JP2000273543A - High frequency induction hardening apparatus and hardening control method used for the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the pitch error after hardening even in the case of being a carbon steel-made or alloy steel-made ball thread, or cut thread or rolled thread, as a work. SOLUTION: A high frequency induction hardening apparatus 100 is provided with a hardening mechanism 110, a temp. measuring instrument 180 fitted to this mechanism, a transporting mechanism 130 for transporting the hardening mechanism 110 along the work W and a turning and elongation detecting mechanism 150 for turning the work W and also, detecting the elongation of the work W, etc., are provided. In a hardening control method, by which for reducing the pitch error after high frequency induction hardening of the ball thread as the transported and hardened work W, the extension of the whole length of the work W during transporting and hardening, is measured and the heating quantity to the portion in the work W hardened thereafter, is corrected by utilizing the data of the measured result of this elongation, the temp. before hardening the work W and the remaining temp. at the portion just after hardening the work W, are measured. The heating quantity of the work W is further corrected so as to reduce the pitch error by utilizing the data of measured temp. difference, and to the portion in the work W hardened thereafter, the transportation and the hardening based on this correction, are progressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction hardening apparatus using a ball screw as a work and a hardening control method used for the apparatus.

[0002]

2. Description of the Related Art A ball screw is a JI that defines its accuracy.
According to SB 1191, 1192, C0, C1, C
Precision ball screw consisting of 4 grades of 3, C5 and C7, C
And 10 general grade ball screws.

In the grades C0, C1, C3, and C5, the read errors include accumulated actual read error, accumulated representative read error,
Three items of fluctuation are specified. Regarding the variation, for example, the maximum width of the accumulated actual lead corresponding to 300 mm arbitrarily taken between the effective lengths of the screw portion of the screw shaft is defined, and each allowable value of C0, C1, C3, and C5 is specified. Are 3.5 μm, 5 μm, 8 μm and 18 μm.

In the grades C7 and C10, only the lead error with respect to the total lead between the 300 mm screw grooves arbitrarily taken between the effective lengths of the screw portion of the screw shaft is specified. C
7, the allowable value of the cumulative read error of C10 is 50μ at C7.
m and C10 are 210 μm.

[0005] On the other hand, ball screws are roughly classified according to the manufacturing method, into general ball screw equivalent products in which the thread portion is rolled or cut, and precision ball screw equivalent products in which the thread portion is subjected to precision screw grinding (cutting / polishing). Divided. Furthermore,
When classified according to the processing method, they are classified into cutting screws formed by cutting and rolled screws formed by rolling. Generally, ball screws for general use are manufactured by rolling when the lot is relatively large, and are manufactured by cutting when the lot is small in lots of various kinds.

[0006] In both the precision ball screw and the general ball screw, the screw portion is hardened during the manufacturing stage.

As shown in FIG. 3, a conventional induction hardening apparatus 900 for moving and hardening a ball screw as a workpiece W includes a hardening mechanism 910 and a moving mechanism for moving the hardening mechanism 910 along the workpiece W. A mechanism 930, a rotation / elongation detection mechanism 950 that rotates the work W and detects elongation of the work W, and a control unit (not shown) that controls these mechanisms are provided.

The quenching mechanism 910 includes a so-called saddle-type high-frequency heating coil 911 and the high-frequency heating coil 911.
And a cooling jacket 914 for injecting a cooling liquid for quenching. The quenching mechanism 910 is movably attached to a later-described ball screw 931 of the moving mechanism 930.

The moving mechanism 930 includes a ball screw 931 installed in parallel with the workpiece W and a motor 9 for rotating the ball screw 931.
32.

The rotation / elongation detecting mechanism 950 includes a chuck 951 for holding one end of the work W for rotating the work W, and a motor 95 for rotating the chuck 951.
2 and a length measuring unit 953 that forms a pair with the chuck 951 and presses the center of the other end of the work W and detects elongation of the work W.

[0011] In the conventional induction hardening apparatus 900 configured as described above, the workpiece W is hardened as follows. First, as a preliminary preparation, one work similar to the production work W to be hardened is prepared.
Quenching is performed under standard conditions that satisfy the quenching specifications to create data that becomes a model. The standard conditions here are, for example, 150 kW of electric power applied to the high-frequency heating coil body 911, and a feed speed v for moving the quenching mechanism 910 of 10 mm / sec (constant). These conditions are set in the control unit, and the work is hardened. It should be noted that stop heating is usually performed before quenching (moving quenching), whether this model work or a production work W to be described later (see FIG. 5).

After the work is hardened, the length measuring unit 953
Then, the length of the work is measured by measuring the length of the work after the work is completely cooled. The elongation is calculated from the measured value. For example, if the entire length of the work is 1 m and the work is elongated by 1 mm after quenching, the elongation rate of the work is 1 per mill. This elongation becomes the reference elongation and is set in the control unit.

When the work W for production is machined,
It is made in advance by correcting the overall length to be shorter by 1 mm.

Next, quenching is performed on the pre-corrected production work W. At this time, when the workpiece W is a cutting screw, the workpiece W is shown in FIGS.
As shown in the figure, the quenching depth x is a predetermined depth (for example, x
= 3.2 mm), the elongation is zero, but tends to increase as the quenching depth x becomes deeper than the predetermined depth, and conversely, shrink as the quenching depth x becomes shallower than the predetermined depth. .

Using this tendency, the reference elongation percentage, and the measured value of elongation by the length measuring unit 953, the control unit performs the following feedback control during the moving quenching period to perform the work W Quenching is automatically controlled.

The basic conditions are the same as the above-mentioned standard conditions. The power applied to the high-frequency heating coil 911 is 150 kW, and the feed speed v for moving the quenching mechanism 910 is 10 mm / sec. After the quenching of the work W is started under these basic conditions, the control unit calculates the elongation rate of the work W by measuring the elongation of the work W by the length measuring unit 953 at a fixed span (time interval).

The control section compares the elongation rate with the reference elongation rate (1 per mil). If the elongation rate is not reached, the feed rate v is decreased, and if the rate is exceeded, the feed rate v is increased. Feedback control is performed so as to be as close as possible to the reference elongation rate. If the feed speed v is reduced, the work W
(Heating amount per unit area) is increased, thereby increasing the quenching depth, and the work W showing the tendency of FIG. 4A is elongated (in some cases, the shrinkage is reduced), and the elongation rate is increased. Is large. On the other hand, when the feed speed v is increased, the amount of heating of the work W is reduced, and thereby the quenching depth is reduced, and the amount of extension of the work W having the tendency shown in FIG. , The elongation is small. That is, since the elongation can be adjusted by adjusting the feed speed v,
The feedback control is performed using this fact.

The feedback control is performed for the following reason. The work W has substantially the same material in the same lot, but still has some variation in the material. Further, even in the same lot, for example, when the sharpness of a cutting tool used for cutting is deteriorated, or when the margin for one cut is changed, the residual stress after the processing of the workpiece W is slightly different. If the feedback control is not performed, the feed speed v is kept constant at 10 mm / sec, and the influence of the variation and the difference of the residual stress appears as it is. Because of the pitch).

When the next lot, which should be of the same material, is quenched, the variation in the material between lots is often larger than the variation in the lot. This is because the variation in dimensions after the quenching of the work W is further increased. It should be noted that when the lot is changed, it is possible to re-create the template again, and this may be done in some cases. In this case, while it is necessary to spend extra cost and time, it is not possible to avoid the influence of the variation in the material within the lot.

[0020]

When the work W is a rolled screw, as shown in FIG. 4B, the work W always shrinks when quenched, and further increases as the quenching depth x increases. They tend to shrink. For this reason, if the quenching is performed with the induction hardening device 900 prepared in advance and the feedback control is performed as described above, there are the following problems.

If the elongation is not reached, the quenching depth is increased to reduce the feed speed v, and the elongation of the work W further proceeds in the negative direction. Then, since the feedback control is applied so that the feed speed v is further reduced, the heating of the work W becomes excessive, and the work W is eventually melted. In other words, the feedback control can function effectively when the workpiece W is a cutting screw and is made of carbon steel as described later.
It cannot be applied to the case of rolled screws (however, this is the case where the above-mentioned preparations have been made). For this reason, when the work W is a rolled screw, the automatic control to suppress the variation in the dimension after quenching is not performed, and the variation in the dimension after quenching is large.

Further, even if the work W is a cutting screw, if it is made of alloy steel, the state of elongation at the time of quenching is as shown in FIG. 5, and there is the following problem. . The elongation during quenching during the moving quenching period is (Δd / d) × 1000
It is. Here, d is a measurement interval dimension, and Δd is an elongation dimension detected by the length measuring unit 953 in the measurement interval dimension d. The elongation during quenching is measured to control the feed rate v, but the component of Δd is a problem.

That is, Δd = “component of elongation of work W due to martensite expansion” + “component of elongation of work W due to residual temperature”, and elongation of work W due to residual temperature is greater than that of work W It is larger than the component of elongation due to martensite expansion. For this reason, when the remaining temperature of the work W can be reduced to substantially zero, that is, until the temperature before the quenching of the work W becomes almost equal to the temperature after the quenching, the cooling jacket 9 is cooled.
If it is made of carbon steel that can be cooled by spraying the cooling liquid from 14, there is no problem.

However, when the work W is made of an alloy steel, cracking occurs unless the remaining temperature is about 80 ° C. Therefore, when the work W is made of alloy steel, the component of the elongation due to the residual temperature of the work W becomes larger than the component of the elongation of the work W due to the martensite expansion, and the error becomes extremely large. The feedback control was impossible. Therefore, when the work W is made of an alloy steel, the feedback control is not possible even if the work W is a cutting screw. Therefore, the automatic control for suppressing the variation in the size after quenching is not performed. Variations had increased.

As described above, the conventional automatic control works effectively only when the work W is a cutting screw and is made of carbon steel. However, the work W is a cutting screw and is made of alloy steel or rolled. If it is a screw (in this case made of carbon steel or alloy steel), the conventional automatic control is not effective. Therefore, only when the work W is a cutting screw and is made of carbon steel, the variation in the dimension after quenching can be reduced, but in other cases, the variation in the dimension after quenching is large. However, even when the work W is a cutting screw and made of carbon steel, the induction hardening device 900 does not have a function of detecting the remaining temperature of the work W. The effect of the "elongation component due to quenching" remains, and the accuracy of the dimensional adjustment after quenching has not yet been sufficiently increased, and variations have occurred.

When the work W is a cutting screw and is made of alloy steel, there are two possibilities: a case where the ball screw as the work W is a precision ball screw and a case where the ball screw is a general ball screw. In the case of a precision ball screw, it is necessary to polish in the subsequent process after quenching to correct the pitch error, but since the variation in dimensions after quenching is far from the level required for precision ball screws, polishing It takes a long time, and the grinding wheel is severely worn, which is an obstacle to reducing the manufacturing cost. On the other hand, in the case of a general-purpose ball screw, the cutting process itself can provide an accuracy higher than that required for the general-purpose ball screw. Normally, there is no problem within the required level.

When the work W is a rolled screw, the work W is a general ball screw. Therefore,
Since precision is not required, there is almost no polishing in a post-process after quenching. However, from the market,
There is a strong demand for a rolled screw that can be manufactured at a low cost and that can provide the same precision (pitch accuracy) as a precision ball screw. In order to meet this demand, feedback control during quenching is indispensable, but has not been performed for the reasons described above.

The main object of the present invention is to provide an induction hardening device which can reduce pitch errors after quenching, whether the ball screw as a work is made of carbon steel or alloy steel, or a cutting screw or a rolled screw. And a quenching control method used for the same.

[0029]

In order to solve the above-mentioned problems, an induction hardening apparatus according to a first aspect of the present invention is a length measuring apparatus for measuring the elongation of a ball screw as a workpiece during moving hardening. In the induction hardening device having a control unit that corrects a heating amount for the portion of the work to be hardened by using the data of the elongation measured thereby, the temperature before the hardening of the work and Equipped with a temperature measuring device for measuring the residual temperature of the quenched part of the work,
Using the data of the temperature difference measured thereby, the control unit further corrects the amount of heating of the work so as to reduce a pitch error, and the part of the work to be quenched from now on is corrected. Characterized in that the quenching is carried out by moving.

An induction hardening apparatus according to a second aspect of the present invention is an induction hardening apparatus for moving and quenching a ball screw as a workpiece, wherein the temperature of a portion before quenching the workpiece and the temperature immediately after quenching the workpiece. Using a temperature measuring device that measures the temperature of the part, and using the data of the temperature measured by this, the temperature of the part before the quenching of the work and the temperature of the part immediately after the quenching of the work are substantially the same. And a control unit for performing the control described above.

According to a third aspect of the present invention, in the induction hardening apparatus according to the second aspect of the present invention, the target temperature of the portion immediately after the quenching of the work is temporarily set to a predetermined higher temperature because of the material thereof. After the quenching is performed, it is necessary to allow the work to adapt to the environmental temperature, and the part before quenching of the work is replaced by the part immediately after quenching of the work before quenching is started. It is characterized by having a mechanism for heating until the temperature becomes substantially the same as the cooling target temperature.

An induction hardening apparatus according to a fourth aspect of the present invention is an induction hardening apparatus for moving and hardening a ball screw as a work, wherein a hardening mechanism for performing the induction hardening on the work, and a hardening mechanism for the hardening mechanism. A first temperature measuring device that is provided on the downstream side and measures the temperature of the work before quenching, and measures a length between predetermined pitches of a portion where the temperature is measured by the first temperature measuring device. A first length measuring device, a second temperature measuring device provided upstream of the quenching mechanism for measuring the temperature of the workpiece after quenching, and a temperature measured by the second temperature measuring device. A second length measuring device that measures the length of the portion between predetermined pitches, a moving mechanism that moves the quenching mechanism along the work, and a control unit that controls these. And the first length measuring device and the second Between the length unit is set to a predetermined distance s, the the feeding speed of the quenching mechanism using the moving mechanism is to v, the first and the first temperature measuring device
Temperature and length measurement data measured by the length measuring device, and the temperature and length measured by the second temperature measuring device and the second length measuring device after s / v of the measurement. The control unit corrects the amount of heating of the portion of the work to be quenched from now on using the data of the measurement so as to reduce a pitch error.

A quenching control method according to claim 5 of the present invention is characterized in that:
In the quenching control method of measuring the elongation of the entire length of the ball screw as a workpiece during moving quenching and using the data of the measurement result of the elongation to correct the heating amount for the portion of the workpiece to be quenched, Measure the temperature of the work before quenching and the remaining temperature of the quenched part of the work,
Using the data of the measured temperature difference, the heating amount of the work is further corrected to reduce the pitch error,
It is characterized in that moving quenching is advanced to a portion of the work to be quenched.

A quenching control method according to claim 6 of the present invention is characterized in that:
In a quenching control method for reducing a pitch error after induction hardening of a ball screw as a workpiece to be moved and quenched, the temperature of a part before quenching of the workpiece and a temperature of a part immediately after quenching of the workpiece are determined. Are controlled to be substantially the same.

A quenching control method according to claim 7 of the present invention is characterized in that:
7. The work according to claim 6, wherein, due to its material, the cooling target temperature of a portion immediately after the quenching of the work needs to be once maintained at a predetermined higher temperature, and then the work needs to be adapted to the environmental temperature. The portion of the workpiece before quenching is heated until the quenching is started until the temperature of the portion immediately after the quenching of the workpiece becomes substantially equal to the target cooling temperature.

A quenching control method according to claim 8 of the present invention is characterized in that:
The length and temperature of the part before quenching of the ball screw as a work, and the length and residual temperature of the part after quenching are measured, and the measurement result is used to quench the part of the work to be quenched. Is corrected so as to reduce the pitch error.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an induction hardening apparatus according to a first embodiment of the present invention for realizing a quenching control method according to a fifth aspect of the present invention will be described with reference to FIG. The induction hardening device according to the first embodiment of the present invention is an embodiment of the induction hardening device according to claim 1 of the present invention.
FIG. 1 is a schematic explanatory view showing an induction hardening apparatus according to a first embodiment of the present invention.

The induction hardening apparatus 100 according to the first embodiment of the present invention is an apparatus for moving and hardening a ball screw as a work W. The induction hardening device 100 includes a quenching mechanism 1
10, a temperature measuring device 180 attached to the quenching mechanism 110, a moving mechanism 130 for moving the quenching mechanism 110 along the work W, and a rotation mechanism for rotating the work W and detecting the extension of the work W. Motion / elongation detection mechanism 150
And a control unit (not shown) for controlling these.

The quenching mechanism 110 includes a so-called saddle-type high-frequency heating coil 111 and the high-frequency heating coil 111.
And a cooling jacket 114 for injecting a quenching coolant. The quenching mechanism 110 is movably attached to a later-described ball screw 131 of the moving mechanism 130.

The moving mechanism 130 includes a ball screw 131 installed in parallel with the workpiece W, and the motor 1 for rotating the ball screw 131.
32.

The rotation / elongation detecting mechanism 150 includes a chuck 151 for holding one end of the work W for rotating the work W, and a motor 15 for rotating the chuck 151.
2 and a length measuring unit 153 as a length measuring device for pairing with the chuck 151 to press the center of the other end of the work W and detect the elongation of the work W.

The temperature measuring device 180 can remotely measure the temperature, and is, for example, a radiation thermometer. The temperature measuring device 180 is physically attached to the current transformer 112. The direction aimed by the temperature measuring device 180 for measurement is the part of the work W held by the rotation / elongation detection mechanism 150,
Slightly downstream part.

The induction hardening device 10 thus configured
The value 0 indicates that the pitch error after quenching is reduced by feedback control by the control unit during the moving quenching period as follows.

When the work W is a cutting screw and made of alloy steel. First, as a preliminary preparation, one work similar to the production work W to be quenched is prepared as before, and quenching is performed on the work under standard conditions satisfying the quenching specification.
Create data to be a template. The standard conditions here are, for example, 150 kW of electric power applied to the high-frequency heating coil body 111, a feed speed v for moving the quenching mechanism 110 of 10 mm / sec (constant during the moving quenching period), and Is set.

After quenching the work, the length measuring unit 153
Then, the length of the work is measured by measuring the length of the work after the work is completely cooled. The elongation is calculated from the measured value. For example, assuming that the entire length of the work is 1 m and the work is elongated by 1 mm after quenching, the elongation percentage of the work is 1 per mil. This elongation becomes the reference elongation and is set in the control unit.

The actual work W is previously 1 mm in total length.
Make corrections when machining shorter. Next, the pre-corrected production work W is subjected to quenching while measuring the remaining temperature and the like with the temperature measuring device 180 and measuring the elongation with the length measuring unit 153. The timing of measuring the residual temperature may be the same as the timing of measuring the elongation in the length measuring unit 153. However, before the start of quenching, each state is measured.

At the time of this quenching, the work W exhibits the tendency shown in FIG. 4A for expansion and contraction, and this tendency, the measured value of elongation by the length measuring unit 153, and the standard elongation rate Using the measured value of the temperature measuring device 180 and the measured value, the control unit automatically controls the quenching of the work W by performing the following feedback control.

The basic conditions are the same as the standard conditions, the power applied to the high-frequency heating coil 111 is 150 kW, and the feed speed v for moving the quenching mechanism 110 is 10 mm / sec.
(Constant). After the quenching of the work W is started under these basic conditions, the control unit calculates the elongation rate of the work W by measuring the elongation of the work W by the length measuring unit 153 at a fixed span.

The elongation rate here is different from the conventional one and corrected as follows. The measurement interval is d, the elongation measured by the length measuring unit 153 is Δd, the temperature of the work W before quenching is T1 ° C., the temperature of the portion immediately after the quenching of the work W (remaining temperature) is T2 ° C. The expansion coefficient is 1.1 × 10 ⁻⁵ . "Elongation only by quenching" = Δd-1.1 × 10 ⁻⁵ × d
Since (T2−T1), “elongation rate only by quenching” = [Δd−1.1 × 10 ⁻⁵ ×
d (T2−T1)] × 1000 / d = [Δd / d−1.1 × 10 ⁻⁵ (T2−T1)] × 10
00. Therefore, unlike the conventional case, 1.1 × 10 ⁻⁵ (T2−
T1) × 1000 correction, that is, 1.1 × 10
^-2 (T2-T1) correction is added.

The control unit compares the elongation rate due to the quenching only with the reference elongation rate (1 per mil). If the elongation rate is not reached, the amount of power applied to the high-frequency heating coil body 111 is increased and exceeded. In this case, the amount of power applied to the high-frequency heating coil body 111 is reduced to adjust the amount of heating applied to the workpiece W, and feedback control is performed so as to be as close as possible to the reference elongation rate. When the heating amount is adjusted, the quenching depth changes, and the quenching depth changes to show the tendency shown in FIG. 4A. Therefore, the elongation amount is changed and the elongation rate is adjusted. That is.

As described above, even if the work W is a cutting screw and is made of an alloy steel, by performing the above correction, it becomes possible to perform automatic control for reducing the pitch error after quenching.

When the work W is a cutting screw and made of carbon steel.

Basically, this is the same as the above case where the work W is a cutting screw and is made of alloy steel. If the work W is made of carbon steel, the remaining temperature of the part immediately after the quenching of the work W is
The only difference is that the temperature can be reduced to the temperature (environmental temperature) of the work W before quenching. That is, the relationship between T2 and T1 is represented by T
2 can be set to T1, which will be described later.

When the work W is a cutting screw and is made of carbon steel, T2 and T1 have different values if the above-mentioned correction by the quenching control method according to the first embodiment of the present invention is added. However, automatic control can be performed to reduce the pitch error after quenching as compared with the related art. In addition, as described above, T2
When not set to T1, the cooling control by the cooling jacket 114 does not need to be strictly controlled as described later, and therefore can be simplified.

When the work W is a rolled screw and made of alloy steel. In this case as well, the same procedure as described above is used. However, if the work W is a rolled screw, the work is contracted as the quenching depth is increased. A newly prepared template work similar to the production work W to be quenched is subjected to quenching under the standard conditions, and shrinks when the work is completely cooled and measured. The elongation percentage (negative elongation percentage) is calculated from the measured values. For example, assuming that the length of the work is 1 m and it is elongated by -1 mm after quenching (that is, contracted by 1 mm), the elongation of the work is -1 per mil. This elongation becomes the reference elongation and is set in the control unit.

When the actual work W is machined,
In this case, the overall length is corrected to be shorter by -1 mm (that is, 1 mm longer). In addition, "elongation rate only by quenching" =
[Δd / d-1.1 × 10 ⁻⁵ (T2−T1)] × 100
0 can be used as it is because Δd only takes a negative value. The control unit compares the elongation rate (negative elongation rate) due to only this quenching with the reference elongation rate (-1 per mil).
11, the amount of power applied to the high-frequency heating coil body 111 is reduced, and the amount of power applied to the workpiece W is adjusted. Control. When the heating amount is adjusted, the quenching depth changes, and the quenching depth changes to show the tendency shown in FIG. 4B. Therefore, the elongation amount (minus elongation amount) is changed. The growth rate (negative growth rate) is adjusted.

As described above, even if the work W is a rolled screw and is made of an alloy steel, by performing the above correction, automatic control for reducing the pitch error after quenching becomes possible.

The case where the work W is a rolled screw and made of carbon steel. The above-mentioned contents are simply applied to the above-described contents, and the description thereof is omitted. However, even if the work W is a rolled screw and made of carbon steel, the work W can be performed by performing the correction described above. Automatic control for reducing the pitch error after the entry is made possible.

In the quenching control method according to the first embodiment of the present invention, the adjustment of the amount of heating (that is, the adjustment of the quenching depth) is performed by changing the feed speed v. Although the adjustment was performed by adjusting the amount of power applied to the high-frequency heating coil body 111 while keeping it constant, for example, the feed rate v
May be adjusted.

Next, the induction hardening apparatus according to the second to fourth embodiments of the present invention (the second embodiment of the present invention) for realizing the quenching control methods according to the sixth and seventh aspects of the present invention. And an induction hardening device according to an embodiment of claim 3). The induction hardening apparatus according to the second to fourth embodiments of the present invention is a modification of the induction hardening apparatus 100 according to the first embodiment of the present invention. This will be described with reference to the induction hardening device 100 of FIG.
The common features of the induction hardening apparatuses according to the second to fourth embodiments of the present invention are as follows.

In the quenching control method according to the sixth aspect of the present invention, the influence of the remaining temperature of the work W is determined by T2 = T1 (or T2 ≒ T1), that is, T2-T1 = 0 (or T2-T1 ≒).
By eliminating (or almost eliminating) 0), the pitch error after quenching is reduced.

If the work W is made of carbon steel, the temperature (remaining temperature) T2 of the portion immediately after quenching of the work W, whether it is a cutting screw or a rolled screw, is determined by The temperature of the work W is reduced to a temperature T1 (usually the ambient temperature) by spraying the cooling liquid from the cooling jacket 114 at a stretch. Therefore, when the work W is made of carbon steel, the control unit determines the injection amount of the cooling liquid of the cooling jacket 114 by using the temperature measuring device 1.
Control is performed so that T1 = T2 based on the 80 measured values T1 and T2.

On the other hand, if the work W is made of alloy steel, the temperature (remaining temperature) T2 of the portion immediately after quenching of the work W, whether it is a cutting screw or a rolled screw, is determined by When the temperature of the work W is reduced to a temperature T1 (usually the ambient temperature) by spraying the cooling liquid from the cooling jacket 114 at a stretch, the work W
May crack. Therefore, in order to set T1 = T2, the temperature T1 of the work W before quenching is set in the following (1) to (1).
As described in (3), the temperature is raised in advance to T1 ′ (= T2 + α) so that T1 ″ (= T2) at the start of the quenching of the work W. Here, T1 is the environmental temperature, and T1 ′ is T1 ′. The pre-heating temperature, T1 ″, is a cooling target temperature (here, for example, 80 ° C.) when the work W is made of an alloy steel.

(1) The temperature T1 of the work W before quenching is set to a preheating temperature T1 '(= T2 + α = 80 ° C. +
The induction hardening apparatus according to the second embodiment of the present invention, which has a configuration for raising to α), is as follows.
The induction hardening apparatus according to the second embodiment of the present invention is obtained by adding a separate furnace (not shown) to the induction hardening apparatus 100. Before the work W is mounted on the induction hardening apparatus 100, the furnace T1 '(= T2
+ Α = 80 ° C. + α).

The worker puts the work W into the furnace, preheats it, takes it out, and sets it in the induction hardening apparatus 100. The value of α is in anticipation that the temperature of the work W will decrease after the setting and before the start of the moving quenching. Therefore, the start of the moving quenching indicates that the temperature of the work W has almost reached the target cooling temperature T1 ″ = 80 ° C.
It will start after it can be confirmed by 0.

(2) The temperature T1 of the work W before quenching is previously set to the preheating temperature T1 '(= T2 + α = 80 ° C. +
An induction hardening apparatus according to a third embodiment of the present invention having another configuration for raising the temperature to α) is as follows. In the induction hardening apparatus according to the third embodiment of the present invention, the control program of the control unit of the induction hardening apparatus 100 is slightly changed as follows, so that the quenching mechanism 110 directly contributes to preheating. I have to. That is, the quenching mechanism 110
Thus, the workpiece W is pre-heated before quenching.
Of course, at this time, the cooling jacket 114 is not operated.

Therefore, for example, before the stop heating period, the quenching mechanism 110 is moved along the work W from the base end to the tip of the work W at a constant speed by the moving mechanism 130, and at that time, the quenching A lower predetermined power is applied to the high-frequency heating coil body 111 to set the workpiece W to the pre-heating temperature T1 '. Return the quenching mechanism 110 to the base end side,
A predetermined quenching operation after the stop heating is performed. The moving quenching is started at a target cooling temperature T1 ″ near the quenching start position of the workpiece W.
= 80 ° C.

In order to set the preheating temperature T1 ', a predetermined electric power lower than that at the time of quenching is applied to the high-frequency heating coil body 11.
1, the same power as in the quenching is supplied to the high-frequency heating coil body 111 and the quenching mechanism 110 is provided.
May be increased. The quenching mechanism 110
May be stopped from returning to the base end side, and a predetermined hardening operation after the stop heating may be performed from the front end side of the work W to the base end side.

(3) The temperature T1 of the work W before quenching is set in advance by a preheating temperature T1 '(= T2 + α = 80 ° C. +
An induction hardening apparatus according to a fourth embodiment of the present invention, which has still another configuration for raising to α), is as follows. It is a part of the quenching mechanism 110 of the induction hardening apparatus 100 and is located in front of the induction heating coil body 111 (the workpiece W).
A high-frequency heating coil for pre-heating is newly provided in the direction of the front end of the coil, and a current transformer for this high-frequency heating coil is also newly provided. Thus, when quenching is performed using the high-frequency heating coil 111, the high-frequency heating coil for preheating also operates. In this case, + α
May be close to zero.

As described above, the induction hardening apparatus according to the second to fourth embodiments of the present invention can be applied to the case where the work W is made of carbon steel or alloy steel, and whether the work W is made of a cutting screw or a rolled screw.
The pitch error after quenching can be reduced.

In the case of the induction hardening apparatuses according to the second to fourth embodiments of the present invention, the preheating temperature T1 'is previously determined.
(= T2 + α = 80 ° C. + α). Alternatively, the preheating temperature may be T2 (= 80 ° C.) and a heat source may be added so that the temperature does not decrease. The heat source is a heater, a hot air device, or the like, and is preferably provided along a position where the work W is set. Thereby, a temperature change which causes an error can be prevented, so that a pitch error after quenching can be reduced.

Further, in the case of the induction hardening apparatuses according to the second to fourth embodiments of the present invention, since the amount of electric power or the feeding speed to be applied to the high-frequency heating coil during the hardening is controlled,
Although the amount of heating given to the work W changes, the remaining temperature changes if the amount of cooling by the injection of the cooling liquid from the cooling jacket is also constant. Therefore, the amount of cooling changes with the change in the amount of power or the feed rate. , More or less.

In the case of the induction hardening apparatuses according to the second to fourth embodiments of the present invention, T2−T1 = 0 is set in order to eliminate the influence of the residual temperature. Considering the fact that there are some, it is of course possible to add the correction described in the first embodiment of the present invention to the control in order to reduce the pitch error after quenching.

The quenching control methods according to claims 6 and 7 of the present invention are based on the conventional induction hardening apparatus 900.
Is also applicable. However, the conventional induction hardening device 9
00 does not have an equivalent to the temperature measuring device 180, so that accurate temperature control cannot be performed.
Cannot achieve the accuracy as high as that of the induction hardening apparatus according to the embodiment.

Next, an induction hardening apparatus according to a fifth embodiment of the present invention for realizing the quenching control method according to claim 8 of the present invention will be described with reference to FIG. The induction hardening device according to the fifth embodiment of the present invention is an embodiment of the induction hardening device according to claim 4 of the present invention. FIG. 2 is a schematic explanatory view showing an induction hardening device according to a fifth embodiment of the present invention.

The induction hardening apparatus 200 according to the fifth embodiment of the present invention is also an apparatus for moving and hardening a ball screw as a workpiece W. The induction quenching device 200 includes a quenching mechanism 1
10, a first temperature measurement device 281 and a second temperature measurement device 282 attached to the quenching mechanism, and a quenching mechanism so as to be placed on the workpiece W before and after the quenching mechanism. A moving mechanism (not shown) similar to the first length measuring device 291 and the second length measuring device 292 provided and the moving mechanism 130 for moving the quenching mechanism along the workpiece W.
A rotation / elongation detection mechanism (not shown) similar to the rotation / elongation detection mechanism 150 for rotating the work W and detecting the elongation of the work W, and a control unit (not shown) for controlling these mechanisms. Have.

The quenching mechanism includes a so-called saddle-type high-frequency heating coil 211, a current transformer (not shown) and a high-frequency oscillator (not shown), which are power circuits of the high-frequency heating coil 211, and a quenching device. A cooling jacket 214 for injecting a cooling liquid. The quenching mechanism configured as described above is movably attached to a ball screw similar to the ball screw 131 of the moving mechanism.

The first temperature measuring device 281 and the second temperature measuring device 282 are the same as the temperature measuring device 180, and are physically attached to the current transformer. The direction aimed by the first temperature measuring device 281 for measurement is a portion of the work W held by the rotation / elongation detecting mechanism, and is slightly downstream of the high-frequency heating coil body 211 (that is, before quenching). Part). The direction aimed by the second temperature measuring device 282 for measurement is a portion of the work W held by the rotation / elongation detection mechanism, and a portion slightly upstream of the cooling jacket 214 (that is, after quenching). Part).

The first length measuring device 291 and the second length measuring device 2
Reference numeral 92 denotes a pair of spheres 295 that respectively engage with the groove WM of the workpiece W, shafts 296 provided on the pair of spheres 295, and a displacement sensor 297 provided between the pair of shafts 296. And The pair of spheres 295 are provided in accordance with the pitch of the work W. The displacement sensor unit 297 is a linear sensor such as a magnescale.

The first length measuring device 291 and the second length measuring device 2
92 is provided at a predetermined distance. The position where the first length measuring device 291 is provided is a portion that the first temperature measuring device 281 aims to measure (that is, a portion before quenching). Further, the position where the second length measuring device 292 is provided is a portion aimed at by the second temperature measuring device 282 for measurement (that is, a portion after quenching).

The induction hardening apparatus 200 is configured as described above for the following reasons. In the induction hardening devices according to the first to fourth embodiments of the present invention, the length measuring unit 15
Since the total length of the work W is measured and the elongation percentage is calculated and fed back in 3, an error occurs if the temperature (particularly the remaining temperature of the work W) is not constant over the entire length of the work W.
In order to minimize this error, in the induction hardening apparatus 200 according to the fifth embodiment of the present invention, the length to be measured is set one place before and after the high frequency heating coil body 211 (that is, the part before quenching). And the part after quenching).

Based on the data measured by the induction hardening apparatus 200, the elongation rate by quenching alone is calculated as follows. The work W in the part before quenching
Is T1 ° C., the temperature (residual temperature) of the part after quenching of the workpiece W is T2 ° C., the measured length of the part before quenching is d1, and the measured length of the part after quenching is d2. I do.

"Elongation rate only by quenching" = [(d2-d
1) -1.1 × 10 ⁻⁵ × d1 (T2-T1)] × 100
0 / d1 = [d2 / d1-1−1.1 × 10 ⁻⁵ (T2−
T1)] × 1000.

In the induction hardening device 200, the temperature is measured by the first temperature measuring device 281 and the second temperature measuring device 282, and the first length measuring device 291 and the second length measuring device 29 are measured.
2 is performed for the same portion over a certain period using a method described later, and the measurement data is sent to the control unit. The control unit calculates by substituting the measurement data into an equation of the elongation percentage due to only the quenching,
The calculation result is compared with a preset elongation percentage. Based on this comparison result, the control unit performs feedback control on the electric energy or the feed rate as described above. With this automatic control, the pitch error after quenching can be reduced regardless of whether the work W is made of carbon steel or alloy steel, or a cutting screw or a rolled screw.

The timing between each temperature measurement and each length measurement is determined by the first length measurement device 291 and the second length measurement device 29.
The distance s between the center of the spherical portion 295 on the front end side and the center s is, for example, 1
Assuming that the feed rate v is 20 mm / sec and the first temperature measuring device 281 and the first length measuring device 2
Five seconds after the measurement by 91, the second temperature measuring device 282
And the measurement by the second length measuring device 292 may be performed.
In this way, the state before quenching and the state after quenching are measured for the same part. Therefore, even if there is a temperature difference over the entire length of the long workpiece W,
The error due to the temperature difference can be eliminated.

According to the apparatus and method of the present invention described above, automatic control for reducing the pitch error is performed even if there is a variation in material within a lot or a variation between lots. However, it may not be possible to handle materials that are extremely different from the above models, in which case,
You just have to make a template that matches it.

[0087]

As described above, according to the first aspect of the present invention,
The induction hardening apparatus according to the present invention is a length measuring apparatus for measuring the elongation of the entire length of a ball screw as a workpiece during moving quenching, and utilizing the data of the elongation measured thereby, the workpiece to be quenched from now on. An induction hardening device having a control unit for correcting a heating amount of the part, comprising a temperature measuring device for measuring a temperature of the work before quenching and a remaining temperature of a part after the work has been hardened, Using the data of the temperature difference measured by the above, the control unit further corrects the heating amount of the work so as to reduce the pitch error, and for the part of the work to be quenched from now on. It is characterized in that it is configured to advance moving quenching.

Therefore, in the case of the induction hardening device according to claim 1 of the present invention, the data of the temperature difference is used to
Since the heating amount of the work is further corrected so as to reduce the pitch error, whether the ball screw as the work is made of carbon steel or alloy steel, or a cutting screw or a rolled screw, the pitch after quenching. It is possible to reduce errors. Therefore, the cost of the ball screw can be reduced.

An induction hardening device according to a second aspect of the present invention is an induction hardening device for moving and hardening a ball screw as a workpiece, wherein the temperature of the portion before the workpiece is hardened and the temperature immediately after the workpiece is hardened. Using a temperature measuring device that measures the temperature of the part, and using the data of the temperature measured by this, the temperature of the part before the quenching of the work and the temperature of the part immediately after the quenching of the work are substantially the same. And a control unit for performing the control described above.

Therefore, in the case of the induction hardening apparatus according to claim 2 of the present invention, control is performed such that the temperature of the portion before the quenching of the workpiece is substantially the same as the temperature of the portion immediately after the quenching of the workpiece. In this way, the effect of residual temperature of the work can be almost eliminated, so that the pitch error after quenching can be reduced regardless of whether the ball screw as the work is made of carbon steel or alloy steel, or a cutting screw or a rolled screw. Is possible. Therefore, the cost of the ball screw can be reduced.

In the induction hardening apparatus according to a third aspect of the present invention, the work according to the second aspect is characterized in that the target temperature of cooling immediately after the quenching of the work is temporarily set to a predetermined higher temperature. After the quenching is performed, it is necessary to allow the work to adapt to the environmental temperature, and the part before quenching of the work is replaced by the part immediately after quenching of the work before quenching is started. It is characterized by having a mechanism for heating until the temperature becomes substantially the same as the cooling target temperature.

Therefore, in the case of the induction hardening device according to the third aspect of the present invention, the target cooling temperature of the portion immediately after the quenching of the work is temporarily maintained at a predetermined higher temperature because of the material. Even if it is made of alloy steel that needs to be adapted to the environmental temperature, the pitch error after quenching can be accurately reduced. Therefore, the cost of the ball screw can be reduced.

The induction hardening apparatus according to claim 4 of the present invention is an induction hardening apparatus for moving and hardening a ball screw as a work, wherein a hardening mechanism for performing the induction hardening on the work, and a hardening mechanism for the hardening mechanism. A first temperature measuring device that is provided on the downstream side and measures the temperature of the work before quenching, and measures a length between predetermined pitches of a portion where the temperature is measured by the first temperature measuring device. A first length measuring device, a second temperature measuring device provided upstream of the quenching mechanism for measuring the temperature of the workpiece after quenching, and a temperature measured by the second temperature measuring device. A second length measuring device that measures the length of the portion between predetermined pitches, a moving mechanism that moves the quenching mechanism along the work, and a control unit that controls these. And the first length measuring device and the second Between the length unit is set to a predetermined distance s, the the feeding speed of the quenching mechanism using the moving mechanism is to v, the first and the first temperature measuring device
Temperature and length measurement data measured by the length measuring device, and the temperature and length measured by the second temperature measuring device and the second length measuring device after s / v of the measurement. The control unit corrects the amount of heating of the portion of the work to be quenched from now on using the data of the measurement so as to reduce a pitch error.

Therefore, in the case of the induction hardening device according to claim 4 of the present invention, the temperature and length of the same portion of the work before the work is hardened and the temperature and length after the work are hardened are determined. By measuring, the pitch error after quenching can be determined whether the ball screw as a work is made of carbon steel or alloy steel, whether it is a cutting screw or a rolled screw, and even if there is a temperature error over the entire length of the work. Since the control of the correction to be reduced can be accurately performed, the pitch error after quenching can be reduced. Therefore, the cost of the ball screw can be reduced.

A quenching control method according to claims 5 to 8 of the present invention is realized by the induction hardening apparatus according to claims 1 to 4 of the present invention. Therefore, the quenching control method according to claims 5 to 8 of the present invention has the same effects as the induction hardening apparatus according to claims 1 to 4 of the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an induction hardening apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing an induction hardening apparatus according to a fifth embodiment of the present invention.

FIG. 3 is a schematic explanatory view showing a conventional induction hardening apparatus.

FIG. 4 is a diagram for explaining the relationship between the quenching depth and the elongation of the work, and FIG. 4A is a diagram showing the relationship between the quenching depth and the elongation when the work is a cutting screw, and FIG. FIG. 3 is a diagram illustrating the relationship between the quenching depth and the elongation when the work is a rolled screw, and FIG. 3C is a diagram illustrating the quenching depth.

FIG. 5 is a schematic explanatory diagram showing a change in elongation of a work from the start of heating to the end of cooling in moving quenching.

[Explanation of symbols]

 Reference Signs List 100 induction hardening device 110 quenching mechanism 130 moving mechanism 150 rotation / elongation detection mechanism 153 length measuring unit (length measuring device) 180 temperature measuring device W work

Claims (8)

[Claims] 1. A length measuring device for measuring the elongation of the entire length of a ball screw as a workpiece during moving quenching, and heating the portion of the workpiece to be quenched by utilizing data of the elongation measured thereby. An induction hardening device having a control unit for correcting the amount, comprising a temperature measuring device for measuring the temperature of the workpiece before quenching and the remaining temperature of the quenched portion of the workpiece, Using the data of the temperature difference obtained, the control unit further corrects the heating amount of the work so as to reduce the pitch error, and moves and hardens the portion of the work to be hardened from now on. An induction hardening device characterized by being configured to advance quenching. 2. An induction hardening device for moving and quenching a ball screw as a work, a temperature measuring device for measuring a temperature of a portion of the work before quenching and a temperature of a portion of the work immediately after quenching, Using a data of the temperature measured by this, comprising a control unit that performs control to make the temperature of the part before quenching of the work and the temperature of the part immediately after quenching of the work substantially the same. An induction hardening device characterized by the following. 3. The work needs to maintain the target cooling temperature of a portion immediately after quenching of the work at a predetermined higher temperature, and then adapt the work to the environmental temperature. And a mechanism for heating a portion of the workpiece before quenching until the quenching is started until the temperature becomes substantially equal to a cooling target temperature of the part immediately after quenching of the workpiece. The induction hardening apparatus according to claim 2, characterized in that: 4. An induction hardening device for moving and quenching a ball screw as a work, a quenching mechanism for performing induction hardening on the work, and a quenching mechanism provided downstream of the quench mechanism and before quenching the work. A first temperature measuring device for measuring the temperature of the first quenching device, a first length measuring device for measuring the length of a portion where the temperature is measured by the first temperature measuring device between predetermined pitches, A second temperature measuring device provided upstream of the mechanism for measuring the temperature of the workpiece after quenching, and a length between predetermined pitches of a portion where the temperature is measured by the second temperature measuring device; A second length measuring device for measuring
A moving mechanism for moving the quenching mechanism along the work, and a control unit for controlling these; and
The distance between the first length measuring device and the second length measuring device is set to a predetermined distance s, and when the feed speed of the quenching mechanism by the moving mechanism is v, the first temperature Temperature and length measurement data measured by the measuring device and the first length measuring device, and measured by the second temperature measuring device and the second length measuring device after s / v of the measurement. The control unit corrects the heating amount of the portion of the work to be quenched from now on by using the measured temperature and length measurement data, so as to reduce a pitch error. And induction hardening equipment. 5. A method of measuring the elongation of the ball screw as a workpiece during moving quenching, and correcting the amount of heating of the portion of the workpiece to be quenched using data of the measurement result of the elongation. In the input control method, the temperature before the quenching of the work and the residual temperature of the quenched portion of the work are measured, and using the measured temperature difference data,
A quenching control method, wherein the heating amount of the work is further corrected so as to reduce a pitch error, and moving quenching is performed on a portion of the work to be quenched from now on. 6. A quenching control method for reducing a pitch error after induction hardening of a ball screw as a workpiece to be moved and quenched, wherein a temperature of a part before quenching of the workpiece and a temperature immediately after quenching of the workpiece. A quenching control method characterized by performing control to make the temperature of the portion substantially the same. 7. Due to its material, the work needs to maintain the cooling target temperature of a portion immediately after quenching of the work once at a predetermined higher temperature, and then adapt the work to the environmental temperature. The part before quenching of the work is heated until the cooling target temperature of the part immediately after quenching of the work is substantially the same as that before the start of quenching. Item 6. A quenching control method according to Item 6. 8. The length and temperature of a portion of a ball screw as a workpiece before quenching, and the length and residual temperature of the portion after quenching are measured, and the measurement results are used to quench the portion. A heating amount of the portion of the work to be corrected so as to reduce a pitch error.