Pipe material quenching method and quenching device

Abstract

When multiple pipe materials are continuously transported in contact with each other on a transport path, the arrival of the front end (downstream end) of the pipe material is reliably detected, and based on that detection information, heat treatment is accurately performed using a heating coil section only on the part of the pipe material to be quenched. [Solution] A first group of pipe materials that are coaxially abutted on the upstream side of the pipe material to be quenched and a second group of pipe materials that are coaxially abutted on the upstream side of the first upstream pipe material are transported in an eccentric state, speed information that is information that correlates with the transport speed of the first group of pipe materials and / or the second group of pipe materials is detected by a speed detection means, and a step portion created by the eccentric state between the first group of pipe materials and the second group of pipe materials is detected by a displacement detection means, and the start time and duration of the heating treatment by the heating coil portion are calculated based on the speed information obtained by the speed detection means, the detection timing of the step portion obtained from the displacement detection means, and the distance between the heating coil portion and the displacement detection means, and heating treatment is performed on a specified area of ​​the pipe material to be quenched.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for quenching a pipe material, in which a plurality of pipe materials are quenched by passing them continuously at a predetermined speed through a heating coil section and a cooling section installed on a conveying path. [Background technology]

[0002] FIG. 6 is a schematic perspective view showing an example of the configuration of an automobile door impact beam (DIB), in which a predetermined region (see the shaded area) of a tubular material constituting the DIB is quenched. The quenched region of the tubular material achieves effects such as improved mechanical properties, such as mechanical strength, durability, hardness, and / or abrasion resistance, thereby enhancing the DIB's ability to prevent deformation of the passenger compartment during a collision. While FIG. 6 illustrates a tubular material quenched only in a predetermined region, quenching may be performed over the entire tubular material.

[0003] On the other hand, the ends of the pipe material constituting the DIB are often crushed into a flat plate as shown in FIG. 7 (see the area surrounded by the thick dashed line) or crushed to form beveled corners as disclosed in Patent Document 1, for purposes such as welding to a bracket called an "extension" and / or preventing the end from piercing the outer plate of a door during a collision. From the perspective of reducing the processing load when crushing the ends of the pipe material and avoiding the occurrence of defects such as cracks, it is desirable that the ends of the pipe material constituting the DIB are not hardened. Furthermore, pipe material that is hardened only in a specified region and not in other regions is used not only for DIBs but also in various applications requiring high mechanical properties.

[0004] Therefore, in the technical field, there is known a quenching device for quenching a pipe material continuously. This conventional device is configured to continuously quench a plurality of pipe materials along a linear conveying path while being in contact with each other using a conveying mechanism, and to pass each pipe material through a heating coil installed on the linear conveying path at a constant speed, thereby continuously quenching the entire length or a predetermined region of each pipe material. The quenching process is performed by a heating process followed by a rapid cooling process immediately after the heating process. In a continuous quenching device, control of the position (timing) of the heating process and the amount of heat are particularly important.

[0005] When it is desired to quench only a predetermined region (a certain range in the axial direction) of a pipe material using the above-mentioned quenching device, it is necessary to energize the heating coil only while the portion of the pipe material to be quenched (hereinafter, sometimes referred to as the "portion to be quenched") to be quenched (hereinafter, sometimes referred to as the "pipe material to be quenched") arrives at the heating coil and passes through the heating coil. Therefore, it is necessary to accurately grasp the conveying position of the pipe material to be quenched, and from that position information and conveying speed information, predict the timing when the portion to be quenched will arrive at the heating coil, start energizing the heating coil at that timing, and maintain the energization for a certain period of time.

[0006] For example, in the invention described in Patent Document 2, multiple pipe materials are transported on a transport path consisting of a transport roller mechanism, and the arrival of the front end (downstream end) of the upstream pipe material is detected by a proximity switch LS1.Based on this detection information, the time T1 at which the front end of the upstream pipe material arrives in front of the heating coil is calculated, a timer is started, and current is applied to the heating coil after time T1. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 5-213063 [Patent Document 2] Patent No. 3643420 Summary of the Invention [Problem to be solved by the invention]

[0008] However, it is extremely difficult to detect the contact points between coaxially abutting pipes using a proximity switch, resulting in frequent false detections. The invention described in Patent Document 2 also incorporates control of the pipe conveying speed individually before the pipe reaches the heating coil, creating a gap between the upstream and downstream pipes in the conveying direction. This increases the likelihood of an error occurring between the calculated energization timing of the heating coil and the actual energization timing of the heating coil (the timing when the heated part reaches the heating coil). Such an error in energization timing results in a misalignment of the part to be hardened in the axial direction of the pipe, making it difficult to accurately determine the energization timing to coincide with the timing when the part to be hardened reaches the heating coil.

[0009] In view of the above-mentioned problems, one object of the present invention is to provide a method and apparatus for quenching pipe materials, which can reliably detect the arrival of the front end (downstream end) of a pipe material when a conveying mechanism continuously conveys multiple pipe materials in contact with each other on a conveying path, and based on that detection information, can accurately apply heat treatment using a heating coil only to the part of the pipe material to be quenched. [Means for solving the problem]

[0010] A quenching method for pipes that achieves the above object involves transporting a plurality of pipes, each with its end abutting against another, along a conveying path at a predetermined speed, and applying current to a heating coil section installed on the conveying path for only a first period from a first point in time, thereby subjecting a predetermined first region of the pipe to be quenched to a heat treatment. In this quenching method, the pipes to be quenched are conveyed in an eccentrically abutting relationship with the upstream end of a first pipe group, which is a group of pipes abutting each other approximately coaxially upstream of the pipe to be quenched, and the downstream end of a second pipe group, which is a group of pipes abutting each other approximately coaxially upstream of the first pipe group. Speed ​​information, which is information correlated with the conveying speed of the first pipe group and / or the second pipe group, is detected by a speed detection means. Furthermore, a step portion caused by the eccentricity between the first and second pipe material groups is detected by a displacement detection means. In addition, a first time point and a first period are calculated based on the speed information obtained by the speed detection means, a second time point when the step portion is detected by the displacement detection means, and a first distance between the heating coil portion and the displacement detection means in the pipe material conveying direction, and a quenching process is performed on a first region of the pipe material to be quenched.

[0011] According to this method, the timing at which the front end of the pipe material located at the downstream end of the second pipe material group reaches the heating coil can be accurately calculated based on the speed information, which is information correlated with the pipe material conveying speed detected by the speed detection means, the second time point, which is the timing at which the step portion (i.e., the downstream end of the second pipe material group) is detected by the displacement detection means, and the first distance, which is the distance between the heating coil portion and the displacement detection means in the pipe material conveying direction. Therefore, it is possible to eliminate errors in detecting the timing at which the downstream end (step portion) of the second pipe material group reaches the displacement detection means, and to eliminate discrepancies between the calculated start timing of the heat treatment (the calculated timing at which current begins to flow through the heating coil portion) and the timing at which the pipe material to be quenched arrives at the heating coil portion and the heat treatment should begin (the timing at which current begins to flow through the heating coil), thereby enabling accurate heat treatment to be performed over a desired range (first region) of the pipe material to be quenched.

[0012] The conveying path also includes an upstream conveying path and a downstream conveying path offset downward in the vertical direction from the upstream conveying path. When the most downstream pipe material (hereinafter, sometimes referred to as the "second upstream pipe material") among the plurality of pipe materials constituting the second pipe material group conveyed on the upstream conveying path falls onto the downstream conveying path, the pipe material separates from the second pipe material group and joins the first pipe material group, becoming the most upstream pipe material (hereinafter, sometimes referred to as the "first upstream pipe material") among the plurality of pipe materials constituting the first pipe material group, and a step portion may be formed at the abutment portion between the upstream end of the first pipe material group and the downstream end of the second pipe material group.

[0013] With the above-described configuration of the transport path, a difference in height appears between the surfaces of the first upstream pipe material and the second upstream pipe material, forming a step at the contact point between the rear end (upstream end) of the first pipe material group and the front end (downstream end) of the second pipe material group. Therefore, the position of the front end (downstream end) of the second pipe material group can be reliably detected by the displacement detection means.

[0014] Furthermore, a second period may be provided in which the intensity of the heat treatment applied to the tubular material to be quenched by the heating coil unit is increased at a predetermined rate over a predetermined period immediately before the start of the first period, and / or a third period may be provided in which the intensity of the heat treatment applied to the tubular material to be quenched by the heating coil unit is decreased at a predetermined rate over a predetermined period immediately after the end of the first period. For example, in the second period, the intensity of the heat treatment applied to the tubular material to be quenched by the heating coil unit can be increased at a predetermined rate by increasing the intensity of the current applied to the heating coil unit (device output) at a predetermined rate. On the other hand, in the third period, the intensity of the heat treatment applied to the tubular material to be quenched by the heating coil unit can be decreased at a predetermined rate by decreasing the intensity of the current applied to the heating coil unit at a predetermined rate.

[0015] By providing the second and / or third periods as described above, a region where the intensity of the heat treatment gradually changes can be provided between the heat-treated and non-heat-treated regions of the pipe material, which reduces the risk of problems such as crushing and / or breaking of the pipe material caused by stress concentration at the boundary between the quenched and non-quenched regions of the pipe material, for example, when excessive stress acts on the pipe material.

[0016] Furthermore, the heat-treated pipe material to be quenched may be cooled by a cooling section provided in the downstream conveying path downstream of the heating coil section.

[0017] By installing a cooling section in this manner, the part to be quenched (the part of the pipe material to be quenched that has been subjected to heat treatment) can be cooled quickly and reliably immediately after the heat treatment, thereby achieving an effective quenching effect.

[0018] In addition, multiple cooling sections may be provided on the downstream conveying path downstream of the heating coil section, and the quenched pipe material that has been subjected to heat treatment may be conveyed or supported by a conveying mechanism or support mechanism arranged between adjacent cooling sections.

[0019] By arranging a conveying mechanism or support mechanism between adjacent cooling sections as described above, even pipe materials that are shorter than the distance between adjacent cooling sections can be sufficiently cooled by multiple cooling sections without falling off the conveying path.

[0020] A quenching device that achieves the above object transports a plurality of tubular materials, each having its end abutting against another, along a transport path at a predetermined speed, and when one of the tubular materials passes through a heating coil section installed on the transport path, the heating coil section is energized for only a first period from a first point in time, which is a predetermined timing, thereby performing a heat treatment on a first region of the tubular material to be quenched. The quenching device further includes a transport path, a speed detection means, a displacement detection means, and a calculation means. The transport path transports the tubular material to be quenched while abutting the upstream end of a first group of tubular materials, which is a group of tubular materials abutting each other approximately coaxially on the upstream side of the tubular material, with the downstream end of a second group of tubular materials, which is a group of tubular materials abutting each other approximately coaxially on the upstream side of the first group, in an eccentric state. The speed detection means detects speed information that is information correlated with the transport speed of the first group of tubular materials and / or the second group of tubular materials. The displacement detection means detects a step caused by the eccentricity between the first and second pipe groups. The calculation means calculates the first time point and first period based on the speed information obtained by the speed detection means, the second time point when the step is detected by the displacement detection means, and the first distance between the heating coil and the displacement detection means in the pipe conveying direction.

[0021] According to this quenching device, the calculation means can accurately calculate the timing at which the front end of the pipe located at the downstream end of the second pipe group reaches the heating coil based on the speed information, which is information correlated with the pipe material conveying speed detected by the speed detection means, the second time point, which is the timing at which the step portion (i.e., the downstream end of the second pipe material group) is detected by the displacement detection means, and the first distance, which is the distance between the heating coil and the displacement detection means in the pipe material conveying direction. Therefore, it is possible to eliminate errors in detecting the timing at which the downstream end (step portion) of the second pipe material group reaches the displacement detection means, and to eliminate discrepancies between the calculated start timing of the heat treatment (the calculated timing at which current begins to flow through the heating coil) and the timing at which the pipe material to be quenched arrives at the heating coil and the heat treatment should begin (the timing at which current begins to flow through the heating coil), thereby enabling accurate heat treatment to be performed over a desired range (first region) of the pipe material to be quenched.

[0022] The conveying path may also include an upstream conveying path and a downstream conveying path offset downward in the vertical direction from the upstream conveying path, and when the most downstream pipe material (second upstream pipe material) of the multiple pipe materials constituting the second pipe material group conveyed on the upstream conveying path falls onto the downstream conveying path, the pipe material separates from the second pipe material group and joins the first pipe material group, becoming the most upstream pipe material (first upstream pipe material) of the multiple pipe materials constituting the first pipe material group, and a step portion may be formed at the abutment portion between the upstream end of the first pipe material group and the downstream end of the second pipe material group.

[0023] With the above-described configuration of the transport path, a difference in height appears between the surfaces of the first upstream pipe material and the second upstream pipe material, forming a step at the contact point between the rear end (upstream end) of the first pipe material group and the front end (downstream end) of the second pipe material group. Therefore, the position of the front end (downstream end) of the second pipe material group can be reliably detected by the displacement detection means.

[0024] Furthermore, a second period may be provided in which the intensity of the heat treatment applied to the tubular material to be quenched by the heating coil section is increased at a predetermined rate over a predetermined period immediately prior to the start of the first period, and / or a third period may be provided in which the intensity of the heat treatment applied to the tubular material to be quenched by the heating coil section is decreased at a predetermined rate over a predetermined period immediately after the end of the first period. For example, in the second period, the intensity of the current applied to the heating coil section can be increased at a predetermined rate, while in the third period, the intensity of the current applied to the heating coil section can be decreased at a predetermined rate, thereby decreasing the intensity of the heat treatment applied to the tubular material to be quenched by the heating coil section.

[0025] By providing the second and / or third periods as described above, a region where the intensity of the heat treatment gradually changes can be provided between the heat-treated and non-heat-treated regions of the pipe material, which reduces the risk of problems such as crushing and / or breaking of the pipe material caused by stress concentration at the boundary between the quenched and non-quenched regions of the pipe material, for example, when excessive stress acts on the pipe material.

[0026] In addition, the heat-treated pipe material may be cooled by a cooling section provided on the downstream conveying path downstream of the heating coil section. By providing a cooling section in this manner, the portion to be quenched (the portion of the pipe material that has been quenched) can be cooled quickly and reliably immediately after the heat treatment, thereby achieving an effective quenching effect. [Effects of the Invention]

[0027] According to the quenching method for pipe material of the present invention, when a conveying mechanism continuously conveys multiple pipe materials in contact with each other on a conveying path, it is possible to reliably detect the arrival of the front end (downstream end) of the pipe material, and based on that detection information, it is possible to accurately apply heat treatment using a heating coil section only to the part of the pipe material to be quenched.

[0028] According to the pipe material quenching device of the present invention, when a conveying mechanism continuously conveys multiple pipe materials in contact with each other on a conveying path, it is possible to provide a pipe material quenching device that can reliably detect the arrival of the front end (downstream end) of the pipe material, and based on that detection information, can accurately apply heat treatment using a heating coil section only to the part of the pipe material to be quenched. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a schematic side view illustrating the configuration of a quenching device for a tube material according to a first embodiment of the present invention. [Figure 2] 2 is a schematic side view illustrating the configuration of a pipe material after quenching treatment according to the first embodiment of the present invention. FIG. [Figure 3] 1A and 1B are schematic side and top views of the vicinity of an end of a pipe material having an end that has been flattened into a plate. [Figure 4] FIG. 10 is a schematic diagram illustrating the configuration of the vicinity of a cooling section provided in a quenching device for a tube material according to a preferred third embodiment of the present invention. [Figure 5] 10A to 10C are schematic three-view diagrams illustrating the configuration of a support mechanism disposed between a plurality of cooling sections included in a quenching device for a tube material according to a preferred third embodiment of the present invention. [Figure 6] 1 is a schematic perspective view showing an example of the configuration of a door impact beam (DIB) of an automobile. FIG. [Figure 7] FIG. 2 is a schematic perspective view showing an example of the configuration of the end portion of a pipe material that constitutes a DIB. DETAILED DESCRIPTION OF THE INVENTION

[0030] A preferred embodiment of the present invention will be described below with reference to Fig. 1. In this first embodiment, in consideration of the posture of the quenching apparatus for pipe materials during installation and operation, the top of the drawing is the top of the apparatus, the left-right direction of the drawing is the horizontal direction of the apparatus and the conveying direction, and the pipe materials are conveyed from right to left. In other words, the right side of the drawing is the upstream side in the conveying direction of the pipe materials.

[0031] (First embodiment) FIG. 1 is a schematic side view showing the configuration of a quenching apparatus 1 for tubular materials according to a first embodiment of the present invention. The quenching apparatus 1 includes a conveying path 2, a heating coil unit 9, a speed detection unit 10, a displacement detection unit 11, and a calculation unit (not shown). The conveying path 2, which is composed of multiple rollers 13, is arranged horizontally and attached to the upper surface of the apparatus body (not shown). The rollers 13 are driven and controlled by a drive unit (not shown). The multiple rollers 13 have rotation axes perpendicular to the conveying direction, and by rotating, convey the tubular materials 5 placed on the conveying path 2 downstream. Such roller-type conveying mechanisms are well known in continuous quenching apparatuses, and therefore will not be described here. The conveying path 2 is horizontally installed in an operating state, and multiple tubular materials 5 are conveyed on the conveying path 2 from right to left in the figure (i.e., from upstream to downstream) at a predetermined constant speed with their end faces in the axial direction abutting and in close contact with each other. The number of pipe materials 5 continuously transported on the transport path 2 is not particularly limited, but the minimum number in this embodiment is preferably four, as shown in FIG.

[0032] The conveying path 2 includes an upstream conveying path 3 and a downstream conveying path 4. The downstream conveying path 4 is disposed offset vertically downward from the upstream conveying path 3. In other words, the downstream conveying path 4 and the upstream conveying path 3 are disposed parallel and horizontally. The offset amount is determined based on the minimum pipe eccentricity amount that allows the displacement detection means 11 (described later) to reliably detect the step portion 14. The offset direction may be oblique to the vertical, but a vertical offset is preferable to ensure accurate dropping of the pipe material 5. In FIG. 1, the pipe material 5 located most downstream among the multiple pipe materials 5 (i.e., the second pipe material group) transported on the upstream conveying path 3 is the second upstream pipe material 8, and the pipe material 5 located most upstream among the multiple pipe materials 5 (i.e., the first pipe material group) transported on the downstream conveying path 4 is the first upstream pipe material 7. The first upstream pipe material 7 and each pipe material 5 downstream thereof are in approximately coaxial contact with each other, and the second upstream pipe material 8 and each pipe material 5 (not shown) upstream thereof are also in approximately coaxial contact with each other. As the second upstream pipe material 8 is transported on the upstream conveying path 3 and falls onto the downstream conveying path 4, it becomes a new first upstream pipe material 7, and a step portion 14 is formed between the upstream end (rear end) of the new first upstream pipe material 7 and the downstream end (front end) of the new second upstream pipe material 8. In other words, step portions 14 are formed sequentially at the abutment portion between the upstream end of the first pipe material group and the downstream end of the second pipe material group. The upstream end of the first upstream pipe material 7 and the downstream end of the second upstream pipe material 8 form an abutment portion where they abut against each other in an eccentric state.

[0033] In the quenching apparatus 1 illustrated in FIG. 1, a speed detection means 10 is provided on the upstream conveying path 3 to detect the actual speed (actual conveying speed value) of the second upstream pipe material 8 as speed information that is information correlated with the conveying speed of multiple pipe materials 5 (second pipe material group) conveyed on the upstream conveying path 3. In this embodiment, the speed detection means 10 is provided so as to be rotatable in contact with the upper surface of the second upstream pipe material 8, and detects the conveying speed of the conveyed second upstream pipe material 8. Specifically, the speed detection means 10 is composed of a driven rotating part that contacts the surface of the second upstream pipe material 8 and an encoder part driven by the driven rotating part, and outputs a signal corresponding to an angular velocity or angular acceleration that is correlated with the actual speed (actual conveying speed value) detected by the encoder to a calculation means (not shown), and the calculation means calculates the conveying speed of the second upstream pipe material 8 based on the signal. It should be noted that the speed detection means 10 is not limited to this method, and for example, an encoder may be built into and / or linked to the roller 13, or a non-contact magnetic and / or optical speed detection means may be used.

[0034] In addition, a displacement detection means 11 is provided on the upstream conveying path 3 near the top surface of the second upstream tubular material 8, and detects a step 14 that occurs at the contact surface between the conveyed second upstream tubular material 8 and the first upstream tubular material 7. Specifically, a proximity sensor or laser displacement sensor is used as the displacement detection means 11 to detect when the second upstream tubular material 8 falls from the upstream conveying path 3 to the downstream conveying path 4 and becomes the first upstream tubular material 7, forming a space directly below the displacement detection means 11, or when a tubular material 5 that has subsequently become the front end (downstream end) of the new second upstream tubular material 8 reaches directly below the displacement detection means and fills the space, and outputs a corresponding output signal to a calculation means (not shown). In response to this output signal, the calculation means generates position information that includes the timing (second time point) when the front end of the second upstream tubular material 8 arrives directly below the displacement detection means 11.

[0035] In this way, the displacement detection means 11 in this embodiment can recognize the arrival of the front end of the second upstream pipe 8 not by the abutment surface (line) between the pipes but by the external shape of the step portion 14, thereby significantly reducing the possibility of erroneous detection. Note that the detection of the step portion 14 is not limited to the method in this embodiment described above, and for example, the step shape itself may be detected using an image recognition device or the like.

[0036] The calculation means (not shown) calculates the required period for the second upstream pipe material 8 (front end) to reach the heating coil section 9 using the transport speed of the second upstream pipe material 8 calculated from the speed information detected by the speed detection means 10, the second time point as position information detected by the displacement detection means 11, and the distance α between the step portion 14 and the heating coil section 9. The calculation means then calculates the time when the required period has elapsed since the time when the step portion 14 is detected by the displacement detection means 11 (second time point), i.e., the time when the front end (downstream end) of the second upstream pipe material 8 reaches the heating coil section 9 (first time point), and the period (heating period = first period) during which the quenched portion 15 (the portion of the quenched pipe material 6 that needs to be quenched) passes through the heating coil section 9 to obtain the desired quenching range. Then, the calculation means applies electricity to the heating coil section 9 only from the calculated first time point through the first period, thereby subjecting the quenched portion 15 of the quenched pipe material 6 to a heat treatment.

[0037] Furthermore, for example, in order to increase the uniformity of the quenching treatment for the quenched portion 15 of the quenched pipe material 6, the quenching device 1 may be configured to transport the pipe material 5 entering the quenching treatment section consisting of the heating coil section 9 and the cooling section 12 while rotating it around its axis, as illustrated by the thick dashed arrow in Figure 1.

[0038] Fig. 2 is a schematic diagram illustrating the configuration of a tubular material 6 to be quenched that has been heat treated as described above. In the tubular material 6 to be quenched illustrated in Fig. 2, heat treatment has been applied to a quenched portion 15, which is a region located on the downstream end (front end) side of the tubular material 6 to be quenched. The size of the dimension (length) β in the conveying direction (longitudinal direction) of this quenched portion 15 is determined by the length of the first period, which is the period during which current is applied to the heating coil portion 9, and the conveying speed of the tubular material 6 to be quenched (i.e., the conveying speed of the second upstream tubular material 8).

[0039] As mentioned above, the speed detection means detects speed information which is information correlated with the conveying speed of the first pipe group and / or the second pipe group. Therefore, in the above explanation, the displacement detection means 11 was provided in the upstream conveying path 3 so as to be close to the top surface of the second upstream pipe 8 (included in the second pipe group), but the displacement detection means 11 may also be provided in the downstream conveying path 4 so as to be close to the top surface of the first upstream pipe 7 (included in the first pipe group).

[0040] Furthermore, in the above explanation, the actual speed (actual conveying speed value) of the second upstream tubular material 8 calculated by the calculation means based on the output signal from the speed detection means 10 is used to determine the first point in time, which is the timing to start supplying current to the heating coil section 9, and the first period, which is the period during which current is supplied to the heating coil section 9. However, as mentioned above, the speed detection means detects speed information, which is information correlated with the conveying speed of the first tubular material group and / or the second tubular material group. Therefore, as another calculation method in the calculation means, if the speed detection means 10 is an encoder, the first point in time and the first period may be determined without converting the pulse signal output from the encoder into a conveying speed.

[0041] For example, the number of pulse signals detected after the forward end (downstream end) of the second upstream pipe material 8 reaches the displacement detection means 11 is calculated to determine whether the pipe material's transport distance corresponds to the distance α between the stepped portion 14 and the heating coil unit 9. At the point (=first point) when that number of pulse signals is reached, the heating coil unit 9 is energized to begin heating the portion 15 to be quenched (extending from the downstream end (front end) of the pipe material 6 to be quenched, as illustrated in FIG. 2 ). If there is a certain distance between the downstream end (front end) of the portion 15 to be quenched and the downstream end (front end) of the pipe material 6 to be quenched (i.e., they are separated), the number of pulse signals corresponding to that distance can be added. Furthermore, for the length β of the portion 15 to be quenched, the heating coil unit 9 can be energized continuously until the corresponding number of pulse signals is reached. That is, in this case, the speed detection means detects pulse signals as speed information, which is information correlated with the transport speed of the first and / or second pipe material groups. Furthermore, the speed information detected by the speed detection means is not limited to the above, and is not particularly limited as long as it is information that correlates with the conveying speed of the first pipe group and / or the second pipe group.

[0042] The heating coil unit 9 is installed in the downstream conveying path 4, and when the tubular material 6 to be quenched passes through it at a constant speed, current is applied at a predetermined timing (first time point) and continues to be applied for a predetermined period (first period). This makes it possible to obtain the quenched portion 15 that has been heat-treated over a predetermined region β.

[0043] In this way, the calculation means can accurately calculate the first time point, which is the time point when the portion of the pipe material to be quenched reaches the heating coil, based on the pipe material speed information detected by the speed detection means, position information including the second time point when the step formed at the abutment between the first pipe material group and the second pipe material group detected by the displacement detection means, and the first distance, which is the distance between the heating coil and the displacement detection means in the pipe material conveying direction. This eliminates misdetection of the time point when the downstream end (step) of the second pipe material group reaches the displacement detection means, and eliminates discrepancies between the calculated start time of the heat treatment (the calculated time point when current begins to flow through the heating coil) and the time when the pipe material to be quenched reaches the heating coil and the heat treatment should begin (the time point when current begins to flow through the heating coil), allowing accurate heat treatment to be performed over the desired range (first region) of the pipe material to be quenched.

[0044] (Second embodiment) As described above with reference to FIG. 6 , a predetermined region of a tubular material constituting an automobile door impact beam (DIB) is quenched. The quenched region of the tubular material achieves effects such as improved mechanical properties, such as mechanical strength, durability, hardness, and / or abrasion resistance, thereby enhancing the DIB's ability to prevent deformation of the vehicle interior during a side collision. Meanwhile, the ends of the tubular material constituting the DIB are often crushed into a flat plate, as shown in FIG. 7 , or crushed to form beveled corners, as disclosed in Patent Document 1. Therefore, in order to reduce the processing load when crushing the ends of the tubular material and to avoid defects such as cracks, the ends of the tubular material constituting the DIB are not quenched. As a result, when excessive stress acts, for example, during a vehicle collision, stress may concentrate at the boundary between the quenched and unquenched regions of the tubular material, potentially resulting in problems such as crushing and / or fracture of the tubular material.

[0045] The problem of stress concentration at the boundary between the quenched and unquenched regions of the pipe material as described above is not limited to the pipe material that constitutes the DIB, but is a common problem for various pipe materials that have both quenched and unquenched regions. From the perspective of reducing this problem, it is preferable to provide a region (gradual change region) where the strength of the quenching treatment gradually changes between the quenched and unquenched regions of the pipe material.

[0046] Therefore, in the quenching device for pipe material according to the second embodiment of the present invention, a second period is provided in which the intensity of the heat treatment applied to the pipe material to be quenched by the heating coil section is increased at a predetermined rate over a predetermined period immediately before the start of the first period, and / or a third period is provided in which the intensity of the heat treatment applied to the pipe material to be quenched by the heating coil section is decreased at a predetermined rate over a predetermined period immediately after the end of the first period.

[0047] Figure 3 is a schematic side view (a) and a top view (b) of the vicinity of the end of a pipe material having an end crushed into a flat plate, like the pipe material described with reference to Figure 7. The pipe material illustrated in Figure 3(a) has a region R1 that has been quenched, and a region R2 that has not been quenched remains near the end, and a region R3 is provided between regions R1 and R2, which is a gradual change region in which the strength of the quenching treatment gradually decreases as one moves from the region R1 side to the region R2 side.

[0048] Therefore, even if the region R4 between the quenched region R1 and the end portion is crushed by press processing as illustrated in Figure 3(b), the risk of problems such as crushing and / or breaking of the pipe material can be reduced.

[0049] Depending on the intended use of the pipe material, the gradual change region may be located downstream (toward the front end) of the quenched portion of the pipe material by providing a second period during which the intensity of the heat treatment applied by the heating coil to the quenched pipe material is increased at a predetermined rate over a predetermined period immediately prior to the start of the first period during which the intended heat treatment is applied to a predetermined region (first region) of the pipe material. Alternatively, the gradual change region may be located upstream (toward the rear end) of the quenched portion of the pipe material by providing a third period during which the intensity of the heat treatment applied by the heating coil to the quenched pipe material is decreased at a predetermined rate over a predetermined period immediately following the end of the first period. Furthermore, the gradual change region may be located downstream (toward the front end) and upstream (toward the rear end) of the quenched portion of the pipe material by providing a second period and a third period before and after the first period, respectively.

[0050] The intensity of the heat treatment of the tubular material to be quenched by the heating coil can be changed by controlling the strength of the current applied to the heating coil (the voltage or current applied to the heating coil). For example, during the second period, the strength of the current applied to the heating coil can be increased at a predetermined rate. During the third period, the strength of the current applied to the heating coil can be decreased at a predetermined rate. Furthermore, the strength of the current applied to the heating coil and / or the length of the current application period must be adjusted, taking into account various conditions, such as the oscillator output, rise time, and / or length of the heating coil (the dimension of the heating coil in the direction of transport of the tubular material) when the heating coil is energized.

[0051] Furthermore, the rate at which the heat treatment intensity (the strength of the current applied to the heating coil) is increased during the second period can be set appropriately depending on, for example, the length of the gradual change region to be provided in the tubular material to be quenched and the transport speed of the tubular material to be quenched. Even if the heat treatment intensity (the strength of the current applied to the heating coil) is increased from zero to its maximum at a certain point in time, the temperature of the tubular material to be quenched does not instantly reach its maximum temperature. Rather, a certain temperature rise period is required, albeit an extremely short period. Therefore, the period until the temperature of the tubular material to be quenched reaches its maximum temperature within such a short period may also correspond to the second period described above. Similarly, the rate at which the heat treatment intensity (the strength of the current applied to the heating coil) is decreased during the third period can also be set appropriately depending on, for example, the length of the gradual change region to be provided in the tubular material to be quenched and the transport speed of the tubular material to be quenched. Furthermore, even if the strength of the heat treatment (the strength of the current passing through the heating coil) is changed from maximum to zero at a certain point in time, the temperature of the quenched portion of the tubular material does not instantly reach the ambient temperature, but rather requires a certain cooling period, albeit an extremely short period. Therefore, the period during which the temperature of the tubular material falls from the maximum temperature to the ambient temperature in such a short period may also correspond to the third period mentioned above.

[0052] By providing the second and / or third periods as described above, a region where the intensity of the heat treatment gradually changes can be provided between the heat-treated and non-heat-treated regions of the pipe material, which reduces the risk of problems such as crushing and / or breaking of the pipe material caused by stress concentration at the boundary between the quenched and non-quenched regions of the pipe material, for example, when excessive stress acts on the pipe material.

[0053] (Third embodiment) Depending on the mechanical properties required for the quenched portion of the tubular material to be quenched, it may be preferable to perform quenching by rapid cooling immediately after heating by the heating coil, for example, in order to increase the hardness of the tubular material to be quenched.

[0054] Therefore, in the pipe material quenching device according to the third embodiment of the present invention, the pipe material to be quenched that has been subjected to heating treatment by the heating coil section is cooled by a cooling section provided in the downstream conveying path downstream of the heating coil section.

[0055] The configuration of the cooling unit is not particularly limited as long as it is capable of cooling the tubular material to be quenched that has been subjected to heat treatment by the heating coil unit. For example, the cooling unit may be configured to spray a liquid such as water or oil or a gas such as air as a coolant onto the tubular material to be quenched that has been subjected to heat treatment by the heating coil unit.

[0056] The quenching apparatus 1 illustrated in Fig. 1 is equipped with a cooling section 12 that rapidly cools the section 15 to be quenched (the surface quenching section) by spraying water immediately after the heating coil section 9. In other words, the quenching apparatus 1 illustrated in Fig. 1 also satisfies the structural requirements of the quenching apparatus for pipe material according to the third embodiment of the present invention. The cooling section 12 is provided on the downstream conveying path 4 near the downstream side of the heating coil section 9. Such heating coil section 9 and cooling section 12 are also well known in continuous quenching apparatuses, so a detailed description thereof will be omitted.

[0057] Furthermore, for example, an additional cooling section may be disposed at a certain distance downstream of cooling section 12. By subjecting the portion to be quenched 15 to cooling, reheating, and recooling using multiple cooling sections disposed at predetermined distances, it is possible to perform quenching according to a desired cooling pattern and to improve the cooling capacity of the entire device. Furthermore, even if the distance between adjacent cooling sections exceeds the length of each individual tube material 5, intermediate rollers can be disposed between the adjacent cooling sections to prevent the tube material 5 from falling off the conveying path 2, thereby enabling smooth quenching and cooling processes.

[0058] Therefore, in a preferred third embodiment of the quenching apparatus for pipes according to the present invention, a plurality of cooling sections are provided in the downstream conveying path downstream of the heating coil section, and the quenching apparatus is configured to convey or support the heat-treated pipes to be quenched by a conveying mechanism or a support mechanism arranged between adjacent cooling sections.

[0059] FIG. 4 is a schematic diagram illustrating the configuration of the vicinity of a cooling unit included in a quenching apparatus for tubular materials according to a preferred third embodiment of the present invention. The quenching apparatus 1c illustrated in FIG. 4 includes multiple (two) cooling units 12 and 16 downstream of the heating coil unit 9 on the conveying path 2, and is configured to convey a quenched tubular material 5 (tubular material 6 to be quenched) by an intermediate roller 17a constituting a conveying mechanism (not shown) arranged between the cooling units 12 and 16. This prevents the tubular material 5 from falling off the conveying path 2, even though the distance between two adjacent cooling units 12 and 16 is longer than the length of the tubular material 5, allowing the quenching and cooling processes to be performed. Note that in the example illustrated in FIG. 4, the rotation axis of the intermediate roller 17a is perpendicular to the conveying direction of the tubular material 5. However, the configuration of the intermediate rollers included in the conveying mechanism or support mechanism arranged between adjacent cooling units is not limited to the above.

[0060] FIG. 5 is a schematic three-view diagram illustrating the configuration of a support mechanism disposed between multiple cooling sections included in a preferred third embodiment of the quenching apparatus for tube materials according to the present invention. More specifically, FIG. 5(a) is a plan view (top view) of the support mechanism 17, FIG. 5(b) is a side view of the support mechanism 17, and FIG. 5(c) is a front view of the support mechanism 17. The rotation axis of the intermediate roller 17b constituting the support mechanism 17 illustrated in FIG. 5 is parallel to the conveying direction of the tube material 5. This allows the tube material 5 supported by the support mechanism 17 to rotate around its central axis while being conveyed on the conveying path. However, the configuration of the conveying mechanism or support mechanism disposed between multiple cooling sections included in the preferred third embodiment of the quenching apparatus for tube materials according to the present invention is not particularly limited as long as it is possible to perform the quenching process and cooling process using the quenching apparatus according to the present invention while preventing the tube material from falling off the conveying path using the intermediate rollers arranged between adjacent cooling sections.

[0061] For the purpose of explaining the present invention, several embodiments having specific configurations have been described above, sometimes with reference to the accompanying drawings. However, the scope of the present invention should not be construed as being limited to these exemplary embodiments, and it goes without saying that appropriate modifications can be made within the scope of the claims and the matters described in the specification. [Explanation of symbols]

[0062] 1,1c Quenching equipment 2 Transport path 3 Upstream transport path 4 Downstream transport path 5 Tube material 6 Quenched tube material 7 First upstream pipe material 8 2nd upstream pipe material 9 Heating coil section 10 Speed ​​detection means 11 Displacement detection means 12 Cooling section 13 Laura 14 Step 15 Part to be hardened 16 Further cooling section 17 Support mechanism 17a, 17b Intermediate roller α distance β Length of the hardened area R1 Hardened area R2 Unhardened area R3 Gradually changing region R4: The area between area R1 and the edge (the area that is crushed)

Claims

1. A method for quenching a pipe material, comprising: conveying a plurality of pipe materials, each having its end portion abutting against another, on a conveying path at a predetermined speed; passing one of the plurality of pipe materials, a pipe material to be quenched, through a heating coil section installed on the conveying path; energizing the heating coil section only for a first period, which is a predetermined period from a first point in time, which is a predetermined timing; and performing a heat treatment on a first region, which is a predetermined region, of the pipe material to be quenched, The upstream end of a first group of pipe materials, which is a group consisting of a plurality of pipe materials that are in contact with each other approximately coaxially on the upstream side of the pipe material to be quenched, and the downstream end of a second group of pipe materials, which is a group consisting of a plurality of pipe materials that are in contact with each other approximately coaxially on the upstream side of the first group of pipe materials, are conveyed in an eccentric abutting state, speed information that is information correlated with the conveying speed of the first pipe material group and / or the second pipe material group is detected by a speed detection means; a displacement detection means for detecting a step portion caused by the eccentric state between the first group of pipes and the second group of pipes; calculating the first time point and the first period based on the speed information obtained by the speed detection means, a second time point which is the timing when the step portion is detected by the displacement detection means, and a first distance which is the distance between the heating coil portion and the displacement detection means in the conveying direction of the pipe material, and performing a heat treatment on the first region of the pipe material to be quenched; A method for quenching a pipe material.

2. 2. The method for quenching a pipe material according to claim 1, the conveying path includes an upstream conveying path and a downstream conveying path offset downward in a vertical direction relative to the upstream conveying path, When the most downstream pipe material among the plurality of pipe materials constituting the second pipe material group being transported on the upstream transport path falls onto the downstream transport path, the pipe material separates from the second pipe material group and joins the first pipe material group, and the step portion is formed at the abutment portion between the upstream end of the first pipe material group and the downstream end of the second pipe material group. A method for quenching a pipe material.

3. The method for quenching a pipe material according to claim 1 or 2, a second period during which the strength of the heat treatment applied to the tubular material to be quenched by the heating coil section is increased at a predetermined rate over a predetermined period immediately before the start of the first period, and / or a third period during which the strength of the heat treatment applied to the tubular material to be quenched by the heating coil section is decreased at a predetermined rate over a predetermined period immediately after the end of the first period; A method for quenching a pipe material.

4. 4. The method for quenching a pipe material according to claim 3, During the second period, the intensity of current supplied to the heating coil is increased at a predetermined rate, During the third period, the intensity of current supplied to the heating coil portion is reduced at a predetermined rate. A method for quenching a pipe material.

5. The method for quenching a pipe material according to claim 1 or 2, The pipe material to be quenched that has been subjected to the heat treatment is cooled by a cooling section provided in the conveying path downstream of the heating coil section. A method for quenching a pipe material.

6. 6. A method for quenching a pipe material according to claim 5, comprising: a plurality of the cooling units are provided in the conveying path downstream of the heating coil unit, The pipe material to be quenched that has been subjected to the heat treatment is transported or supported by a transport mechanism or a support mechanism arranged between adjacent cooling sections. A method for quenching a pipe material.

7. A quenching device for a pipe material, which conveys a plurality of pipe materials with their ends abutting each other on a conveying path at a predetermined speed, and when one of the plurality of pipe materials, a pipe material to be quenched, passes through a heating coil section installed on the conveying path, current is applied to the heating coil section only for a first period which is a predetermined period from a first point in time which is a predetermined timing, thereby performing a heat treatment on a first region which is a predetermined region of the pipe material to be quenched, a conveying path for conveying the upstream end of a first group of pipe materials, which is a group consisting of a plurality of pipe materials that are in contact with each other in a generally coaxial manner on the upstream side of the pipe material to be quenched, and the downstream end of a second group of pipe materials, which is a group consisting of a plurality of pipe materials that are in contact with each other in a generally coaxial manner on the upstream side of the first group of pipe materials, while the two groups are in contact with each other in an eccentric state; a speed detection means for detecting speed information that is information correlated with the conveying speed of the first pipe material group and / or the second pipe material group; a displacement detection means for detecting a step portion caused by the eccentricity between the first group of pipes and the second group of pipes; and a calculation means for calculating the first time point and the first period based on the speed information obtained by the speed detection means, a second time point which is the timing when the step portion is detected by the displacement detection means, and a first distance which is the distance between the heating coil portion and the displacement detection means in the conveying direction of the tubular material; Equipped with A quenching device for pipe material characterized by:

8. The quenching device for a pipe material according to claim 7, the conveying path includes an upstream conveying path and a downstream conveying path offset downward in a vertical direction relative to the upstream conveying path, By transporting the second group of pipe materials on the upstream conveying path and transporting the pipe materials to be quenched and the first group of pipe materials abutting the upstream side of the pipe materials to be quenched on the downstream conveying path, the pipe material located most downstream among the multiple pipe materials constituting the second group of pipe materials falls onto the downstream conveying path, causing the pipe material to detach from the second group of pipe materials and join the first group of pipe materials, and forming the step portion at the abutment portion between the upstream end of the first group of pipe materials and the downstream end of the second group of pipe materials. A quenching device for a pipe material, characterized in that it is configured as follows.

9. The quenching device for a pipe material according to claim 7 or 8, a second period during which the strength of the heat treatment applied to the tubular material to be quenched by the heating coil section is increased at a predetermined rate over a predetermined period immediately before the start of the first period, and / or a third period during which the strength of the heat treatment applied to the tubular material to be quenched by the heating coil section is decreased at a predetermined rate over a predetermined period immediately after the end of the first period; A quenching device for a pipe material, characterized in that it is configured as follows.

10. 10. The quenching apparatus for a pipe material according to claim 9, During the second period, the intensity of current supplied to the heating coil is increased at a predetermined rate, During the third period, the intensity of current supplied to the heating coil portion is reduced at a predetermined rate. A quenching device for a pipe material, characterized in that it is configured as follows.

11. The quenching device for a pipe material according to claim 7 or 8, a cooling unit provided in the conveying path downstream of the heating coil unit, The pipe material to be quenched that has been subjected to the heat treatment is cooled by the cooling unit. A quenching device for a pipe material, characterized in that it is configured as follows.

12. The quenching apparatus for a pipe material according to claim 11, a plurality of the cooling units are provided in the conveying path downstream of the heating coil unit, The pipe material to be quenched that has been subjected to the heat treatment is transported or supported by a transport mechanism or a support mechanism arranged between adjacent cooling sections. A quenching device for a pipe material, characterized in that it is configured as follows.

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