KR102080553B1 - Multi-stack heating apparatus for hot stamping - Google Patents

Abstract

Introduced is a multi-stage heating apparatus for hot stamping, which is a multi-layer stacking arrangement of a plurality of heating chambers partitioned from each other in a housing. A blank placed on a support is transferred from an inlet side to an outlet side by rotary motion of a work beam by the rotary motion of a rotary bar rotating in a circle around a rotary axis in the width direction. On each upper surface of the work beam and the support, projections arranged at intervals along the longitudinal direction are provided. The service lives of the work beam and the support are excellent.

Description

Multi-stage heating device for hot stamping {MULTI-STACK HEATING APPARATUS FOR HOT STAMPING}

The present invention relates to a hot stamping heating device for producing a high-strength component, in particular a multi-stage heating device for hot stamping in which a plurality of furnaces or heating chambers are stacked in a vertical direction.

The demand for weight reduction and high strength of vehicle parts is very high due to the regulation of fuel efficiency and the strengthening of safety regulations. As a result, ultra-high strength steel parts of 1 Giga Pascal (GPa) grade have been commercialized, and recently, the development of 2 Giga-grade steel has been promoted.

In general, as the strength of the steel sheet increases, the elongation is lowered, resulting in poor workability. Hot stamping has been proposed to solve this problem. Hot stamping is excellent in workability since the steel sheet is heated at or above the austenitization temperature, for example, 900 ° C. or higher, and then quenched simultaneously with press molding.

Since hot stamping is performed at a high temperature, oxidation of the steel sheet surface is inevitable, and descaling of the molded article surface is necessary after molding. Proposed to omit the descaling has been the plated steel sheet. In US Pat. No. 6296805, an Al-plated steel sheet for hot stamping is introduced.

In the conventional hot stamping, an electric furnace for heating while continuously transferring a steel sheet has been mainly used. These furnaces require large space, slow process speeds and high maintenance costs. Korean Patent No. 1045839 introduces a hybrid heating furnace combining high frequency induction heating with an electric furnace.

The hybrid furnace ensures a shorter process time, a smaller facility space, and a lower maintenance cost than a conventional electric furnace. But hybrid furnaces also have limitations. Despite significant process improvements and cost savings, the length of electric furnaces used as secondary furnaces is still long and there is still a need for cost reduction.

In addition to the continuous furnace described above, there are batch furnaces. The batch type occupies a smaller space than the continuous type, and is superior to the continuous type in terms of manufacturing cost and maintenance cost. However, even in a batch type having a multi-stage heating chamber, only one steel sheet is put into one heating chamber and the productivity is lowered since it is to wait until the heating is completed.

The present invention is based on the recognition of the prior art as described above, it is to provide a heating device for hot stamping that is excellent in productivity and cost-effective.

The problem to be solved in the present invention is not necessarily limited to the above-mentioned matters, and other problems not mentioned above may be understood by the matters described below.

The heating device for hot stamping according to the present invention for achieving the above object has a structure in which a heating chamber partitioned from each other in a housing is stacked in multiple stages. The heating chamber includes a heater; A door provided at an inlet of one end in the longitudinal direction and an outlet of the other end; A support extending in the longitudinal direction and arranged spaced apart in the width direction; And a work beam extending in the longitudinal direction and alternately arranged with the support in the width direction.

According to the present invention, the work beam is connected to the rotation bar arranged in the width direction, the rotation bar rotates in a circle around the axis of rotation in the width direction, the ground rod by the rotational behavior of the work beam by the rotational movement of the rotation bar Blanks placed on the can be transferred from the inlet side to the outlet side. The workbeam may be placed above the support at the top dead center of the rotational behavior and below the support at the bottom dead center.

According to the present invention, projections spaced apart in the longitudinal direction may be provided on the upper surface of the work beam. The upper surface of the support may be provided with projections spaced apart along the longitudinal direction. Furthermore, protrusions arranged along the longitudinal direction may be provided on the bottom surface of the work beam and / or the bottom surface of the support.

According to the present invention, the work beam and the support may be hollow as the longitudinal elongated shape.

According to the invention the work beam is connected to the rotating bar via a bracket, the bracket is a base fixed to the rotating bar; Legs extending from the base to be in close contact with the left and right sides of the work beam; And a support connecting the legs so that the lower surface of the work beam is supported. The work beam may be tightened and secured between the legs by a first fastener penetrating the leg and the work beam. In addition, the base is fixed to the rotation bar by the second fastener, it may be configured so that the fixed height of the bracket can be adjusted by the operation of the second fastener.

In addition, according to the present invention, the heating chamber is partitioned by the heat-resistant beam, the heat-resistant beam is extended in the longitudinal direction and both ends are fixed to the housing and arranged in close contact in the width direction may constitute the bottom of the heating chamber.

In addition, according to the present invention, both ends of the support may be fixed to the support blocks provided on the inlet and outlet sides of the heating chamber, respectively. The support block has a mounting groove into which the support is fitted and a groove through which the work beam passes, and the groove is formed deeper and wider than the mounting groove, and the support block can insert a fork from the outside against the corresponding portion of the other supporting block. A horizontal extension is provided for forming the opening, and the door can be provided to open and close the opening.

The multi-stage heating apparatus for hot stamping according to the present invention as described above is configured in a batch type, so that the occupied space is small, and manufacturing cost and maintenance cost can be reduced.

In addition, the multi-stage heating apparatus for hot stamping according to the present invention is excellent in productivity because it is heated while transferring the blank injected at the inlet side of the heating chamber to the outlet side. In the heating chamber, the blank is conveyed by repeating the transfer and stop by the rotating work beam. Feeding and stopping of the blank may be adjusted in consideration of the target heating temperature and the length of the heating chamber.

In addition, according to the present invention, the lifespan of the work beam and the support is long, the heat loss from the heating chamber is low, and the repair and correction are easy.

Figure 1 shows an example of a multi-stage heating device for hot stamping.
FIG. 2 shows a blank conveying method of the heating apparatus shown in FIG. 1.
3 and 4 show damaged work beams and supports, respectively, after being used in the heating apparatus shown in FIG.
5 shows a multi-stage heating device for hot stamping according to an embodiment.
6 shows the inlet side of the heating device shown in FIG. 5.
Figure 7 shows a work beam, a rotating bar and a bracket for coupling them according to the embodiment.
8 shows a bottom of a heating chamber according to an embodiment.
9 shows a support and a work beam installed in a heating chamber according to an embodiment.
10 shows a support block according to an embodiment.
11 is a schematic view showing the structure of a projection according to the embodiment.
12 shows a support formed with a protrusion according to the embodiment.

Hereinafter, examples will be described in more detail so that various aspects of the present invention can be understood. In the accompanying drawings, the same or equivalent components or parts are denoted by the same reference numerals as much as possible for the convenience of description, and the drawings may be exaggerated and schematically illustrated for a clear understanding and explanation of the features of the present invention. have.

In the description of the present invention, unless otherwise defined, the fact that the second element is disposed on the first element 'on' or that the two elements are 'connected' to each other means that the two elements are in direct contact with each other as well as the first and the first. It is necessary to understand the meaning of allowing a third element to be interposed between the elements of two elements. Directional expressions such as front and rear, left and right or up and down are for convenience of explanation.

1 shows a multi-stage heating device for hot stamping in which a batch type and a continuous type are mixed. In FIG. 1, the length direction corresponding to the blank conveying direction is indicated by L, and the left and right width directions are indicated by W. In FIG.

Referring to FIG. 1, the heating apparatus has a structure in which the heating chambers 10 partitioned from each other in the housing 100 are stacked and stacked in multiple stages.

On the bottom side of the heating chamber 10, the support base 20 and the work beam 30 extending in the longitudinal direction are alternately arranged in the width direction, and the heaters 40 extending in the width direction on the ceiling side are spaced apart along the length direction. do. The blank put into the heating chamber 10 at the inlet side is transferred to the outlet side by the work beam 30.

Rotating bars 50 extending in the width direction are provided at the inlet and outlet sides of the heating chamber 10, respectively. One end of the work beam 30 is connected to the rotation bar 50 on the inlet side and the other end is connected to the rotation bar 50 on the outlet side. Each rotation bar 50 rotates in a circle around a rotation axis in the width direction, and the work beam 30 is rotated by the rotation bar 50.

On the inlet side of the heating device is provided an electric motor 110 for the rotational movement of the rotary bar (50). The driving force of the electric motor 110 may be transmitted to the rotating bar 50 through the gear box 120 and the rotating body (not shown). Rotation of the rotation bar 50 may be in various ways. As an example, the rotational movement of the rotation bar 50 may be due to the crank shaft which is electrically driven.

Rotating bar 50 of the outlet side is simply driven by the rotational movement of the inlet side rotating bar 50, or can be actively rotated by the electric motor 110, such as the inlet side rotating bar (50).

2 illustrates the rotational motion of the work beam 30 and the blank conveying process in this order.

As shown in FIG. 2, the work beam 30 connected to the rotation bar 50 arranged in the width direction shows a rotational motion similarly drawing a circle by the rotation movement of the rotation bar 50. The driving force of the electric motor 110 is transmitted to the rotating body 130 through the gear box 120, the rotational movement of the rotating body 130 is transmitted to the work beam 30 eccentrically connected to the rotating body 130.

2 (a) shows a state in which the work beam 30 is placed at the bottom dead center of the rotational behavior, and at the bottom dead center, the work beam 30 is placed below the support 20. The blank 1 introduced into the inlet side of the heating chamber 10 is mounted on the support 20.

2 (b) shows a state in which the work beam 30 is rotated and placed at the top dead center by the driving force of the electric motor 110, and the work beam 30 is placed above the support at the top dead center. In the process from the bottom dead center to the top dead center, the blank 1 placed on the support 20 is moved to the work beam 30 and moved.

As shown in (c) and (d) of FIG. 2, the blank 1 placed on the work beam 30 is transferred to the exit side in the process of reaching the top dead center again to the bottom dead center, and the blank placed on the work beam 30 is moved. (1) is moved back to the support (20).

As can be seen in FIG. 2, in the heating chamber 10, the blank 1 is conveyed while repeating the transfer and stop by the work beam 30 which rotates. The electric motor 110 operates at predetermined intervals to rotate the work beam 30. By adjusting the rotation trajectory size, rotation speed, and period (or rotation interval) of the work beam 30, the residence time or average transfer speed of the blank 1 in the heating chamber 10 may be adjusted.

The multi-stage heating device as described above can shorten the length of the heating chamber 10, that is, the length of the heating device, and can be heated as in a continuous furnace by putting a plurality of blanks in the heating chamber 10. This saves installation and maintenance costs as well as significant productivity.

Despite these many advantages, the multi-stage heating device has several problems and needs to be improved.

3A shows a damaged work beam 30 after being used in the multistage heating apparatus shown in FIG. 1.

Al-plated steel sheet is mainly used as a hot stamping blank. The heating apparatus is controlled to form an oxide film before Al plating is melted in the heating chamber 10. However, a part of Al plating is melted and buried in the work beam 30, and as the process continues, the dye transfer of Al plating accumulates and diffusion into the work beam 30 proceeds. Al plating penetrates into the work beam 30 of a ceramic material and forms the hard structure A with high hardness (refer FIG. 3B).

As shown in FIG. 3A, the hard tissue A due to diffusion of the Al plating is formed in a wavy pattern, and cracks are mainly generated in the boundary region A2 between the regions A1 deeply penetrated by the Al plating. In the process of thermal expansion and contraction of the work beam 30 due to the interruption of operation and resumption, it is thought that a crack occurs due to the difference between the region A1 where the hardening proceeds a lot and the region A2 that is relatively soft. These cracks and breaks lead to a very short lifespan of the work beam 30 and to frequent shutdowns.

4 shows the support 20 damaged after being used in the multi-stage heating device shown in FIG.

The support 20 is formed in a U-shape in which the bottom is wide and the blank support is vertically extended. The support 20 is made of ceramic similar to the work beam 30, but has a longer life than the work beam 30, but is damaged due to the hard structure due to the penetration of self-weight and Al plating.

FIG. 5 shows the front, ie, inlet, side of a multistage heating apparatus for hot stamping according to an embodiment. Parts not specifically described below may be understood to be similar to the multi-stage heating apparatus described above, and reference numerals are used as they are.

As shown in FIG. 5, the multi-stage heating apparatus has a structure in which seven heating chambers 10 partitioned from each other in the housing 100 are stacked and arranged. The inlet of the heating chamber 10 is provided with a fork entry port 11 for introducing a blank. The fork is mounted on the robot arm and the blank is placed thereon and transported into the heating chamber 10.

FIG. 6 is an enlarged view of a part of the front surface of the heating apparatus shown in FIG. 5. The inlet of the first chamber 10a is closed by the door 140 and the inlets of the second and third chambers 10b and 10c are open.

Referring to FIG. 6, the work beams 30 are spaced apart in the width direction of the heating chamber 10, and although not shown, a support 20 is disposed between the work beams 30 and the work beams 30 adjacent thereto. Is placed. The inlet of the heating chamber 10 is provided with a fork inlet 11 in the longitudinal direction, the door 140 provided on the inlet side opens and closes the fork inlet 11. The door 140 is opened to insert the blank, and the inlet of the heating chamber 10 is closed by the door 140 after the blank is inserted. The opening and closing operation of the door 140 is by the rotation operation of the rod 141 extending in the width direction.

FIG. 7 shows the work beam 30 fixed to the rotation bar 50 using the bracket 60.

The work beam 30 is formed in an elongated shape in the longitudinal direction when viewed in cross section, and is hollow in its lengthwise direction. By way of example, the workbeam 30 may be understood as a hollow pipe having a rectangular cross section with rounded corners. This work beam 30 is lightweight and lowers the possibility of cracking or breaking due to thermal expansion shrinkage.

The bracket 60 includes a base 61 fixed to the rotation bar 50, legs 62 extending from the base 61 so that the left and right sides of the work beam 30 come into close contact with each other, and a bottom surface of the work beam 30. It is provided with a support 63 for horizontally connecting the legs 62 so as to be supported.

The work beam 30 is tightened and fixed between the legs 62 by the first fastener 64 penetrating the leg 62 and the work beam 30 in the horizontal direction. The base 61 is fixed to the rotation bar 50 by the second fastener 65. As the second fastener 65, a tannery bolt may be used to easily adjust the height of the bracket 60, that is, the height of the work beam 30.

8 is a view showing that the heat-resistant beams 70 constituting the bottom of the heating chamber 10 are closely arranged in the width direction.

Since the temperature in the heating chamber 10 is very high, above 900 ° C., no steel plate can be installed to partition between neighboring heating chambers. On the other hand, if the neighboring heating chambers are not partitioned with each other, temperature control and maintenance in the heating chamber 10 are difficult.

The partition between neighboring heating chambers 10 is made using the heat-resistant beam 70 of ceramic material. The heat-resistant beam 70 extends in the longitudinal direction and both ends thereof are fixed to the housing 100. It would be nice if there was a member for supporting it in the middle of the longitudinal direction of the heat-resistant beam 70, but the support member in the middle is limited due to the high temperature environment in the heating chamber 10. At high temperatures, the heat resistant beams 70 are broken by their own weight. The broken heat-resistant beam 70 can be replaced with a new one relatively simply, and can be used upside down if the breakage is not severe.

As shown in Figure 8 and 9, the support block 80 is arranged in close contact in the width direction on the bottom of the heating chamber 10 of the inlet and outlet side. Both ends of the support 20 are fitted to the support block 80 at the inlet and outlet sides thereof. The support block 80 facilitates replacement or repair as well as installation of the support 20. Support 20 is only fixed to both ends mounted to the support block (80). In the middle of the support 20 or the work beam 30, a member for supporting them is not provided.

10 shows an example of a support block 80 according to an embodiment.

9 and 10, the support block 80 includes a mounting groove 81 into which the support 20 is fitted and a recess 82 through which the work beam 30 passes. The recess 82 is deeper and wider than the mounting recess 81 to allow the rotational movement of the work beam 30. The support block 80 is provided with a horizontal extension 83 for forming an entry port 11 through which the fork can enter from the outside against the corresponding portion of the other support block.

11 schematically shows a projection 31 formed in the work beam 30 to prevent cracking due to the penetration of Al plating.

9 and 11, the projections 31 are spaced apart from each other along the longitudinal direction on the upper surface of the work beam 30 to which the blank 1 is in contact. Projection 31 is preferably formed in a width (or longitudinal thickness) of 2.0 ~ 3.0mm, the height of 2.0 ~ 3.0mm. And it is preferably formed at intervals of 80.00mm. When the protrusions 31 are formed in this way, the lifespan of the work beams 30 is increased by an average of 2 times or more.

A width of less than 2.0 mm or more than 3.0 mm in height of the protrusions 31 causes machining difficulties and does not guarantee an effect beyond that which can be obtained from 2.0 to 3.0 mm. If the projections 31 have a width of more than 3.0 mm or less than a height of 2.0 mm, the amount of dye transfer and penetration depth of the Al plating tends to increase or the variability of the obtained state increases. The distance between the projections 31 needs to be adjusted according to the shape or size of the blank, but an interval of about 80.00 mm is preferable based on the blank being generally applied.

The protrusion 31 may be formed on the lower surface as well as the upper surface of the work beam 30. After the upper surface of the work beam 30 is used to support the blank, if there is no problem of cracking or breaking yet, it can be used in a way that the lower surface to support the blank, it helps to extend the life of the work beam 30 do.

12 shows a support 20 fitted to the support block 80.

9 and 12, the projections 21 are spaced apart along the longitudinal direction on the upper surface of the support 20 to which the blank 1 is in contact. The protrusion 21 is formed in the same numerical range as the protrusion 31 of the work beam 30. The projection 31 may be formed on the lower surface as well as the upper surface of the support 20, and may be used upside down after a certain period to extend the life.

Support 20 is the same as the work beam 30, when viewed in cross-section longitudinally elongated shape may be formed in a hollow hollow in the longitudinal direction. This support 20 is lightweight and lowers the possibility of cracks or breakage due to thermal expansion shrinkage.

While specific embodiments of the present invention have been shown and described, it should be understood that the present invention may be variously modified or modified without departing from the spirit of the invention as set forth in the claims below.

In addition, the reference numerals described in the following claims are not limited to this, but are described in order to more easily understand the configuration of the present invention through the embodiments shown in the drawings.

10: heating chamber 11: fork entrance
20: support 21, 31: protrusion
30: work beam 40: heater
50: rotating bar 60: bracket
70: heat-resistant beam 80: support block
100: housing 110: motor

Claims (5)

The heating chambers partitioned from each other in the housing are stacked in multiple stages,
The heating chamber includes a heater; A door provided at an inlet of one end in the longitudinal direction and an outlet of the other end; A support extending in the longitudinal direction and arranged spaced apart in the width direction; And a work beam extending in the longitudinal direction and alternately arranged with the support in the width direction,
The work beam is connected to a rotation bar arranged in the width direction, and the rotation bar rotates in a circle around the rotation axis in the width direction, and the blank is placed on the substrate by the rotational behavior of the work beam by the rotational movement of the rotation bar. Is transported from the inlet side to the outlet side, the work beam lies above the support at the top dead center of rotational behavior and below the support at the bottom dead center,
The workbeam is connected to the rotating bar via a bracket,
The bracket is a base fixed to the rotating bar; Legs extending from the base to be in close contact with the left and right sides of the work beam; And a support for connecting the legs to support the lower surface of the work beam,
The work beam is tightened and fixed between the legs by a first fastener penetrating the leg and the work beam,
The base is fixed to the rotation bar by a second fastener, the multi-stage heating device for hot stamping, characterized in that the fixing height of the bracket can be adjusted by the operation of the second fastener. The multistage heating apparatus for hot stamping according to claim 1, wherein the work beam and the support are hollow in a longitudinal shape. The method according to claim 1, wherein the projections are arranged spaced apart in the longitudinal direction on the upper surface of at least one of the work beam and the support, the projections are characterized in that the width is formed 2.0 to 3.0mm, height 2.0 to 3.0mm Multi-stage heating device for stamping. delete The method of claim 1, wherein the heating chamber is partitioned by a heat-resistant beam, the heat-resistant beam extends in the longitudinal direction, both ends are fixed to the housing and arranged in close contact in the width direction to constitute the bottom of the heating chamber,
Both ends of the support are fixed to the support blocks provided at the inlet and outlet sides of the heating chamber,
The support block has a mounting groove into which the support is fitted and a groove through which the work beam passes. The groove is formed deeper and wider than the mounting groove. And a horizontal extension for forming the opening, wherein the door is provided to open and close the opening.

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