JP5179203B2 - Heat treatment equipment for cylindrical metal members - Google Patents

Description

  The present invention relates to a heat treatment apparatus that performs heat treatment on an inner peripheral surface of a cylindrical metal member.

For example, linear motion guide devices such as a ball spline device and a ball screw device are known as a motion device in which a track and a movable body are engaged via rolling elements such as balls and rollers.
The linear motion guide device includes a track rail (track body) in which a rolling surface of a ball (rolling body) is formed along the longitudinal direction, a ball train that circulates infinitely, and is assembled to the track rail via the ball. It consists of a moving nut (moving body).

  Such a linear motion guide device suppresses the wear of the ball rolling surface, and from the viewpoint of maintaining the linear motion guide device accurately and over a long period of time, the track rail and the moving nut are subjected to heat treatment to obtain a predetermined It is formed to have hardness. In particular, it is important to heat-treat the ball rolling surface.

Conventionally, the component members of the linear motion guide device are generally subjected to carburizing and quenching, which requires a long processing time, resulting in a decrease in productivity and an increase in cost.
For this reason, as disclosed in Patent Document 1, it has been proposed to perform induction hardening.
JP-A-11-209844

However, due to the shape of the moving nut, which is a cylindrical metal member, it is difficult to cure only the inner peripheral surface (especially the ball rolling surface) with a general-purpose induction hardening device. For this reason, there is no choice but to carry out a carburizing treatment and carburizing and quenching, and a decrease in productivity is a problem.
In addition, in guide devices such as a ball spline device and a ball screw device, there is a demand for miniaturization, and a moving nut that is a cylindrical metal member is required to be thin. For this reason, when quenching is performed on a moving nut that is thinned in particular, there is a problem that thermal deformation occurs, distortion remains, and high accuracy of the guide device becomes difficult.

  The present invention has been made in view of the above-described circumstances, and it is possible to perform heat treatment with less residual strain on the inner peripheral surface of a cylindrical metal member, and it is possible to perform cylindrical metal with high productivity. It aims at proposing the heat processing apparatus for members.

The cylindrical metal member heat treatment apparatus according to the present invention employs the following means in order to solve the above problems.
The present invention provides a high-frequency heating unit that is inserted with a gap from the inner peripheral surface of the cylindrical metal member, and a cooling medium supplied to the gap to cool the cylindrical metal member from the inner peripheral surface side. A second cooling unit that cools the cylindrical metal member from the outer peripheral surface side by supplying a cooling medium to the outer peripheral surface of the holding member; a cooling member; a holding member that surrounds the outer peripheral surface of the cylindrical metal member; And a section.
Thereby, a heat treatment and a cooling treatment can be performed on the inner peripheral surface of the cylindrical metal member while suppressing the deformation of the cylindrical metal member by the holding member.

In addition, a rotating unit that rotates the cylindrical metal member relative to the high-frequency heating unit in a state where the high-frequency heating unit is inserted into the cylindrical metal member is provided.
Thereby, the inner peripheral surface of the cylindrical metal member can be uniformly heat-treated without unevenness.

In addition, while cooling the cylindrical metal member by the second cooling unit, the cylindrical metal member is heated by the high-frequency heating unit, and after the heating by the high-frequency heating unit is stopped, the first cooling unit A control unit that cools the cylindrical metal member is provided.
Thereby, a temperature profile can be set arbitrarily and desired heat treatment can be realized.

The cylindrical metal member is a thin member having a thickness of 10 mm or less.
In particular, in the case of a thin cylindrical metal member, deformation due to heat treatment can be suppressed.

Further, the cylindrical metal member is a moving body that moves relative to the track body via a rolling element.
Further, the cylindrical metal member is a nut member of a ball spline device.
Further, the cylindrical metal member is a nut member of a ball screw device.

According to the present invention, the following effects can be obtained.
A heat treatment with little residual strain can be performed on the inner peripheral surface of the cylindrical metal member, and a heat treatment with high productivity can be performed.
Therefore, it is possible to perform a desired heat treatment without deforming the moving body (the ball spline device or the nut member of the ball screw device) that moves relative to the raceway via the rolling element, and highly accurate motion. An apparatus can be realized.

Hereinafter, an embodiment of a heat treatment apparatus for a cylindrical metal member according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a heat treatment apparatus according to an embodiment of the present invention.
FIG. 2 is a top view and a cross-sectional view of a nut member that is an object to be heat treated.
The heat treatment apparatus 10 according to the present embodiment heat-treats the inner peripheral surface 54 of the nut member 50, and the high-frequency heating unit 12 inserted into the inner peripheral surface of the nut member 50 that is a heat-treated object, The holding member 14 that surrounds the outer peripheral surface 55 of the nut member 50, the first cooling unit 16 that cools the nut member 50 from the inner peripheral surface 54 side, and the second that cools the nut member 50 from the outer peripheral surface 55 side via the holding member 14. The cooling unit 18, the nut member 50, and the rotary table 22 that rotates around the central axis of the nut member 50, and the control unit 30 that comprehensively controls them are provided.
The main part of the heat treatment apparatus 10 excluding the control unit 30 and the like is accommodated in the chamber 11 so that radiant heat during heat treatment and cooling water W described later do not leak to the outside.

The nut member 50, which is an object to be heat treated, is placed on the turntable 22 so that the rotation axis of the turntable 22 and the center axis of the nut member 50 coincide. Specifically, the ring-shaped holding member 14 is placed on the rotary table 22 so that the rotation axis of the rotary table 22 and the central axis of the holding member 14 coincide. Then, the nut member 50 is inserted into the holding member 14.
A flange 52 is formed on one end side of the nut member 50, and the length (height) of the holding member 14 is longer than that of the nut member 50, so that the other end side of the nut member 50 rotates. The upper surface 22a of the table 22 is held away from the rotary table 22 without touching the upper surface 22a.

The holding member 14 has an inner diameter that is substantially the same as the outer diameter of the nut member 50, and is sufficiently thicker than the nut member 50. This is because by surrounding the outer peripheral surface of the nut member 50 so as to be in close contact with the holding member 14, thermal deformation of the nut member 50 is suppressed (corrected) when the nut member 50 is subjected to heat treatment.
The holding member 14 is made of a material having high thermal conductivity (iron, copper, aluminum, etc.). This is because the nut member 50 is efficiently cooled from the outer peripheral surface 55 side.

The high-frequency heating unit 12 includes a coil 12a formed in a round bar shape and a power supply unit 12b that supplies a high-frequency alternating current to the coil 12a.
The coil 12a of the high-frequency heating unit 12 is inserted with a uniform distance from the inner peripheral surface 54 of the nut member 50, which is the object to be heat treated. The length (height) of the coil 12a is formed longer than the nut member 50, and a flange 12c is provided at the root of the coil 12a. The flange 12c is brought into contact with the flange 52 of the nut member 50 so that the insertion position of the coil 12a with respect to the nut member 50 is constant.
When a high-frequency alternating current is supplied to the coil 12a that is inserted with a gap S between the inner peripheral surface 54 of the nut member 50, the conductor disposed in the vicinity of the coil 12a, that is, the nut member 50 has a high height. An eddy current having a density is generated, and the nut member 50 is heated by the Joule heat.

  In the high frequency heating, the energy per unit time supplied to the unit area of the nut member 50 is large, so that high speed heating and high temperature heating are possible. Further, since the nut member 50 itself is heated, heat loss is small and heating efficiency is large. Further, by selecting the arrangement of the coil 12a and the frequency / output of the alternating current, the nut member 50 can be locally heated, the whole can be heated, and temperature control can be easily performed. There is.

The first cooling unit 16 causes the cooling water (cooling medium) W to flow in a direction opposite to the insertion direction of the coil 12a with respect to the gap S formed between the coil 12a and the nut member 50, whereby the nut member 50 is cooled from the inner peripheral surface 54 side.
The first cooling unit 16 includes a tubular cooling jacket 16j through which the cooling water W passes, and this cooling jacket 16j is inserted from below into an opening formed at the rotation center of the turntable 22, and is held by a holding member. 14 is partially inserted. Then, the cooling water W flows from the lower side (the other end side) of the nut member 50 toward the nut member 50, whereby the cooling water W flows into the gap S formed between the coil 12 a and the nut member 50. Then, it flows out to the upper side (flange side) of the nut member 50.
Thereby, the cooling water W absorbs heat (heat exchange) from the nut member 50, and cools the nut member 50 from the inner peripheral surface 54 side.

The second cooling unit 18 cools the nut member 50 from the outer peripheral surface 55 side via the holding member 14 by flowing cooling water W to the outer peripheral surface 14b of the holding member 14 holding the nut member 50. is there.
The second cooling unit 18 includes a ring-shaped cooling jacket 18j through which the cooling water W passes, and the outer peripheral surface 14b of the holding member 14 is covered with the cooling jacket 18j, and is formed on the inner surface side of the cooling jacket 18j. The cooling water W is supplied from the plurality of holes toward the outer peripheral surface 14b of the holding member 14. The cooling water W flows vertically between the holding member 14 and the cooling jacket 18j along the outer peripheral surface 14b.
Thus, the cooling water W absorbs heat (heat exchange) from the nut member 50 via the holding member 14 and cools the nut member 50 from the outer peripheral surface 55 side.

  The cooling water W supplied from the cooling jacket 16j of the first cooling unit 16 and flowing out to the upper side of the nut member 50 and the cooling water W supplied from the cooling jacket 18j of the second cooling unit 18 and discharged to the upper and lower sides of the holding member 14 The cooling water W is respectively collected in the chamber 11, cooled by a cooling device (not shown), and then passed through the cooling jackets 16j and 18j again.

The rotary table (rotating unit) 22 rotates the nut member 50 around its central axis in a state where the nut member 50 is placed on the upper surface 22a via the holding member 14.
The nut member 50 can be uniformly heated and cooled by rotating the nut member 50 while the high-frequency heating unit 12 is operating the first cooling unit 16 and the second cooling unit 18. Yes. Therefore, a uniform metal structure can be formed on the nut member 50.

  The control unit 30 (not shown) controls the power supply unit 12b, the first cooling unit 16, the second cooling unit 18, and the rotary table 22 of the high-frequency heating unit 12 in an integrated manner. Specifically, the output / frequency / heating time of the power supply unit 12b, ON / OFF (cooling time) or flow rate of the first cooling unit 16 and the second cooling unit 18, water pressure, ON / OFF or rotation speed of the rotary table 22 The nut member 50 can be subjected to a desired heat treatment (see FIG. 3A) by controlling and adjusting the above.

A nut member (cylindrical metal member, moving body) 50 shown in FIG. 2 is an example of an object to be heat-treated in the heat treatment apparatus 10 and is a component of a ball spline apparatus 100 described later.
On the inner peripheral surface 54 of the nut member 50, for example, ten (five sets) rolling surfaces 56 for rolling a ball (see FIGS. 6 and 8) and a roller are formed along the longitudinal direction. This rolling surface 56 is subjected to heat treatment (quenching and tempering) so as to have a hardness of HV500 or higher, for example, because a load is applied via balls and rollers. Quenching is performed from the surface to a depth of about 1 to 2 mm.
The nut member 50 is, for example, carbon steel containing about 0.5% carbon C and about 1% manganese Mn.

FIG. 3 is a diagram illustrating an example of a temperature profile of the heat treatment performed by the heat treatment apparatus 10.
As shown in FIG. 3A, in the heat treatment (quenching) for the nut member 50, first, the second cooling unit 18 is operated, and the high-frequency heating unit 12 is operated at the same time or slightly delayed. At this time, the rotary table 22 is also operated.
Since the heating by the high-frequency heating unit 12 acts directly and at high speed on the nut member 50 rather than the cooling by the second cooling unit 18, the nut member 50 has a desired shape as shown in FIG. Heated to temperature.

Next, heating by the high-frequency heating unit 12 is stopped and the state is maintained for a while. Thereby, the nut member 50 is gradually cooled by the second cooling unit 18. And the 1st cooling part 16 is operated and the nut member 50 is rapidly cooled from the inner peripheral surface 54 side. Thereby, the nut member 50 can be martensiticized.
The nut member 50 is thereafter tempered (see FIG. 3B), and further subjected to grinding processing on the rolling surface 56 and the like.

FIG. 4 is a view showing the metal structure after quenching and tempering of the nut member 50.
As shown in FIG. 4, a uniform martensite structure could be formed on the inner peripheral surface 54 of the nut member 50. A good result was obtained that the occurrence of incompletely quenched structure was not observed. In particular, as shown in FIGS. 4A to 4C, it can be seen that the periphery of the rolling surface 56 closest to the coil 12 a of the high-frequency heating unit 12 was successfully heat treated.
As described above, when heat treatment is performed using the heat treatment apparatus 10, a uniform metal structure can be formed on the inner peripheral surface 54 of the nut member 50.

FIG. 5 is a diagram illustrating a dimensional change before and after the quenching process of the nut member 50. FIG. 5 shows the difference between the maximum value and the minimum value obtained by measuring the cylindricity at three locations on the inner peripheral surface 54 of the nut member 50.
As shown in FIG. 5, it can be seen that when the heat treatment apparatus 10 is used, there is less deformation than in the prior art. In the case of the conventional example, the difference between the maximum value and the minimum value of the cylindricity of the inner peripheral surface 54 of the nut member 50 is about 30 μm. On the other hand, when heat treatment is performed using the heat treatment apparatus 10, the difference between the maximum value and the minimum value of the cylindricity is improved to about 12 μm. That is, when the heat treatment apparatus 10 is used, it can be seen that the shape of the nut member 50 is maintained even after the heat treatment.
As described above, when the heat treatment is performed using the heat treatment apparatus 10, the deformation of the nut member 50 can be minimized.
Not only the cylindricity but also geometric tolerances such as roundness, straightness, flatness, etc. were improved (residual deformation was suppressed).

FIG. 6 is a view showing the ball spline device 100.
The ball spline device (motion device) 100 is assembled to the spline shaft 101 via a spline shaft (track body) 101 formed in a substantially cylindrical shape and a plurality of balls (rolling bodies) 103 formed in a substantially cylindrical shape. The outer cylinder (moving body) 102 is attached, and the outer cylinder 102 is configured to reciprocate freely around the spline shaft 101 in the axial direction.
The nut member 50 described above is used for the outer cylinder main body 104 of the outer cylinder 102.

On the outer peripheral surface of the spline shaft 101, six ball rolling surfaces 110 are formed along the axial direction. The ball 103 rolls between the ball rolling surface 110 and the outer cylinder 102 and the spline shaft 101. The load is applied between them.
Each ball rolling surface 110 is formed in a circular arc shape in which the shape in a cross section perpendicular to the longitudinal direction is a circular arc slightly larger than the spherical arc of the ball 103. These ball rolling surfaces 110 are formed symmetrically on the outer peripheral surface of the spline shaft 101 with the two ball rolling surfaces 110 as a pair.

On the other hand, the outer cylinder 102 includes a metal outer cylinder main body (nut member) 104 and a pair of end plates 105 that are screwed to both ends in the axial direction of the outer cylinder main body 104 with bolts. Both the outer cylinder main body 104 and the end plate 105 have a through hole through which the spline shaft 101 is inserted.
As described above, the outer cylinder 102 composed of the combination of the outer cylinder main body 104 and the end plate 105 is configured such that the infinite circulation path 130 on which the ball 103 rolls is formed on the inner peripheral surface of the through hole facing the spline shaft 101. It has become.

FIG. 7 is a cross-sectional view of another nut member that is a workpiece.
FIG. 8 is a view showing the ball screw device 200.
In the above-described embodiment, the nut member 50 (outer cylinder main body 104) has the inner peripheral surface 54 formed with the plurality of rolling surfaces 56 along the longitudinal direction thereof, but is not limited thereto.
That is, as shown in FIG. 7, a plurality of (multiple) rolling surfaces 56 (ball rolling grooves 210) may be formed in a spiral shape. That is, the nut member 202 of the ball screw device 200 shown in FIG. 8 may be used.

  A ball screw device (exercise device) 200 includes a screw shaft (track body) 201 and a nut member (moving body) 202 that are screwed together via a large number of balls (rolling members) 203. The ball rolling groove 210 of the ball 203 is formed in a spiral shape with a predetermined lead.

  In the nut member 202 (nut member 50), an infinite circulation path 230 on which the ball 203 rolls is formed facing the screw shaft 201, and the infinite circulation path 230 is formed to face the ball rolling groove 210. A loaded ball rolling groove 231 and an unloaded rolling groove 232 opened toward the screw shaft 201 are provided.

As described above, according to the heat treatment apparatus 10 according to the present invention, heat treatment with less distortion can be performed on the inner peripheral surface 54 of the nut member 50, and heat treatment with high productivity can be performed.
Therefore, the outer cylinder 102 (outer cylinder main body 104), the nut member 202, and the like that move relative to the raceways such as the spline shaft 101 and the screw shaft 201 via the rolling elements such as the balls 103 and 203 are deformed. A desired heat treatment can be performed without giving, and an exercise device such as the ball spline device 100 and the ball screw device 200 that performs a highly accurate (such as a straight line) exercise can be realized.

  Note that the operation procedure shown in the above-described embodiment, various shapes and combinations of the constituent members, and the like are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, although the flange type nut member has been described in the above-described embodiment, a flangeless type may be used.
Moreover, it is not limited to a cylindrical member such as a nut member, and may be, for example, a rectangular tube shape. Instead of a complete tube (cylinder) shape, for example, a member having a C-shaped section may be used.

  Further, the cylindrical member that is the object to be heat-treated does not have to be applied to a (linear) motion device such as a ball spline device or a ball screw device. When applied to other mechanical devices, the cylindrical member itself may be used.

  Moreover, the cylindrical member which is a to-be-heat-processed object should just be formed with the metal material which can be induction-heated not only in carbon steel (Fe). For example, Al, Cu, Ti, etc. may be used.

  In addition to quenching, the heat treatment may be any of tempering, normalizing, and annealing.

  Further, the nut member is not limited to being cooled rapidly with cooling water, but may be a case where cooling is performed using cooling oil or cooling gas. That is, the cooling medium is not limited to water, but may be any fluid such as other liquid or gas.

It is a schematic diagram which shows schematic structure of the heat processing apparatus for cylindrical metal members which concerns on embodiment of this invention. It is the upper side figure and sectional drawing of a nut member. It is a figure which shows an example of the temperature profile of the heat processing by a heat processing apparatus. It is a figure which shows the metal structure after the hardening process of a nut member. It is a figure which shows the dimensional change before and after the hardening process of a nut member. It is a figure showing a ball spline device. It is sectional drawing of another nut member. It is a figure which shows a ball screw apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Heat processing apparatus 12 ... High frequency heating part 14 ... Holding member 14b ... Outer peripheral surface 16 ... First cooling part 18 ... Second cooling part 22 ... Rotary table (rotating part)
50 ... Nut member (tubular metal member, moving body)
54 ... Inner peripheral surface 55 ... Outer peripheral surface 56 ... Rolling surface 100 ... Ball spline device 101 ... Spline shaft (track body)
102 ... outer cylinder (moving body)
103 ... Ball (rolling element)
104 ... outer cylinder body (nut member)
200 ... Ball screw device 201 ... Screw shaft (track body)
202 ... Nut member (moving body)
203 ... Ball (rolling element)
S ... Gap W ... Cooling water (cooling medium)

Claims (7)

A high-frequency heating unit inserted with a gap with respect to the inner peripheral surface of the cylindrical metal member;
A first cooling section for supplying a cooling medium to the gap to cool the cylindrical metal member from the inner peripheral surface side;
A holding member surrounding an outer peripheral surface of the cylindrical metal member;
A second cooling section for supplying a cooling medium to the outer peripheral surface of the holding member to cool the cylindrical metal member from the outer peripheral surface side;
A heat treatment apparatus for cylindrical metal members, comprising:   2. The cylinder according to claim 1, further comprising a rotating unit that rotates the cylindrical metal member relative to the high-frequency heating unit in a state where the high-frequency heating unit is inserted into the cylindrical metal member. Heat treatment equipment for shaped metal members.   While cooling the cylindrical metal member by the second cooling unit, the cylindrical metal member is heated by the high-frequency heating unit, and after the heating by the high-frequency heating unit is stopped, the cylindrical shape by the first cooling unit The heat treatment apparatus for cylindrical metal members according to claim 1, further comprising a control unit that cools the metal members.   The said cylindrical metal member is a thin member with a thickness of 10 mm or less, The heat processing apparatus for cylindrical metal members as described in any one of Claims 1-3 characterized by the above-mentioned.   5. The cylindrical metal member according to claim 1, wherein the cylindrical metal member is a moving body that moves relative to the track body via a rolling element. 6. Heat treatment equipment.   The said cylindrical metal member is a nut member of a ball spline apparatus, The heat processing apparatus for cylindrical metal members of Claim 5 characterized by the above-mentioned.   The said cylindrical metal member is a nut member of a ball screw apparatus, The heat processing apparatus for cylindrical metal members of Claim 5 characterized by the above-mentioned.

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