;
Main heating quenching zone 22 (first
The second cylinder 44 moves the workpiece mounting section 41 up and down at a position of 210 degrees in the figure (FIG. 2b). However, the position of the workpiece placement part 411 shown in FIG. _2a is set as the 0° position, which is the reference point for the rotation of the turntable 42, and this 0° position coincides with the 0° position in FIG. ing.

A gas supply means 50 is connected to the preliminary chamber 10 and the heat treatment chamber 20 for supplying a non-oxidizing gas G such as nitrogen or argon or a reducing gas G such as hydrogen as an atmospheric gas. Furthermore, gas exhaust ports 51 and 52 for discharging the supplied gas G are provided in the ceilings of the preliminary chamber 10 and the heat treatment chamber 20, respectively.

The preheating zone 21 of the heat treatment chamber 20 (from the 90° position to the 180° position in Fig. 1) has an approximately 1/4 arc shape as shown in Fig. 3 to accommodate the movement of the workpiece W to be preheated. The tunnel-shaped preheating coil 23 formed in
At the 210° position, substantially circular heating coils 24 as shown in FIG. 4 are installed. The preheating coil 23 and the heating coil 24 are equipped with high frequency power supplies 23a and 24a shown in FIG. 2a, respectively.
A high frequency current is supplied from the Note that the heating coil 24 is formed with an injection hole 24a for injecting the cooling liquid.

The moving means 40 is a so-called Geneva mechanism, and includes a turntable 42 that rotates intermittently in the direction of arrow A shown in FIG. 2A by a turntable rotation mechanism (not shown), and this turntable 4
1. Twelve workpiece mounting portions 41 (41 ₁ to 41 ₁₂ ) are vertically movably installed on 2. That is, this workpiece mounting section 41 is placed on the turntable 42 at intervals of 30 degrees when viewed from the center of the turntable 42.
They are installed concentrically around the upper surface of the . Further, the turntable 42 intermittently advances by one step at intervals of about 15 seconds, and the turntable 42 rotates 15 degrees with each step. That is, the turntable 42 rotates once in 24 steps. As the turntable 42 rotates, the workpiece W placed on the workpiece placement section 41 revolves.

Furthermore, in order to uniformly preheat, main heat, and injection cool the workpiece W, a workpiece rotation means 45 for rotating the workpiece W in the preheating zone 21 and the main heating and quenching zone 22 is provided along the edge of the turntable 42. ing. This work rotation means 45 is 9
In FIG. 1, the workpiece mounting section 41 at each step position is rotated from a position of 90 degrees to a position of 210 degrees or less. In FIG. 2b, only the workpiece rotation means 45 for rotating the workpiece mounting portion ₄₁₈ located at the 210° position in FIG. 1 is shown as a representative.

The cooling means 30 is composed of a cooling liquid L ₁ injected from the heating coil 24, a tank 31, and a cooling liquid L ₂ in this tank. The lower end portions of the side surfaces of the preliminary chamber 10 and the heat treatment chamber 20 are immersed in the cooling liquid _L2 . Further, the turntable 42 to which the workpiece placement section 41 is attached is installed in the cooling liquid _L2 , and as described above, the turntable 42 is attached to the first cylinder 43.
and the second cylinder 44, each workpiece placement section 4
1 appears above the liquid surface of the coolant _L2 or sinks below the liquid surface.

Next, the operation of this embodiment will be explained with reference to FIGS. 1a to 1j. In addition, in the drawings from b onward in FIG. 1, the gas supply means 50, the heating coil 24, etc., the preheating zone 21, and the main heating and quenching zone 22 are not shown. In addition, the scales from 0° to 360 _° at 15° intervals shown in FIGS.
0° corresponds to positions sequentially selected at a pitch of 15° in the direction of the arrow A. In addition, the first
In figures b to d, f to h and j, the scale from 0 to 360° is omitted. Further, gas G is constantly supplied to the preliminary chamber 10 and the heat treatment chamber 20 from the gas supply means 50, and the supplied gas G is discharged from the discharge ports 51 and 52. The preheating coil 23 and the heating coil 24 are provided with high frequency power supplies 23a and 24, respectively.
A high frequency current is supplied from a.

The following will mainly describe operations that occur as the workpiece placement section 41 ₁ moves.

The work W ₁ is placed on the work placement section 41 ₁ at the 0° position. At this time, the workpiece placement parts 41 ₂ to 41 ₁₂
No workpiece W is placed therein, the workpiece placement portion 41 ₁₂ is placed in the preliminary chamber 10 , the workpiece placement portion 41 ₁₁ is placed in the heat treatment chamber 20 , and the workpiece placement portions 41 ₁₀ to 41 _{7 are} placed in the heat treatment chamber 20 .
is in the preheating zone 21 in the heat treatment chamber 20, the workpiece placement part ₄₁₆ is in the main heating quenching zone 22 (in the cooling liquid _L2 at the bottom of this zone), and the workpiece placement part ₄₁₅ to
41 ₄ is a workpiece mounting portion 41 ₃ to 41 in cooling liquid L ₂ .
₂ rises above the level of the coolant L ₂ and is in the atmosphere (Figure 1a).

Next, shutter S ₂ is opened and turntable 4 is opened.
When step 2 advances by one step, the workpiece mounting section ₄₁₁ reaches just before the preliminary chamber 10, the workpiece mounting section ₄₁₁₂ enters the heat treatment chamber 20, and the shutter _S2 closes. During this time, the shutter _S1 is in a closed state (FIG. 1b).

In the next step, the shutter S ₁ opens, the workpiece mounting section 41 ₁ reaches the preliminary chamber 10, and the shutter S ₁ opens.
closes. During this time, shutter _S2 remains closed. The air that has flowed into the preliminary chamber 10 is replaced by the gas G. Workpiece placement section 4 has reached the 0° position
A workpiece W ₂ is placed on 1 ₂ (Fig. 1c). below,
A workpiece W is placed on the workpiece placement section 41 that sequentially comes to the 0° position each time.

In the next step, the shutter S ₂ opens, the workpiece mounting section 41 ₁ enters the heat treatment chamber 20 (45° position) in a state where it is completely cut off from the atmosphere, and the shutter S 2 opens.
S ₂ closes. Further, the workpiece W ₂ comes to a position in the atmosphere (at a position of 15°) just in front of the preliminary chamber 10 (FIG. 1d).

Thereafter, after three steps have passed, the workpiece mounting portion 41 ₁ reaches the 90° position, that is, reaches the preheating zone 21, and the workpiece W ₁ is heated by the preheating coil 23 supplied with high frequency current from the high frequency power source 23a. Preheating starts. Further, since the workpiece rotation means 45 rotates the workpiece mounting portion 41 ₁ , the workpiece W ₁ also starts to rotate (FIG. 1e).

As the steps progress, the workpiece W ₁ rotates within the preheating zone 21 and sequentially revolves in a stepwise manner, thereby continuing to be preheated (FIG. 1f).

When the workpiece mounting section 41 ₁ reaches the 210° position, that is, the main heating hardening zone 22, the workpiece mounting section 41 ₁ is raised by the second cylinder 44, and the workpiece W ₁
is introduced into the heating coil 24. Next, a high frequency current is supplied from the high frequency power source 24a to the heating coil 24 to perform main heating, and then the heating coil 2
4, the cooling liquid L ₁ is injected onto the workpiece W ₁ to perform injection cooling. Next, the workpiece mounting portion ₄₁₁ is submerged in the cooling liquid _L2 by the second cylinder 44, and immersion cooling of the workpiece _W1 is started (FIG. 1g).

In the next step, the workpiece _W1 that has exited the main heating and hardening zone 22 stops rotating after that position (225° position), and continues to be cooled by successively passing through the cooling liquid _L2 (the first Figure h).

When the workpiece mounting portion 41 ₁ reaches the 300° position, the first cylinder 43 causes the workpiece mounting portion 41 ₁ and therefore the workpiece W ₁ to rise above the liquid level of the cooling liquid L ₂ (first Figure i).

Next, the workpiece mounting section 41 ₁ reaches a position of 330°,
Workpiece W ₁ is removed (Fig. 1j). After this,
Workpieces W are sequentially removed from the workpiece mounting portion 41 that comes to the 330° position.

As described above, the workpiece W ₁ is placed on the workpiece mounting section 41 ₁
After being placed on the workpiece W ₁ , a cycle of preheating, main heating, injection cooling, and immersion cooling is automatically and continuously performed on the workpiece W 1 , and then the workpiece W ₁ is removed from the workpiece placement section 41 ₁ . removed.

When the workpiece placement section 41 ₁ reaches the 0° position, the unhardened workpiece is placed in the same way as the beginning, and the
The above cycle is repeated.

The above is mainly about the operation of the workpiece mounting section 41 ₁ ,
The operation of the workpiece W ₁ placed on this workpiece placement section has been explained, but the workpiece placement sections 41 ₂ to 42
₁₂ and the work W ₂ placed on these work placement parts
The operation of ~ _W12 is similar.

In this embodiment, there are 12 workpiece placement sections, but the number is not necessarily limited to 12, and the number of workpiece placement sections can be selected as appropriate.

FIG. 5 is a graph showing the measurement results of the hardness distribution of the gear induction hardened according to this example,
The horizontal and vertical axes represent the depth (mm) and hardness (Hv) from the tooth surface, respectively.
5b shows the hardness distribution at the tooth bottom, and FIG. 5b shows the hardness distribution at the tooth tip. Note that curves 51 and 53 show the hardness distribution when preheating is performed, and curves 52 and 54 show the hardness distribution when preheating is not performed.

The specification data of the gear used for this measurement is as follows.

Module 3.5 Number of teeth 28 Teeth Width 20mm Pressure angle 20゜ Inner diameter 20mm Outer diameter 105mm Steel type S45C Quenched surface area Approx. 120cm ² Hardness during pre-heat treatment (both quenching and tempering)
Preheating, main heating and cooling conditions when Hv250 curves 51 and 53 are obtained are as follows.

Preheating conditions Frequency 10kHz or less Preheating temperature 200 to 650℃ Main heating conditions Frequency 10 to 100kHz Input 330kW Heating time 0.6 seconds Cooling conditions Injection refrigerant UQA11%, 30℃, 70/min Immersion refrigerant UQA11%, 30℃ Cooling time Injection cooling 5 seconds + immersion cooling time When the effective depth of the hardened layer is defined as the range in which the hardness of the hardened layer formed on the gear is Hv450 or higher, the effective depth of the hardened layer is
The result is as follows (units are mm).

Tooth root Tooth tip With preheating 0.8 1.25 Without preheating 1.25 6.8 The above results show that when the gear is hardened according to this example, the tooth bottom, tooth tip, and therefore also the tooth side surface are In addition to showing that good contour hardening can be obtained, the effective depth of the hardened layer, especially at the tooth tip, can be improved by preheating and by the influence of the amount of heating power (and by extension, the heating time). It can be seen that there is a noticeable difference in the

Effects of the Invention As explained above, according to the high frequency contour hardening method for gears of the present invention and the high frequency contour hardening device using this contour hardening method, the gears are heated by non-oxidizing or reducing gas. The process includes a step of transporting the gear into a pre-chamber filled with gas, a step of transporting the gear into a heat treatment chamber filled with this gas, preheating it and then main heating it, and a step of cooling the main heated gear and transporting it out of the heat treatment chamber. Moreover, since these steps are performed automatically and continuously, there is an advantage that good contour hardening can be performed on the gear.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, and FIG. 1 is a schematic diagram illustrating the operation of a high-frequency contour hardening device for hardening gears by a high-frequency contour hardening method. Figure a is a plan view of this device, Figure 2 b is a front view of this device, Figure 3 is a perspective view of the preheating coil, Figure 4 a is a plan view of the heating coil and workpiece, and Figure 4 b is the fourth
A sectional view taken along the line AA in Figure a and a sectional view of a part of the workpiece mounting section are shown, respectively. FIG. 5 is a graph showing the measurement results of the hardness distribution of the gear induction hardened according to this example,
Figure 5a shows the hardness distribution at the tooth bottom, and Figure 5b shows the hardness distribution at the tooth tip. FIG. 6 shows various hardened layer patterns formed on gears. DESCRIPTION OF SYMBOLS 10...Preliminary chamber, 20...Heat treatment chamber, 21...Preheating zone, 22...Main heating quenching zone, 23...Preheating coil, 24...Heating coil, 30...Cooling means, 40...
Moving means, 41... Work placement part, 42... Turntable, 43... First cylinder, 44... Second cylinder, 45... Work rotation means, G... Non-oxidizing or reducing gas, S ₁ , S ₂ ... Shutter , W...Work.

Claims (1)

[Claims] 1. Carrying the gear into a preliminary chamber filled with a non-oxidizing or reducing gas, carrying the gear into a heat treatment chamber filled with the gas, and preheating the gear in the heat treatment chamber. and a step of cooling the fully heated gear and carrying it out from the heat treatment chamber, and the step is automatically and continuously carried out in an atmosphere gas of the gear. High frequency contour hardening method. 2. A preliminary chamber filled with a non-oxidizing or reducing gas, a heat treatment chamber connected to the preliminary chamber and filled with the gas, and having means for preheating the gear and means for main heating the gear, and a heated gear. 1. An apparatus for high-frequency contour hardening of gears in atmospheric gas, comprising a cooling means for cooling the gear, and a moving means for holding the gear and moving it between the preliminary chamber, the heat treatment chamber, and the cooling means.