JP2008308726A - Apparatus for heating end of bar stock - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for heating ends of a bar stock, with which both ends of the bar stock that is made from a free-machining Cr-based stainless steel and is to be corrected in the next step, can be uniformly heated, while facilitating operation and easily enhancing safety. <P>SOLUTION: The apparatus 1 for heating both ends of the bar stock (m) that is made from the free-machining Cr-based stainless steel and is to be corrected in the next step, before the correcting step includes: a belt conveyor (transporting means) V which transports the bar stock (m) in a horizontal position along the diameter direction; and far-infrared heaters h1 to h4 which are arranged in the upper parts and the lower parts respectively in the vicinity of the both ends of the bar stock (m). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus for heating both ends of a rod made of a free-cutting Cr-based stainless steel that is scheduled to be corrected in the next step before such correction.

For example, a free-cutting Cr-based stainless steel rod made of SUS430, SUS436, or the like is formed into a constant diameter by hot rolling, cut into a predetermined length by an emery saw, and then bent into a straight line. Correction is made.
By the way, in the straightening process, if the temperature of the bar is low, the surface and the inside are cracked in the vicinity of both ends where the structure is hardened by local high heat at the time of cutting, due to the pressure by the straightening roll. Increases cracking sensitivity. Among these, although the crack which arose on the surface of an edge part can be detected by visual inspection, since the internal crack cannot be discriminate | determined, the bar | rod containing the said internal crack was not able to be detected.

In order to prevent straightening cracks near the ends of the bar, flames along the axial direction of the bar with respect to both end faces of the bar sent along the radial direction between the cutting step and the straightening step There has been proposed a method for processing an end surface of a rod-shaped steel material provided with a step of heating the vicinity of both end surfaces of the above-mentioned rod material to 500 ° C. or higher by a burner that jets (see, for example, Patent Document 1).
JP 2003-328033 A (pages 1 to 3, FIGS. 1 to 3)

However, in the end face processing method for the rod-shaped steel material, the heating in the vicinity of the end portion by the flame may be non-uniform even though the flame of the burner is injected toward the both end faces of the bar material. In particular, in the case of heating with a burner while stacking a plurality of bars for efficient heating, heating near the end due to the flame tends to be uneven for each bar. As a result, there has been a problem that cracks occur in the vicinity of the ends of some bars in the next straightening process, particularly in cold periods such as winter.
In addition, the burner heating method has a problem that requires strict management in terms of the management of the fuel gas flow path and the safety in the vicinity of the flame to be injected.

  The present invention solves the problems described in the background art, and can uniformly heat both ends of a free-cutting Cr-based stainless steel, which is scheduled to be corrected in the next process, and is easy to operate and safe. It is an object of the present invention to provide a rod end portion heating device that can easily improve the property.

Means for Solving the Problems and Effects of the Invention

In order to solve the above-mentioned problem, the present invention was conceived in that both ends of a bar material conveyed in a horizontal posture along the radial direction are heated by far-infrared heaters disposed above and below the rod member. It is.
That is, the rod end heating device of the present invention (Claim 1) heats both ends of a rod made of free-cutting Cr-based stainless steel, which is scheduled to be corrected in the next process, before the correction. And a far-infrared heater disposed near both ends of the rod and above and below both ends of the rod. It is characterized by having.

  According to this, when the bar material is individually conveyed in the horizontal posture and along the radial direction, the both ends of the bar material are, for example, in a range of about 10 cm from the end surface by the upper and lower far infrared heaters. , It can be heated uniformly and rapidly to about 20 ° C. to about 100 ° C. Furthermore, even when the plurality of bars stacked in a plurality of stages are conveyed in a horizontal posture and along the radial direction, uniform and quick heating can be performed for each of the plurality of end portions. Even when receiving the pressure in the centripetal direction by a plurality of correction rollers when the next process is corrected while maintaining such a heating state, it is possible to reliably prevent a conventional crack from occurring near the end. Therefore, it is possible to increase the yield in the manufacturing process of the bar made of free-cutting Cr-based stainless steel. In addition, since the far-infrared heater is used as the heating source, it is easy to operate and the safety can be easily improved.

The free-cutting Cr-based stainless steel includes, for example, SUS430, SUS436, or equivalent stainless steel, and the same kind of Cr-based stainless steel.
The transport means may be, for example, a plurality of sets of endless chains and sprockets meshed inside both ends thereof, a walking beam type transport machine composed of a plurality of movable frames and fixed frames, or endless. A plurality of sets of belts and rollers that come into contact with the inner peripheral surfaces of both ends are included.
Furthermore, the far-infrared heater has a cover having a reflection surface for reflecting the irradiated far-infrared light on the opposite side of the rod to be heated.

Further, in the present invention, at least one far-infrared heater among two sets of left and right far-infrared heaters arranged near both ends of the bar and on the upper and lower sides of the conveying means is a bar to be heated. Also included is a bar end heating device (Claim 2) which is movable along the axial direction of the bar according to the length.
According to this, even if lots with different axial lengths are transported, two sets of left and right far-infrared heaters can be easily placed on the upper and lower corners near both ends according to the length of the bar for each lot. Can be arranged. Therefore, even for rods having different lengths, it is possible to apply uniform and rapid heating to both end portions in a timely manner as described above.

Furthermore, in the present invention, the far-infrared heater has an elongated wire shape, and is disposed along the radial direction of the rod material that is conveyed in a horizontal posture by the conveying means. Claim 3) is also included.
According to this, even when the plurality of bars stacked in a plurality of stages are conveyed along the radial direction, the wires arranged along the radial direction for each of the plurality of end portions. Uniform and rapid heating can be surely performed by the far-infrared heater in a shape. In addition, since the configuration of the apparatus is simplified, the facility cost and running cost can be reduced.

In other words, the present invention includes a step of cutting a rod made of free-cutting Cr-based stainless steel formed into a constant diameter by hot rolling into a predetermined length, and a plurality of cut rods Free cutting, including a step of heating the vicinity of both ends of the plurality of bars with a far-infrared heater while conveying the rod along the radial direction, and a step of correcting the bars heated at both ends. The manufacturing method of the bar which consists of heat resistant Cr type | system | group stainless steel may also be included.
In this case, both ends of the rod made of free-cutting Cr-based stainless steel that has been formed into a constant diameter by hot rolling and cut to a predetermined length by an emery saw, etc., by the far-infrared heater, Uniform and quick heating can be performed. Therefore, even if the heated bar material at both ends is corrected in the correction process, it is possible to prevent cracks in the vicinity of both ends.

In the following, the best mode for carrying out the present invention will be described.
FIG. 1 is a perspective view showing an outline of a bar end portion heating apparatus 1 according to the present invention, and FIG. 2 is a side view at a viewing angle along the conveying direction of the bar m in the bar end portion heating apparatus 1.
As shown in FIG. 1, the rod end portion heating apparatus 1 includes a plurality of parallel sets each of which transports lots M1 to M3 in which a plurality of rods m are stacked in two stages in a horizontal posture along their radial direction. Belt conveyor (conveying means) V, and four far-infrared heaters h1 to h4 arranged near both ends of the bar m and above and below the both ends. FIG. 1 shows a state where both ends of each bar m of the lot M2 are heated by far infrared heaters h1 to h4.
The bar m is made of, for example, free-cutting Cr-based stainless steel such as SUS430 or SUS436, and has a diameter of 20 to 40 mm and a length of about 5 to 6 meters. Applied to the material.

Each set of belt conveyors V is a pair of rollers which are made endless so that the belt V made of heat-resistant rubber or resin has an oval shape in a side view and rotates while contacting at least the inner peripheral surfaces of both ends of the belt V. At least one of the rollers R is a driving roller that is rotatably connected to a power source such as a motor.
As shown in FIG. 1, the far-infrared heaters h1 to h4 have two heaters each having a linear shape, and are conveyed in a horizontal posture and along the radial direction on a plurality of sets of belt conveyors V. It is arrange | positioned along the radial direction of the bar group m concerned with respect to the vicinity of the both ends of every bar m. Moreover, the far-infrared heaters h1 to h4 are supported by covers 21 to 24 which are installed inside. The covers 21 to 24 are substantially rectangular parallelepiped and have an opening that extends toward the belt conveyor V, and the inner side surfaces thereof are reflecting surfaces that reflect far infrared rays.
1, the far-infrared heater h3 located in the upper part of the front in the figure and the cover 23 in which the far-infrared heater h3 is disposed are arranged on the axis of the bar m conveyed on the belt conveyor V. It can be moved along the direction by a mechanism described later.

As shown in the side view of FIG. 2, the bar end portion heating device 1 is disposed on the left side of a plurality of sets of belt conveyors V arranged above the floor F and along the illustrated front-rear direction. Far-infrared heaters h1 and h2 and far-infrared heaters h3 and h4 arranged on the right side are provided.
As shown on the left side of FIG. 2, far-infrared rays are provided on the flange on the belt conveyor V side of the support column 3 made of H steel standing on the floor F via a horizontal plate 13 and a support member 14 standing from now on. A cover 22 for installing the heater h2 is attached with its opening facing upward.
Further, an elevating unit 6 having a substantially U-shaped plan view is disposed in the middle of the support column 3. The elevating unit 6 has an integral horizontal piece 9 having a bearing 7 that is pin-coupled with a vertical piece 5 positioned at the upper end of the piston rod 4 that extends and contracts from the air cylinder S supported at the lower end of the column 3. The cylinder S can be moved up and down.

Further, as shown on the left side of FIG. 2, on the belt conveyor V side of the horizontal piece 9 of the elevating unit 6, a cover in which a far infrared heater h <b> 1 is installed via a bolt 8 screwed to the horizontal piece 9. 21 is attached with its opening facing downward. On the opposite side of the horizontal piece 9 of the elevating unit 6 from the conveyor V, a pair of upper and lower rollers 11 are pivotally supported by a pair of front and rear vertical pieces 10 connected to the horizontal piece 9. The four rollers 11 in total guide the elevating part 6 so that it can be moved up and down by the cylinder S along the column 3 by sandwiching the guide rail 12 fixed vertically to the outer flange of the column 3 from the front and the rear of FIG. is doing.
As shown by the dashed line arrow on the left side of FIG. 2, the air cylinder S moves the elevating unit 6 along the column 3 to convey the cover 21 having the far infrared heater h <b> 1 on the belt conveyor V. It is possible to easily adjust the end portions of the plurality of rods m to the optimum positions (heights) for heating. In addition, the raising / lowering operation of the far-infrared heater h1 and the cover 21 can be utilized also during the maintenance of the heater h1.

As shown on the right side of FIG. 2, a support column 25 made of H steel is erected on the floor F, and a base portion of a beam 30 made of H steel extending horizontally above the belt conveyor V is fixed to the upper end thereof. ing. A motor 26 is attached to the upper portion of the support column 25, and a feed screw rod 28 having a rotating shaft and a base end portion coupled to each other is disposed along the lower side of the beam 30. The beam 30 is supported via a bearing 27.
In the beam 30, a slider 29 having a female screw hole (not shown) that is screw-coupled to the feed screw rod 28 is provided with a pair of front and rear rollers 31 pivotally supported above and a plurality of rollable balls built therein. 2 (not shown), and is supported so as to be slidable along the longitudinal direction of the beam 30 (the axial direction of the bar m to be conveyed) as indicated by the horizontal dashed-dotted arrow in FIG. Yes.
The cover 23 in which the far-infrared heater h <b> 3 is installed is attached with its opening facing downward through a bolt 34 screwed to the flange 33 of the support member 32 attached to the lower side of the slider 29.

  Further, as shown on the right side of FIG. 2, the far infrared heater h <b> 4 is attached to the frames 15 and 17, which are respectively arranged in advance at predetermined positions in parallel with the belt conveyor V via support members 16 and 18. Covers 24 to be provided are individually attached with their openings facing upward. Among these, the far-infrared heater h4 and the cover 24 on the frame 17 positioned near the support column 25 are for heating the end of the relatively long bar m, and the frame positioned between the belt conveyors V and V. The far-infrared heater h4 and the cover 24 on 15 are for heating the end of a relatively short bar m. In order to position the far-infrared heater h3 and the cover 23 directly above the two far-infrared heaters h4 and the cover 24, the slider 29 is moved along the longitudinal direction of the beam 30 by the motor 26 and the feed screw rod 28. And slide.

  In FIG. 2, the two far infrared heaters h4 and the cover 24 are arranged, but three or more of them may be arranged. Further, the motor 26, the beam 30, the feed screw rod 28, the cover 23 provided with the far infrared heater h3, and the like may be moved up and down along the column 25 using the same air cylinder S as described above. Further, one far-infrared heater h4 and cover 24 are slid along the axial direction of the bar m to be transported from the lower part of the column 25 through the same beam, feed screw rod, slider and the like as the beam 30. It may be possible.

Below, the effect | action of the bar end part heating apparatus 1 mentioned above is demonstrated.
As shown in FIG. 3, hot rolling S1 is applied to a material (not shown) made of free-cutting Cr-based stainless steel such as SUS430 or SUS436, and a long bar having a diameter of 20 to 40 mm is formed. A plurality of bars m having a length of about 5 to 6 meters were obtained by a cutting step S2 in which a long bar was cut with an emery saw. At the time of such cutting, both ends of each bar m are rapidly heated to high temperature, so that the toughness of the internal metal structure is lowered.
Therefore, the rod end heating device 1 is used in a state in which a plurality of rods m are stacked in about 2 to about 10 stages according to the diameter and the both ends are substantially aligned. Then, end part heating process S3 which heats the both ends of each bar m is performed.

As shown in FIG. 4, a plurality of bar members m having a length of about 6 m are stacked in two stages and conveyed on the plurality of sets of belt conveyors V along the depth direction. The far-infrared heater h3 and the cover 23 drive the motor 26 in advance, and slide the slider 29 along the axial direction of the bar m with a rotating feed screw rod 28. It is located directly above the heater h4 and the cover 24.
As shown in FIG. 4, both ends of the plurality of bar members m conveyed in a two-layer stack on the belt conveyor V reach between the far infrared heaters h1 and h2, and between the far infrared heaters h3 and h4. And while passing between these, far infrared rays are irradiated from the far infrared heaters h1-h4 with respect to the both ends of the bar m. As a result, the far-infrared rays rapidly and uniformly permeate the entire interior including the central portion of both ends (the range from the end face to about 10 cm) of the plurality of rods m irradiated with the far-infrared rays. Therefore, both end portions can be uniformly heated in a temperature range of about 20 to 100 ° C.

Further, as shown in FIG. 5, a plurality of comparatively short bars m having a length of about 5 m are stacked in two stages and conveyed on a plurality of sets of belt conveyors V along the depth direction. There are also cases where both ends of the are heated. In this case, the far-infrared heater h3 and the cover 23 drive the motor 26 in advance, and the slider 29 is slid along the axial direction of the bar m by the rotating feed screw rod 28. As indicated by the one-dot chain line arrow, the far-infrared heater h4 disposed on the frame 15 between the conveyor belts V and V and the cover 24 are moved.
As shown in FIG. 5, both end portions of the plurality of bars m conveyed in a two-stage stack on the belt conveyor V pass between the far infrared heaters h1 and h2, and between the far infrared heaters h3 and h4. In the middle, far-infrared rays are irradiated from the far-infrared heaters h1 to h4 to both ends of each bar m. As a result, the far-infrared rays rapidly and uniformly permeate into both ends of the plurality of rods m irradiated with the far-infrared rays, so that both ends are made uniform at the same temperature as described above. Can be heated.

4 and FIG. 5, the plurality of rods m whose both ends are uniformly heated in the end heating step S3 are sequentially fed between a drum roll and a drum roll (not shown) as shown in FIG. And is sent to a correction step S4 for correcting bending or the like. While undergoing such correction, by maintaining both ends of each bar m at at least + 20 ° C., the impact value at both ends can be maintained at about 20 J / cm ² or more. By keeping both ends of the bar m at + 40 ° C., the impact value can be kept at about 40 J / cm ² or more.
As a result, in the straightening step S4, it is possible to almost eliminate the occurrence of cracks at both ends of each bar m or the formation and incorporation of cracks inside.
Therefore, the yield of the bar m made of free-cutting Cr-based stainless steel can be increased. Moreover, since the far infrared heaters h1 to h4 are used in the end heating step S3, the heating efficiency is good, the operation is easy, and the safety is excellent.

  Incidentally, a plurality of rods m made of SUS430 and having a diameter of 20 mm and a length of 5 meters were prepared, and the same number was divided into two sets and aligned along the radial direction under the same conditions. Of these, both ends of each bar m in one set were heated to about 40 ° C. using the far-infrared heaters h1 to h4, and then passed through the correction rolls in order to correct. No cracks occurred in m. On the other hand, the both ends of each bar m in the other set were heated to about 500 ° C. with a conventional burner and then corrected under the same conditions between the same correction rolls as described above. Cracks occurred in several percent. Such cracking occurred at a high rate especially in winter. Such an experiment also confirmed the effect of using the heating device 1 of the present invention.

The present invention is not limited to the embodiment described above.
For example, the pair of left and right far infrared heaters h1 to h4 of the left and right heaters h1 and h2 on the left side and the heaters h3 and h4 on the right side are displaced from each other along the conveying direction of the plurality of bars m. It is good also as an arranged form.
The far-infrared heaters h1 to h4 are two linear shapes in a plan view, but may be formed of, for example, only one that has a substantially U shape in a plan view.
Further, a metal mesh belt can be used for the conveying means.
In addition, when heating both ends of a relatively large-diameter bar, the far-infrared heaters h1 to h4 are transported in a state where the bars are aligned one by one on the belt conveyor V or the like. It is also possible to heat by.

The perspective view which shows the outline of the bar end part heating apparatus of this invention. The side view of the viewing angle along the conveyance direction of the bar in the said bar end part heating apparatus. The flowchart which shows the manufacturing process of the bar used as the object of this invention. Schematic which shows the effect | action of the said rod end part heating apparatus. Schematic which shows the effect | action of the said bar | plate end part heating apparatus with respect to bar | burr of different length.

Explanation of symbols

1 …………… Bar end heating device m ………… Bar V …………… Belt conveyor (conveying means)
h1-h4 ... Far-infrared heater

Claims (3)

A device that heats both ends of a rod made of free-cutting Cr-based stainless steel that is scheduled to be corrected in the next step, before the correction,
Conveying means for conveying the bar in a horizontal posture along its radial direction;
A far-infrared heater disposed near both ends of the bar and above and below each of the both ends.
A bar end heating device characterized by the above. Of the two sets of left and right far infrared heaters arranged near both ends of the bar and above and below, at least one far infrared heater depends on the length of the bar to be heated. It is possible to move along the axial direction of the bar,
The bar end portion heating device according to claim 1. The far-infrared heater has an elongated linear shape and is arranged along the radial direction of the bar material conveyed in a horizontal posture by the conveying means.
The bar end heating device according to claim 1 or 2, wherein

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