JP5713172B2 - Induction hardening method - Google Patents

Description

  The present invention relates to an induction hardening method, and more particularly to a method of moving and quenching an inner surface portion of a cylindrical member.

  The inner surface moving quenching method is known as means for efficiently induction-hardening the inner surface portion of the inboard cup of a constant velocity joint, for example. For example, the inner surface moving quenching apparatus described in Patent Document 1 is configured by connecting a cooling jacket to a high frequency heating coil. The inboard cup is fixed coaxially with respect to the quenching apparatus with the mouth facing downward. In this state, the quenching device is moved upward in the axial direction so that the quenching device is inserted into the inboard cup and positioned at the quenching start position. Next, the quenching apparatus is moved at a constant speed. At this time, a high-frequency current is applied to the high-frequency heating coil, and the coolant is sprayed from the cooling jacket toward the inner surface of the inboard cup. As a result, the inner surface of the inboard cup is heated from the mouth toward the back, and the heating surface (the inner surface of the inboard cup) is rapidly cooled by the coolant, so that the inner surface of the inboard cup is moved from the mouth to the back. It is quenched sequentially.

  By the way, in the conventional induction hardening (inner surface transfer hardening) method, the inner surface of the inboard cup is induction hardened from the mouth to the back at a constant moving speed and output. Heating and cooling proceed sequentially from the mouth of the cup to the back. Therefore, the amount of heat input at the back of the inner surface portion of the inboard cup is substantially larger than the amount of heat input at the mouth, and the inboard cup after quenching tends to shrink more deeply than the mouth. As a result, the width of the roller groove that requires strict dimensional tolerances is tapered, that is, the inboard cup tapers from the mouth to the back, and the inboard cup, particularly the inboard cup, There has been a demand for improving the accuracy of the roller groove width.

Japanese Patent Laid-Open No. 10-324914

The present invention has been made in view of the above circumstances and provides induction hardening method capable of ensuring the accuracy of the groove width of the roller grooves of the inboard cup is induction hardening by the inner surface moving quenching It was made as an issue.

In order to solve the above problems, the induction hardening method of the present invention is a method in which a roller groove extending in the axial direction provided on the inner surface portion of the inboard cup of the constant velocity joint is induction hardened by an inner surface moving hardening method. there are, to set the heat input to the inboard cup when induction hardening at a constant heat input from the mouth of the inboard cup deep into standard heat input was increased to the standard heat input A first quenching step of quenching the mouth side of the inboard cup with a first heat input, and a second quenching of the back side of the inboard cup with a second heat input reduced with respect to the standard heat input. and 2 hardening step, only contains the first heat input is 3.5 to 4.0 times said second amount of heat input, from the mouth of the inboard cup of the axial length of the roller grooves When the quenching has progressed to 1/3, the first firing Step from and wherein the switching to the second quenching step.

(Aspect of the Invention)
In the following, aspects of the invention that is recognized as being capable of being claimed in the present application (hereinafter referred to as claimable invention) will be exemplified, and each exemplified aspect will be described. Here, as in the claims, each aspect is divided into paragraphs, numbers are assigned to the respective paragraphs, and the descriptions of other paragraphs are cited as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combination of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiment, etc., and as long as the interpretation is followed, another aspect is added to the aspect of each section. Moreover, the aspect which deleted the component from the aspect of each term can also be one aspect of the claimable invention.
In the following items, each of the items (1) to ( 3 ) corresponds to each of claims 1 to 3 described in the claims.

(1) an inner surface portion roller groove extending in the axial direction provided on the inboard cup of the constant velocity joint to a method of induction hardening by the inner surface movement sintered Iriho, constant from the mouth of the inboard cup deep entrance The amount of heat input to the inboard cup when induction hardening with heat is set to the standard heat input, and the first side of the inboard cup is quenched with the first heat input increased with respect to the standard heat input. and quenching steps, viewed contains a second quenching step of quenching the back side of the inboard Cup second heat input was reduced relative to standard heat input, the first heat input and the second heat input From the first quenching step to the second quenching step when quenching has progressed from the mouth of the inboard cup to 1/3 of the axial length of the roller groove. Induction hardening method to switch .
The inner surface of the inboard cup constant velocity joint, by a conventional inner surface movement sintered Iriho, when induction hardening at a constant moving speed and output, sequentially heating and cooling toward the mouth of the inboard cup to the back progress Therefore, the heat input at the back of the inboard cup is substantially larger than the heat input at the mouth. Therefore, the inboard cup after induction hardening tends to contract more greatly at the back than the mouth. As a result, the groove width of the roller groove, which requires particularly strict dimensional tolerance in the inboard cup, is deformed into a tapered shape, that is, a tapered shape from the mouth to the back.
Therefore, in the induction hardening method described in this section, the mouth side of the inner surface portion of the inboard cup of the constant velocity joint is placed at the standard heat input, that is, the inner surface of the inboard cup is heated at a constant heat input from the mouth to the back. Set the default heat input amount in the conventional induction hardening method for quenching to the standard heat input amount, and furthermore, the shrinkage amount of the hardened part in the inner surface part of the inboard cup is substantially equal at the mouth and back, The first heat input increased with respect to the standard heat input and the second heat input decreased with respect to the standard heat input are set. In the first quenching step, the mouth side of the inboard cup is set to the first heat input. In a second quenching step that is induction-quenched with the amount of heat input and is continuous therewith, the back side of the inboard cup is induction-quenched with the second amount of heat input.
Therefore, in the conventional induction hardening method (the amount of heat input is constant), the groove width of the roller groove of the inboard cup tends to open from the back to the mouth, but in the aspect of this section, By adjusting the first heat input amount and the second heat input amount so that the shrinkage amount at the mouth and the shrinkage at the back are substantially equal, the opening from the back to the mouth in the groove width of the roller groove is suppressed. As a result, a dimensional tolerance of the groove width of the roller groove can be ensured.
Further, based on an empirical law, the first heat input (Q1) in the first quenching step is 3.5 to 4.0 times the second heat input (Q2) in the second quenching step (Q1 = Q2 × 3.5 to 4.0), the shrinkage at the mouth and the shrinkage at the back of the hardened portion of the inner surface portion of the inboard cup can be made substantially equal. As a result, the groove of the roller groove The opening from the back to the mouth in the width can be effectively suppressed.
It should be noted that the heat input amounts in the first quenching step and the second quenching step are Q1 and Q2, the outputs of the induction hardening apparatus in the first quenching step and the second quenching step are W1 and W2, the first quenching step and When the relative movement speed between the induction hardening apparatus and the inboard cup in the second quenching step is V1 and V2, and C is a default value,
Q1 = (W1 / V1) × C
Q2 = (W2 / V2) × C
Can be expressed as here,
Since Q1 / Q2 = 3.5 to 4.0, after all,
(W1 × V2) / (V1 × W2) = 3.5 to 4.0: (Formula 1)
What is necessary is just to set the output W1 and moving speed V1 of the hardening apparatus in a 1st hardening step, and the output W2 and moving speed V2 of a hardening apparatus in a 2nd hardening step so that it may satisfy | fill.
Further, based on empirical rules, the switching position from the first quenching step to the second quenching step is such that the axial distance from the mouth of the inboard cup is 1 of the axial length (full length) of the portion to be quenched. The position is set to / 3. Thereby, the opening from the back to the mouth in the groove width of the roller groove can be suppressed, and as a result, the dimensional tolerance of the groove width of the roller groove can be ensured.
And in the constant velocity joint assembled with the inboard cup obtained in this way, it becomes possible to greatly reduce the backlash between the roller and the roller groove as compared with the conventional induction hardening method. In addition, noise and vibration while the vehicle is running can be reduced, and the comfort of the vehicle can be improved.

( 2 ) The relative movement speed between the induction hardening device and the inboard cup is set to the standard movement speed when the induction hardening is performed at a constant movement speed from the mouth to the back of the inboard cup , In the first quenching step, the mouth side of the inboard cup is quenched at the first moving speed reduced with respect to the standard moving speed, and in the second quenching step, the mouth is moved with respect to the standard moving speed. The induction hardening method according to (1), wherein the back side of the inboard cup is quenched at the increased second moving speed.
In the induction hardening method described in this section, the mouth side of the inner surface of the inboard cup is induction hardened at a standard moving speed, that is, the inner surface of the inboard cup is induction hardened at a constant moving speed and output from the mouth to the back. The default moving speed in the induction hardening method is set to the standard moving speed, and the standard moving speed is set so that the shrinkage of the hardened part on the inner surface of the inboard cup is approximately equal between the mouth and the back. The first moving speed decreased with respect to the standard moving speed and the second moving speed increased with respect to the standard moving speed are set, and in the first quenching step, the mouth side of the inboard cup is set to a high frequency at the first moving speed. In the second quenching step after quenching, the inner side of the inboard cup is induction-hardened at the second moving speed.
Therefore, in the conventional induction hardening method (moving speed and output are constant), the groove width of the roller groove of the inboard cup tends to open from the back to the mouth. By adjusting the first movement speed and the second movement speed so that the shrinkage amount at the mouth of the entrance and the shrinkage at the back are substantially equal, the opening from the back to the mouth in the groove width of the roller groove is made. As a result, it is possible to ensure a dimensional tolerance of the groove width of the roller groove. In addition, in the constant velocity joint with the inboard cup obtained in this way, it becomes possible to greatly reduce the backlash between the roller and the roller groove as compared with the conventional induction hardening method. In addition, noise and vibration while the vehicle is running can be reduced, and the comfort of the vehicle can be improved.
In the aspect of this section, in the above (Formula 1),
Since W1 = W2, by substituting this into (Equation 1),
V2 / V1 = 3.5 to 4.0: (Formula 2)
Can be obtained. That is, V1 and V2 may be set so as to satisfy the above (Formula 2). However, (Formula 2) is one measure in the aspect of this section, and what is important in the aspect of this section is to satisfy the above (Formula 1).

( 3 ) Set the output of the induction hardening apparatus to the standard output when induction hardening is performed at a constant output from the mouth of the inboard cup to the back, and increase in the first hardening step relative to the standard output. the mouth-side of the inboard cup first output is then hardened, the second quenching step, quench the far side of the inboard Cup second output with reduced relative to the standard output (1) induction hardening methods.
In the induction hardening method described in this section, the mouth side of the inner surface of the inboard cup is subjected to induction hardening at a standard output, that is, the inner surface of the inboard cup is induction hardened at a constant moving speed and output from the mouth to the back. The default output in the induction hardening method is set to the standard output, and further, the shrinkage of the hardened part on the inner surface of the inboard cup is increased with respect to the standard output so that the shrinkage amount is almost equal between the mouth and the back. The first output and the second output reduced with respect to the standard output are set, and in the first quenching step, the mouth side of the inboard cup is induction-hardened with the first output and is continuously continuous. In the second quenching step, the back side of the inboard cup is induction hardened with a second output.
Therefore, in the conventional induction hardening method (moving speed and output are constant), the groove width of the roller groove of the inboard cup tends to open from the back to the mouth. By adjusting the first output and the second output so that the amount of contraction at the mouth of the entrance portion and the amount of contraction at the back are substantially equal, the opening of the roller groove from the back to the mouth is suppressed. As a result, a dimensional tolerance of the groove width of the roller groove can be ensured. In addition, in the constant velocity joint with the inboard cup obtained in this way, it becomes possible to greatly reduce the backlash between the roller and the roller groove as compared with the conventional induction hardening method. In addition, noise and vibration while the vehicle is running can be reduced, and the comfort of the vehicle can be improved.
In the aspect of this section, in the above (Formula 1),
Since V1 = V2, by substituting this into (Equation 1),
W1 / W2 = 3.5 to 4.0: (Formula 3)
Can be obtained. That is, W1 and W2 may be set so as to satisfy the above (Formula 3). However, (Equation 3) is one measure in the aspect of this section similarly to (Equation 2), and the important thing in the aspect of this section is to satisfy (Equation 1).

  ADVANTAGE OF THE INVENTION According to this invention, the induction hardening method which can improve the precision of the cylindrical member in which an inner surface part is induction-hardened by inner surface moving hardening can be provided.

It is explanatory drawing of the coil and cooling jacket of an internal movement hardening apparatus, Comprising: It is a figure which shows an inboard cup with a dashed-two dotted line. It is a figure which shows the AA cross section of the inboard cup in FIG. 1 with a continuous line. It is a figure which expands and shows the right side part of the inboard cup in FIG. It is a figure which shows the measurement result of the groove width of the roller groove | channel obtained by the conventional induction hardening method. It is explanatory drawing of Example 1 of this embodiment, Comprising: The 1st quenching step from the mouth P0 to the heat input switching position P1 is induction-hardened with the 1st heat input Q1, and it is continuously heat input switching position. It is a measurement result of the groove width of the roller groove | channel in the inboard cup (tubular member) obtained by induction-hardening the 2nd hardening step from P1 to the back end P2 with the 2nd heat input Q2.

  An embodiment of the present invention will be described with reference to the accompanying drawings. Here, a method of induction hardening the inner surface portion 2 of the inboard cup 1 (cylindrical member) of the constant velocity joint by the inner surface moving quenching method will be described. That is, as shown in FIG. 1, an induction hardening device 11 is inserted into the inboard cup 1, and the induction hardening device 11 is axially above the inboard cup 1 (upward in FIG. 1). ), The inner surface 2 of the inboard cup 1 is sequentially heated and cooled from the mouth 3 toward the back 4 to form the hardened portion 5 on the inner surface 2 of the inboard cup 1. explain.

  The induction hardening apparatus 11 used in the induction hardening method of the present embodiment is a conventional inner surface transfer hardening apparatus, that is, the moving speed (inboard cup) of the coil 12, the cooling jacket 13, and the induction hardening apparatus 11. Since the structure is substantially the same as that of the induction hardening apparatus provided with a control device capable of controlling the relative movement speed (1) and the induction hardening apparatus 11) and the output, here, the induction hardening apparatus 11 is used. Detailed description relating to is omitted. Moreover, the inboard cup 1 as a cylindrical member is formed in a cup shape (see FIG. 1), and the inner surface portion 2 extends from the mouth 3 to the back 4 in the axial direction (vertical direction in FIG. 1). Thus, a plurality of (three in this embodiment) roller grooves 6 on which the ball rolls are equally arranged around the axis.

  In the induction hardening method of the present embodiment, as shown in FIG. 3, the mouth 3 on the inner surface 2 of the inboard cup 1 (tubular member) (position P 0 in FIG. When the length in the axial direction (distance between P0 and P2 in FIG. 3) from the mouth P0) to the back end (position P2 in FIG. 3, hereinafter referred to as the back end P2) of the quenched portion 5 is L The position where the depth from the mouth 3 is L / 3 is set as the heat input switching position (position P1 in FIG. 3). Further, the standard heat input, that is, the heat input (standard heat input) in the conventional induction hardening method in which the inner surface 2 of the inboard cup 1 is induction hardened with a constant heat input from the mouth P0 to the back end P2, is Q0. The first heat input in the process (first quenching step) from the mouth P0 to the heat input switching position P1 at the time of quenching is set to Q1 (Q1> Q0), and further the heat input switching position The second heat input amount in the process from P1 to the back end P2 (second quenching step) is set to Q2 (Q0> Q2).

  In the induction hardening method of the present embodiment, the first heat input amount Q1 in the first quenching step is set to 3.5 to 4.0 times the second heat input amount Q2 in the second quenching step (Q1). = Q2 * 3.5-4.0). Then, the inboard cup 1 is fixed with the mouth 3 facing downward, and the induction hardening device 11 is inserted into the inboard cup 1 (tubular member) to start the quenching (see FIG. 1). Position). Next, the quenching apparatus 11 is moved upward in the axial direction (relatively moved with respect to the inboard cup 1), and the inner surface portion 2 of the inboard cup 1 is sequentially heated and cooled from the mouth P0 to the back end P2. Thereby, the to-be-quenched part 5 is formed in the inner surface part 2 of the inboard cup 1.

  Here, in the induction hardening method of this embodiment, the process (first hardening step) from the mouth P0 to the heat input switching position P1 of the inner surface portion 2 of the inboard cup 1 is induction hardened with the first heat input Q1. Then, continuously, the process (second quenching step) from the heat input switching position P1 to the back end P2 is induction hardened with the second heat input Q2. As a result, the shrinkage amount of the hardened portion 5 in the inner surface portion 2 of the inboard cup 1 is adjusted so that the mouth 3 and the back 4 are substantially equal, and the mouth of the groove width D (see FIG. 2) of the roller groove 6 is adjusted. The opening on the 3 side is suppressed. As a result, the inboard cup 1 (tubular member) in which the accuracy of the groove width D of the roller groove 6 is ensured can be obtained.

  Here, in the conventional induction hardening method, the inner surface 2 is induction hardened at a constant moving speed (standard moving speed V0 = 10 m / s) and output (standard output W0 = 100 kW) from the mouth P0 to the back end P2. The inboard cup 1 (cylindrical member) to be used will be described as an example. In the induction hardening method according to the present invention, as described above, the first heat input amount Q1 in the first quenching step (section P0-P1) is equal to the second quenching step (section P1-P2). The heat input Q2 is set to 3.5 to 4.0 times, that is, the ratio between the first heat input Q1 and the second heat input Q2 is within a setting range (Q1: Q2 = 3.5 to 4.0: 1). Therefore, when calculating each heat input Q0, Q1, Q2, for convenience of explanation, the common term (default value C described in paragraph 0009) is not included in the calculation, and the unit of calculation result (kWs / m) is also omitted. . That is, each heat input Q0, Q1, Q2 is calculated as heat input Q = output W / movement speed V. That is, here, the heat input Q0 in the conventional induction hardening method is W0 / V0, that is, 10 (hereinafter referred to as heat input 10).

  FIG. 4 shows a measurement result of the groove width D (see FIG. 2) of the roller groove 6 in the inboard cup 1 obtained by a conventional induction hardening method as a comparison object. As shown in this figure, when induction hardening is performed with a constant heat input (standard heat input) 10 from the mouth P0 to the back end P2, the groove width D of the roller groove 6 at the mouth P0 is the groove at the back end P2. 40 μm larger than the width D (open). On the other hand, in the first embodiment, the first quenching step, that is, the process from the mouth P0 to the heat input switching position P1, is performed with the first moving speed V1 of 4 m / s and the first output W1 of 120 kW. Induction hardening under the input conditions. Continuously, the second quenching step, that is, the process from the heat input switching position P1 to the back end P2, is induction-hardened under the quenching condition of the second moving speed V2 of 11 m / s and the second output W2 of 90 kW. To do.

In Example 1, the first heat input amount Q1 in the first quenching step is 30, and the second heat input amount Q2 in the second quenching step is 8.2. , Output)
Q1>Q0> Q2 (hereinafter referred to as quenching condition 1)
And Q1 = Q2 × 3.5 to 4.0 (hereinafter referred to as quenching condition 2)
Meet.

  FIG. 5 shows that the process from the mouth P0 to the heat input switching position P1 (first quenching step) is induction-hardened under the quenching condition of the heat input 30 (first heat input), An inboard cup obtained by induction hardening of the process (second quenching step) from the heat input switching position P1 to the back end P2 under the quenching condition of the heat input 8.2 (second heat input) It is a measurement result of groove width D of roller groove 6 in 1 (tubular member). As shown in this figure, in the inboard cup 1 induction-hardened under the quenching conditions of Example 1 satisfying the quenching conditions 1 and 2, the groove width D of the roller groove 6 at the mouth P0 is 5 μm larger (open) than the groove width D at the end P2. That is, in Example 1, the opening of the mouth 3 having the groove width D in the roller groove 6 of the inner surface 2 of the inboard cup 1 can be reduced to 1/8 of the conventional induction hardening method (see FIG. 4). did it.

  In Example 1, the moving speed (V1, V2) and output (W1, W2) of the induction hardening apparatus 11 are compared with the quenching conditions (moving speed V0 and output W0) in the conventional induction hardening method. Although both are changed, the first quenching step and the second quenching step are held at a constant output (W1 = W2 = W0) on condition that the quenching conditions 1 and 2 described above are satisfied, The first quenching step can be induction hardened at a moving speed V1 (V0> V1) and the second quenching step can be induction hardened at a moving speed V2 (V2> V0). On the other hand, on condition that the above-described quenching conditions 1 and 2 are satisfied, the first quenching step and the second quenching step are maintained at a constant moving speed (V1 = V2 = V0), The quenching step can be induction hardened with output W1 (W1> W0) and the second quenching step can be induction hardened with output W2 (W0> W2).

This embodiment has the following effects.
According to the present embodiment, the axial distance from the mouth 3 when the length in the axial direction from the mouth P0 of the inboard cup 1 (tubular member) to the back end P2 of the to-be-quenched portion 5 is L is L. The position of / 3 is set as the heat input switching position P1. Then, the standard heat input amount, that is, from the mouth P0 when the heat input amount in the conventional induction hardening method of quenching the inner surface 2 of the inboard cup 1 with a constant heat input from the mouth P0 to the back end P2 is Q0. The first heat input in the process up to the heat input switching position P1 (first quenching step) is set to Q1 (Q1> Q0) and the process from the heat input switching position P1 to the back end P2 (second quenching step) ) Is set to Q2 (Q0> Q2), and the first heat input Q1 in the first quenching step is set to 3.5 to 4 of the second heat input Q2 in the second quenching step. Set to 0 times (Q1 = Q2 × 3.5 to 4.0). In the first quenching step, the inner surface portion 2 of the inboard cup 1 is sequentially heated and cooled with the first heat input amount Q1, and continuously, in the second quenching step, the inner surface portion 2 of the inboard cup 1 is used. Are sequentially heated and cooled with the second heat input amount Q2 to form the hardened portion 5 on the inner surface portion 2.
Thus, conventionally, the groove width D of the roller groove 6 of the inboard cup 1 (cylindrical member) has a tendency to open in a tapered shape from the back 4 toward the mouth 3. By induction hardening under the quenching conditions, the shrinkage amount of the portion to be quenched 5 is adjusted to be approximately equal at the mouth 3 and the back 4. Therefore, the groove width D of the roller groove 6 can be made substantially equal at the mouth 3 and the back 4, and the dimensional tolerance of the groove width D of the roller groove 6 can be ensured. In the constant velocity joint to which the inboard cup 1 obtained in this way is assembled, it becomes possible to reduce the backlash between the roller and the roller groove 6 and to reduce noise and vibration while the vehicle is running. Thus, the comfort of the vehicle can be improved.

DESCRIPTION OF SYMBOLS 1 Inboard cup (cylindrical member), 2 inner surface part, 3 mouth base, 4 back, 11 induction hardening apparatus (inner surface moving hardening apparatus), Q0 standard heat input, Q1 1st heat input, Q2 2nd heat input, V0 standard movement speed, V1 first movement speed, V2 second movement speed, W0 standard output, W1 first output, W2 second output

Claims (3)

A method of induction hardening a roller groove extending in an axial direction provided on an inner surface portion of an inboard cup of a constant velocity joint by an inner surface moving quenching method,
Set the heat input to the inboard cup when induction hardening at a constant heat input from the mouth of the inboard cup deep standard amount of heat input, the first input of increasing relative to the standard heat input A first quenching step of quenching the mouth side of the inboard cup with a quantity of heat;
See contains a second quenching step of quenching the back side of the inboard Cup second heat input was reduced to the standard amount of heat input,
The first heat input is 3.5 to 4.0 times the second heat input,
Induction hardening is performed from the first quenching step to the second quenching step when quenching proceeds from the mouth of the inboard cup to 1/3 of the axial length of the roller groove. How to enter. Set the moving speed at the time of induction hardening at a constant moving speed from the mouth of the inboard cup to the back of the induction hardening apparatus and the inboard cup as the standard moving speed,
In the first quenching step, the mouth side of the inboard cup is quenched at a first moving speed reduced with respect to the standard moving speed,
2. The induction hardening method according to claim 1 , wherein in the second quenching step, the back side of the inboard cup is quenched at a second movement speed increased with respect to the standard movement speed. Set the output when induction hardening with a constant output from the mouth of the inboard cup to the back of the induction hardening device to the standard output,
In the first quenching step, the mouth side of the inboard cup is quenched with a first output increased with respect to the standard output,
2. The induction hardening method according to claim 1 , wherein in the second quenching step, the back side of the inboard cup is quenched with a second output reduced with respect to the standard output.

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