JP2006212690A - Method and apparatus for hot press forming of metal sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot press forming method and an apparatus therefor, which can rationally solve the problems that unevenness of temperature is generated in the metal sheet during transferring it and a succeeding forming work becomes difficult due to an excessive increase of quench hardness, and can also set up a quench hardness of each part of a press formed product at any level. <P>SOLUTION: The hot press forming method includes the steps of: transferring the metal sheet heated in a heating device to a metal die constituting the press forming apparatus, by a transfer mechanism equipped with a hand portion to hold the sheet; and press-forming the metal sheet using the metal die. The hot press forming method is characterized in that the metal sheet is held and transferred so as to have designated positions of the metal sheet contacted with the hand portion, and after temperature of the positions contacting with the hand portion becomes different from that of the other positions through contact heat removal, the press forming is started. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

In this invention, a metal plate heated by a heating device such as a heating furnace is transported to a mold constituting a press molding device by a transport device having a hand portion for holding the hot plate, and is hot-molded using the mold. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press forming method and an apparatus therefor, and more particularly to a hot press forming method and an apparatus for a metal plate capable of arbitrarily setting the quenching hardness of each part of a press formed product.
Furthermore, the metal plate material heated by a heating device such as a heating furnace is transported to a cooling device such as a cooling tank by a transport device including a hand unit that holds the metal plate, and is cooled by a predetermined cooling means in the cooling device, BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method and apparatus for a metal plate material for obtaining a quenched metal plate material, and more particularly to a heat treatment method and apparatus for a metal plate material that can arbitrarily set the quenching hardness of each part of the metal plate material.

Metal sheet press molding is highly productive, excellent in dimensional accuracy, and stable in quality with little variation in strength between pressed products, making it suitable for manufacturing automobiles, machinery, electrical equipment, transportation equipment, etc. It is the most common processing method widely used.
However, press products in recent years, especially automobile parts, are required to have high strength from the viewpoint of weight reduction, etc., and this leads to a decrease in formability, particularly a decrease in shape freezing due to the occurrence of a springback, It has become difficult to manufacture a press product having a complicated shape.

For this reason, in the press industry of a metal plate material, the hot press molding method which shape | molds the heated metal plate material attracts attention. The hot press molding method press-molds a metal plate heated to a high temperature, so the metal plate with reduced material strength is deformed straight along the molding surface of the mold and is excellent even in complicated shapes It can be molded with dimensional accuracy. In addition, since the mold is rapidly cooled by the heat removal effect of the die after the press molding, no springback is generated, the shape freezing property is excellent, and the dimensional accuracy of the press product can be improved. Further, when the metal plate material is steel, the steel plate is heated to the austenite region, and this is held in a mold and rapidly cooled to achieve high strength by martensitic transformation. In other words, the hot press forming method can be said to be a press forming method that can achieve both high strength and excellent dimensional accuracy that cannot be realized by the conventional cold press forming method.
JP 2002-248525 A JP 2003-328031 A

Conventionally, when performing hot pressing, a metal plate material to be molded is heated to a high temperature and uniformity with a heating device such as a heating furnace, and the utmost care is taken to prevent temperature drop and temperature unevenness. Generally, it is conveyed to a press molding apparatus while paying.
However, although it is transported with great care, the metal plate heated to a high temperature and the transport device at the time of transport come into contact with each other at a predetermined site, for example, the hand portion that is a holding means of the transport device. Then, heat removal due to contact occurs, and temperature unevenness occurs in the metal plate material. Accordingly, it is inevitable that temperature unevenness occurs in the metal plate material unless a special device is devised in the transport device or the transport method.
For this reason, a method has been proposed in which the metal plate material is heated inside the mold in order to prevent the temperature unevenness of the metal plate material due to the conveyance, and consequently the uneven hardness of the press-molded product due to the temperature unevenness. For example, a method of attaching a plurality of electrodes to a metal plate material set between a punch and a die, supplying electric power between opposing electrodes to generate Joule heat, and hot-pressing the metal plate material uniformly heated by this method Is disclosed (for example, see Patent Document 1).
However, this method can solve the problem of uneven temperature in the metal plate during transportation, but each time it is set in the mold, multiple electrodes must be attached to the metal plate, and the Joule heat Because of heating, productivity is significantly reduced. Therefore, there is a considerable practical problem in applying the method to press forming of a metal plate material that requires productivity.

Furthermore, a hot press forming method capable of achieving high strength by martensitic transformation by heating the metal plate material to the austenite region, holding it in the mold and cooling it by the contact heat removal effect However, there is a problem that the quenching hardness increases so much that post-processing such as drilling (piercing) or cutting (trim) becomes difficult.
For this reason, a method is disclosed in which the contact area of the mold forming surface and the mold temperature are made different for each molding part, the quenching hardness of the part requiring post-processing is reduced, and the processing of the part is facilitated. (For example, refer to Patent Document 2).
However, according to this method, post-processing becomes easy. However, as described above, when unevenness in temperature occurs in the metal plate due to conveyance, not only the part that requires post-processing but also the part that requires strength. There is a possibility that the quenching hardness will also decrease.

Note that the characteristics required for automobile parts and the like are not limited to lightening and increasing strength as described above. For example, in recent years, the body of automobiles has become more demanding of product design and collision safety, so the thickness and strength of each part of the body are detailed in order to achieve the performance. The number of parts constituting the body has reached several hundred.
For this reason, press materials, that is, tailored blanks in which a plurality of metal plate materials having different plate thicknesses and strengths are joined and integrated, are widely used in recent automobile parts and the like. Tailored blanks have an excellent feature that the characteristics of one metal plate can be partially changed according to the purpose. For example, a high-strength steel plate is applied only to parts where strength is required. While maintaining the necessary strength, it is possible to reduce the weight of the portion that does not require strength. In addition, for tailored blanks, a metal plate having a thickness and strength suitable for the purpose is selected, and this is integrated by welding, so the strength of each part of the press-formed product must be set accurately and arbitrarily according to the purpose. Is possible. For this reason, it is possible to manufacture a body excellent in collision safety while satisfying a design with a strong product, and to reduce the number of parts.

  However, although it is a tailored blank that contributes not only to reducing the weight and strength of the automobile body but also to improving design and collision safety, as described above, the metal plate materials are joined and integrated by welding, The production of tailored blanks requires advanced welding techniques. That is, unless an advanced welding technique is applied, breakage is likely to occur in the welded portion when press forming, and the superior characteristics of the tailored blank cannot be exhibited unless the strength of the welded portion can be ensured. Moreover, in the current situation where the strength of automobile parts is increasing, an increasingly advanced welding technique is required.

That is, as described above, the hot press forming method can be said to be a press forming method capable of achieving both high strength and excellent dimensional accuracy that could not be realized by the conventional cold press forming method. In today's environment, it is not only satisfying the above characteristics, but as a new technology to replace tailored blanks, the strength of each part of the press-molded product, especially the hot press molding can be set arbitrarily. Technology development is highly desired in industry.
In addition, as described above, the tailored blank has the effect of reducing the number of parts such as an automobile body because a metal plate material having a thickness and strength suitable for the purpose is selected and integrated by welding. However, if the metal plate heat treatment technology that can arbitrarily set the quenching hardness of each part of the metal plate material and the metal plate material having different quenching hardness depending on the part can be manufactured, the number of blanks constituting the tailored blank and welding The work time required for this can be greatly reduced and shortened.

The problem to be solved by the present invention is to solve the problem that temperature unevenness occurs in the metal plate material during conveyance and the problem that post-processing becomes difficult due to excessive increase in quenching hardness, and press-formed product. It is an object of the present invention to provide a hot press molding method and apparatus capable of arbitrarily setting the quenching hardness of each part.
Another problem to be solved by the present invention is that the metal plate material heated by a heating device such as a heating furnace is transported to a cooling device such as a cooling tank by a transport device including a hand unit that holds the metal plate material. Also in the heat treatment of the metal plate material to obtain a quenched metal plate material by cooling by inserting / immersing the metal plate material in the cooling tank, etc. The problem of uneven temperature in the metal plate material and the problem that post-processing becomes difficult due to excessive increase in the quenching hardness, so that the problem can be solved reasonably and quenching of each part of the metal plate material It is an object to provide a heat treatment method and apparatus for a metal plate, the hardness of which can be arbitrarily set.

Furthermore, in recent years, a hot press molding technique that can perform draw molding or foam molding with a severe curvature is newly desired. This is because, in cold press, the deformation resistance of the stretched part is improved by work hardening, but in hot press, the metal plate material is heated to a high temperature, so the deformation resistance of the metal plate material is low. It is. That is, with the recent increase in strength of press products, the conventional cold press forming technique has a problem that the shape freezing property is lowered, and this is a hot press forming method that is attracting attention to cope with this. In the hot press forming technology that heats a metal plate material to a high temperature, once the elongation accompanying the forming occurs, the cross-sectional area of the portion becomes small, so the strength of the portion where the plate thickness decreases due to the elongation becomes lower. Therefore, when performing press molding with intense material flow accompanying molding processing represented by deep drawing, local thinning and breakage occur in the stretched portion, so-called draw molding cannot be performed. There was a problem. Further, even in the foam molding in which the material flow accompanying the processing is not severe as compared with the deep drawing molding, there is a problem that the fracture occurs when the curvature is severe.
Therefore, yet another problem to be solved by the present invention is to provide a hot press molding method and apparatus capable of drawing molding and form molding with severe curvature, which could not be realized by the conventional hot press molding technology. That is.

  The present inventor firstly explained that the conventional heating method, that is, the method of heating a metal plate with a heating apparatus such as a heating furnace is the most suitable method for press forming of a metal plate that requires productivity. In order to rationally solve the problem that temperature unevenness occurs in the metal plate material during conveyance and the problem that post-processing becomes difficult due to excessive hardening hardness after press forming, The following findings were obtained as a result of theoretical and experimental studies.

(A) A temperature drop due to contact heat removal occurs in a portion of the metal plate material (hereinafter referred to as a contact portion) that comes into contact with the hand portion (metal plate holding means included in the transport device), and the temperature of other portions. Unlike the above, temperature unevenness occurs as described above. However, if the phenomenon that the temperature of the contact portion is lower than that of the surrounding portion is positively utilized, the quenching hardness increases too much without specially contriving the mold as in Patent Document 2. The latter problem that post-processing becomes difficult can be solved. That is, in the past, it was common to start press molding by transporting a heated metal plate material to a mold constituting the press molding apparatus or the press molding apparatus so as not to cause temperature unevenness as much as possible. The latter problem can be solved by changing the way of thinking and actively controlling the temperature of the metal plate at the transport stage.

(B) Specifically, a part subjected to machining after press molding, for example, a part that requires post-processing (piercing, trim, etc.) is held and conveyed so as to contact the hand part, Since the temperature of the part to be machined, that is, the contact part is lowered from the temperature of the other part by contact heat removal, this corresponds to lowering the quenching start temperature of the contact part. The thickness is lower than the quenching hardness of other parts, and machining after press molding becomes easy.
Furthermore, in order to solve the problem of post-processing by the conventional method, after the conveyance, for example, after setting the metal plate material in the mold, a process for partially changing the quenching hardness of the press-formed product Although a process is required, can the processing process for partially changing the quenching hardness of the press-molded product be omitted if the temperature control is positively performed on the metal plate material while transporting as described above? Processing time can be shortened and productivity can be improved.

(C) Further, if the hand part is constituted by a suction pad or a clamp, it becomes easy to bring the hand part into contact with a predetermined part of the metal plate material, for example, a part subjected to machining after press molding, or press molding. It becomes easy to contact the hand part only with a part that is later subjected to machining, and further, if the hand part is constituted by a suction pad or a clamp provided with either or both of a heating means and a cooling means, Since the temperature can be controlled by either one or both of contact heat removal or cooling by the cooling means and temperature rise by the heating means, the quenching start temperature of the contact site can be arbitrarily controlled. That is, as shown in (B), not only the quenching hardness of the press-formed product is different between the contact part and other parts, but also the quenching hardness of the contact part can be arbitrarily set.

  The above is the knowledge that the quenching hardness of the contact part can be controlled by positively controlling the quenching start temperature of the contact part in the conveying stage. After setting, it is possible to arbitrarily set the quenching hardness of each part of the press-molded product by controlling either one or both of the quenching start temperature and the cooling rate, and the holding time in the mold. We obtained the knowledge that productivity can be improved by shortening. Specifically, it is as follows.

(D) After setting the metal plate material in which the quenching start temperature of the contact part is controlled in the conveying stage to the mold, quenching of each part of the metal plate material by a predetermined cooling means in at least one state before molding, during molding and after molding If the starting temperature and cooling rate are controlled, the quenching hardness of each part of the press-formed product can be set arbitrarily.
(E) And, as the predetermined cooling means, cooling by refrigerant discharge from a plurality of refrigerant discharge ports provided on the mold surface is desirable from the viewpoint of productivity and controllability of quenching start temperature and cooling rate. Further, by sequentially recovering the refrigerant from the plurality of refrigerant recovery ports provided on the mold surface, the cooling efficiency and the controllability of the heat transfer coefficient by the refrigerant discharge are further improved.
(F) Furthermore, the refrigerant discharge is controlled for one or more parameters selected from the refrigerant discharge amount, the discharge flow rate, the discharge pressure, the discharge time, and the discharge timing, and for each refrigerant discharge port or If the refrigerant discharge from a plurality of refrigerant discharge ports is grouped and controlled independently for each group, the heat transfer coefficient of cooling by refrigerant discharge can be freely changed, and thereby the quenching hardness of each part of the molded product It is possible to control freely.

  This will be described below with reference to FIG. 1 schematically showing the principle of the present invention. FIG. 1 is an example of a CCT curve of carbon steel indicating that the structure of the steel sheet can be controlled by controlling the cooling start temperature and cooling rate of the steel sheet. For example, when the steel sheet is cooled from the cooling start temperature T1, if it is cooled according to the cooling curve 1, it passes through the outside of the nose (borderline of transformation), so that most of the steel material becomes martensite and a high strength structure is obtained. On the other hand, when cooled according to the cooling curve 2, ferrite and cementite are precipitated to pass through the inside of the nose, so that the martensite ratio in the steel material obtained after cooling is reduced, and a relatively low strength structure is obtained. Further, when cooling is performed in accordance with the cooling curve 3 having the same cooling rate as the cooling curve 2 with the cooling start temperature T2 lower than T1, ferrite and cementite are precipitated at a lower rate than in the cooling curve 2, and thus obtained after cooling. The ratio of martensite in the steel material is larger than that in the case of the cooling curve 2 and smaller than that in the case of the cooling curve 1, and a medium strength structure is obtained.

  That is, the present invention conforms to the CCT curve indicating that the structure of the steel sheet can be controlled by controlling the cooling start temperature and cooling rate of the steel sheet. Heat removal from the hand part, refrigerant discharge from a plurality of refrigerant discharge ports provided on the mold surface, or refrigerant discharge from a plurality of refrigerant discharge ports provided on the mold surface and refrigerant recovery from the refrigerant recovery port The quenching start temperature of each part of the metal plate material is controlled, and after the start of pressing, that is, either during or after molding, by one or both of refrigerant discharge from a plurality of refrigerant discharge ports provided on the mold surface. The essence is to arbitrarily control the quenching hardness of each part of the press-formed product by controlling the cooling rate of each part of the metal plate material. Then, by independently controlling the quenching start temperature and the cooling rate for any part of the metal plate material, it is possible to obtain press-molded articles having different mechanical properties in any part, that is, each part of the molded article It is essential to freely control the strength. Note that rapid cooling is not required as the refrigerant is used, the processing is not severe, and if sufficient cooling speed can be obtained by heat removal by contact with the mold, press molding processing may be performed without discharging the refrigerant. Needless to say.

  The above is the knowledge about the hot press forming method of the metal plate material, but the present inventor says that the metal plate material also has temperature unevenness during the conveyance in the heat treatment method of the metal plate material, similarly to the hot press forming method. In view of the problem and the problem that the hardened hardness is excessively increased and machining such as piercing and trim becomes difficult, the above method cannot be applied to the heat treatment method of the metal plate material having the same problem. The following findings were obtained.

(G) A metal plate material that is heated by a heating device and conveyed to a cooling device such as a cooling tank by a conveying device having a hand portion that holds the metal plate material, and is cooled by a predetermined cooling means in the cooling device and quenched. In this heat treatment method, if the metal plate material is held and transported so that a predetermined portion of the metal plate material, for example, a portion requiring post-processing (piercing, trim, etc.) is in contact with the hand portion, the post-processing is performed. This is equivalent to lowering the quenching start temperature of the contact part because the temperature of the required part, that is, the contact part is lower than the temperature of the other part by contact heat removal. It is lower than the quenching hardness of the part, and post-processing at the part becomes easy.
Furthermore, in order to solve the problem of post-processing by the conventional method, a processing step for partially changing the quenching hardness of the metal plate material after the conveyance is necessary. If the temperature control of the plate material is performed, the processing step can be omitted or the processing time can be shortened, and the productivity is improved.

(H) Moreover, when the hand part is constituted by a suction pad or a clamp, it becomes easy to bring the hand part into contact with a predetermined part of the metal plate material, for example, a part requiring post-processing such as piercing or trim, or It becomes easy to contact the hand only with a portion requiring post-processing such as piercing and trim, and the hand portion is constituted by a suction pad or a clamp having either one or both of heating means and cooling means. Then, since the temperature of a contact part can be controlled by either one or both of contact heat removal or cooling by a cooling means and temperature rise by a heating means, the quenching start temperature of the contact part can be arbitrarily controlled. That is, as shown in (G), not only the quenching hardness of the metal plate material is made different between the contact part and other parts, but also the quenching hardness of the contact part can be arbitrarily set.

Next, in order to prevent local thinning and breakage of a metal plate material as a molding material, the present inventor is responsible for the cause of breakage and thinning due to draw molding and severe form forming, and a method for solving this. As a result of many theoretical and experimental studies, the following findings were obtained.
(I) In cold pressing, the deformation resistance of the stretched part is improved by work hardening, but in hot pressing, the metal plate material is press-formed in a heated state, so the deformation resistance of the metal plate material is low. Once the elongation due to molding occurs, as shown in Fig. 12 (c), the cross-sectional area of the stretched portion becomes smaller, so the strength of the portion where the plate thickness decreases due to the elongation becomes even lower. In fact, breakage occurs. FIG. 12 (a) schematically shows a metal plate material that is a uniformly heated material, and FIG. 12 (b) schematically shows a press-formed product when cylindrical drawing is performed using the metal plate material.

(J) However, as shown in FIG. 12 (d), the temperature of a portion with a high degree of processing, for example, a portion where the plate thickness decreases due to elongation associated with draw molding or foam molding, is lowered in advance to increase the strength of the portion. If it is raised in advance, as shown in FIG. 12 (f), the other part having a lower strength than the part is extended, so that the load on the part with a high degree of processing can be reduced and the breakage can be prevented.
(K) Further, not only the temperature distribution in the form as shown in FIG. 12 (d) but also the temperature distribution in the form as shown in FIG. The above effect can also be obtained by forming a temperature distribution in which low-temperature parts appear alternately.
(L) In addition, the position of the portion where the plate thickness decreases due to elongation, that is, the position of the metal plate that should be temperature-set according to the degree of processing can be specified by an experiment conducted in advance.
(M) Therefore, the metal plate material is held and conveyed so that a predetermined portion of the metal plate material, that is, a portion that receives either or both of the draw molding and the foam molding during the press molding is in contact with the hand portion, If press forming is started after setting the temperature of the part in contact with the hand part to a temperature corresponding to the degree of processing of draw forming or foam forming, local metal thinning and breakage of the metal plate material to be formed may occur. In addition, it is possible to perform molding such as draw molding with hot press and form molding with severe curvature.

(N) Furthermore, not only the temperature setting before the press start by the above method but also the moldability is further improved by controlling the cooling rate of each part of the metal plate material after the start of forming. That is, in the conveying stage, the temperature of the contact part with the hand part is set to a temperature corresponding to the degree of processing of each part of the press-molded product, and then press-molding is started. By controlling the cooling rate, the draw moldability and form moldability by hot pressing are further improved.
(O) And as a predetermined cooling means for controlling the cooling rate of each part of the metal plate material after the start of molding, it is desirable to cool by discharging refrigerant from a plurality of refrigerant discharge ports provided on the surface of the mold. In addition, by sequentially collecting the refrigerant from a plurality of refrigerant collection ports provided on the mold surface, the cooling efficiency and controllability by the refrigerant discharge are further improved.

  Based on the above knowledge, the present inventor rationally solves the problem that temperature unevenness occurs in the metal plate material during conveyance and the problem that post-processing becomes difficult due to excessive increase in quenching hardness, and press A hot press molding method and apparatus capable of arbitrarily setting the quenching hardness of each part of the molded product, and a metal plate material heat treatment method and apparatus capable of arbitrarily setting the quenching hardness of each part of the metal sheet. did. Furthermore, the present inventors have come up with a hot press molding method and apparatus capable of drawing molding and foam molding with severe curvature. The gist is as follows.

(1) A hot press in which a metal plate material heated by a heating device is conveyed to a mold constituting a press molding apparatus by a conveyance device having a hand portion that holds the metal plate material, and the metal plate material is molded using the mold. In the forming method, the metal plate material is held and transported so that a predetermined part of the metal plate is in contact with the hand part, and the temperature of the part in contact with the hand part is made different from the temperature of other parts by contact heat removal. After that, a hot press forming method characterized by starting press forming.
(2) Hot press in which the metal plate material heated by the heating device is conveyed to a mold constituting the press molding apparatus by a conveyance device having a hand portion that holds the metal plate material, and the metal plate material is molded using the mold. In the forming method, the metal plate material is held and transported so that a predetermined part of the metal plate is in contact with the hand part, and the temperature of the part in contact with the hand part is made different from the temperature of other parts by contact heat removal. After the transported metal plate is set in the mold, at least one state before molding, during molding, after molding, by discharging refrigerant from a plurality of refrigerant discharge ports provided on the mold surface, or A hot press forming method characterized in that the temperature of an arbitrary part of the metal plate material is controlled by refrigerant discharge from a plurality of refrigerant discharge ports provided on the surface and refrigerant recovery from the refrigerant recovery port.

(3) When the hand part is constituted by a suction pad or a clamp provided with either one or both of a heating means and a cooling means, and when the metal plate material is conveyed by being sandwiched by the suction pad or by the clamp The hot press as set forth in (1), wherein the temperature of the portion in contact with the hand part is controlled by one or both of contact heat removal or cooling by a cooling means and temperature rise by a heating means Molding method.
(4) When the hand part is constituted by a suction pad or a clamp provided with either one or both of a heating means and a cooling means, and when the metal plate material is conveyed by being sandwiched by the suction effect of the suction pad or by the clamp The hot press according to (2) above, wherein the temperature of the part in contact with the hand part is controlled by one or both of contact heat removal or cooling by a cooling means and temperature rise by a heating means Molding method.

(5) The refrigerant discharge is controlled by one or more parameters selected from the refrigerant discharge amount, discharge flow rate, discharge pressure, discharge time, and discharge timing, and each refrigerant discharge port or a plurality of refrigerants The hot press molding method according to (2) or (4), wherein refrigerant discharge from the discharge ports is grouped and controlled for each group.
(6) The predetermined part of the metal plate material is a part that undergoes machining after press molding, or a part that receives one or both of draw molding and foam molding during press molding, and a part that contacts the hand part Any one of the above (1) to (5) is characterized in that the temperature is set to a temperature corresponding to the strength of the part subjected to machining or a temperature corresponding to the degree of processing of draw molding or foam molding. The hot press molding method according to item.
(7) The hot press forming method according to any one of (1) to (6), wherein the metal plate material is a steel plate.
(8) The hot press forming method according to (7), wherein the steel sheet is a steel sheet that undergoes martensitic transformation or bainite transformation.

(9) In a heat treatment method for a metal plate material in which a metal plate material heated by a heating device is conveyed to a cooling device by a conveying device having a hand portion that holds the metal plate material, and is quenched by cooling with a predetermined cooling means in the cooling device. By holding the metal plate material so that a predetermined part of the metal plate material comes into contact with the hand part, and by making the temperature of the part in contact with the hand part different from the temperature of other parts by contact heat removal, A heat treatment method for a metal plate material, wherein the quenching hardness of the metal plate material is made different between a contact portion with the hand portion and another portion.
(10) When the hand part is constituted by a suction pad or a clamp provided with either one or both of a heating means and a cooling means, and when the metal plate material is conveyed by being sandwiched by the suction effect of the suction pad or by the clamp The temperature of the part in contact with the hand part is arbitrarily controlled by either one or both of contact heat removal or cooling by the cooling means and temperature rise by the heating means, thereby quenching and hardening the part in contact with the hand part. The heat treatment method for a metal sheet according to (9), wherein the thickness is arbitrarily set.

(11) The predetermined part of the metal plate material is a part that undergoes machining after quenching, and the temperature of the part that contacts the hand part is set to a temperature according to the strength of the part that undergoes machining. (9) or (10), characterized in that the metal plate material heat treatment method.
(12) The heat treatment method for a metal plate according to any one of (9) to (11), wherein the metal plate is a steel plate.
(13) The heat treatment method for a metal sheet according to (12), wherein the steel sheet is a steel sheet that undergoes martensitic transformation or bainite transformation.

(14) In a hot press molding apparatus comprising a heating device for heating a metal plate material, a transport device for transporting the heated metal plate material, and a mold for press-molding the transported metal plate material, the transport device is a metal plate material. A hot press molding apparatus comprising: a hand portion that can contact a predetermined portion of the member and that makes the temperature of the contacted portion different from the temperature of the other portion by contact heat removal.
(15) The said hand part is comprised by the suction pad or clamp provided with any one or both of the heating means which heats up a metal plate material, and the cooling means which cools a metal plate material, Said 14 characterized by the above-mentioned. Hot press forming equipment.

(16) The hand portion has a structure that can be separated into a portion that contacts the metal plate and a portion other than the portion, and can change at least one of the shape, size, and material of the portion that contacts the metal plate. The hot press molding apparatus according to (14) or (15).
(17) The above-mentioned (14), wherein the predetermined part of the metal plate material is a part that undergoes machining after press forming, or a part that receives either or both of draw forming and foam forming during press forming. The hot press molding apparatus according to any one of (1) to (16).
(18) A refrigerant supply pipe having a plurality of refrigerant discharge ports on a surface thereof, communicating with each of the refrigerant discharge ports, and having at least one of an on-off valve, a flow rate adjustment valve, and a pressure adjustment valve. The hot press molding apparatus according to any one of the above (14) to (17), wherein

(19) The above-mentioned molds (14) to (18), wherein the mold is a mold having a plurality of refrigerant recovery ports on the surface and provided therein with a refrigerant recovery pipe communicating with each refrigerant recovery port. The hot press molding apparatus according to any one of the above.
(20) The mold has a plurality of protrusions having an area ratio of 1 to 90%, a diameter or a circumscribed circle diameter of 10 μm to 5 mm, and a height of 5 μm to 1 mm on the surface (14). The hot press molding apparatus according to any one of to (19).

(21) In a heat treatment apparatus for a metal plate material comprising a heating device that heats a metal plate material, a conveyance device that conveys the heated metal plate material, and a cooling device that quenches the conveyed metal plate material, the conveyance device comprises a metal plate material A heat treatment apparatus for a metal plate material, comprising: a hand part that can contact a predetermined part and that makes the temperature of the part to be contacted different from the temperature of another part by contact heat removal.
(22) In the above (21), the hand part is constituted by a suction pad or a clamp provided with either or both of a heating means for raising the temperature of the metal plate material and a cooling means for cooling the metal plate material. The heat processing apparatus of the metal plate material of description.

(23) The hand part has a structure that can be separated into a part that contacts the metal plate and a part other than the part, and can change at least one of the shape, size, and material of the part that contacts the metal plate. The metal plate material heat treatment apparatus according to (21) or (22).
(24) The heat treatment apparatus for a metal plate according to any one of (21) to (23), wherein the predetermined portion of the metal plate is subjected to machining after quenching.

(A) According to the hot press forming method according to the present invention, the problem that temperature unevenness occurs in the metal plate during transport, which has been a problem in conventional hot press forming, and the quenching hardness after press forming are low. It is possible to rationally solve the problem that post-processing becomes difficult due to excessive rise. Specifically, in the past, various methods have been used to deal with each problem, but the part that needs post-processing comes into contact with the hand part of the transport device, or post-processing is necessary. According to the present invention in which the metal plate material is held and transported so that only the proper part contacts the hand part of the transport device, both problems can be solved simultaneously with great ease without impairing productivity.
Furthermore, in order to solve the latter problem by the conventional method, a processing step is required to partially change the quenching hardness of the press-molded product after conveyance, for example, after setting the metal plate material in the mold. However, according to the present invention that actively controls the temperature of the metal plate material while transporting, particularly the temperature control at the contact portion, the processing step can be omitted or the processing time can be shortened, and the productivity can be reduced. Can be improved.

(B) Moreover, since the hand part is constituted by a suction pad or a clamp, it becomes easy to bring the hand part into contact with a predetermined part of the metal plate material, for example, a part subjected to machining after press molding, or after press molding It becomes easy to contact the hand part only to the part subjected to machining, and further, if the hand part is constituted by a suction pad or the like provided with either one or both of the heating means and the cooling means, the temperature of the contact part is Since it can be controlled by either or both of contact heat removal or cooling by the cooling means and temperature rise by the heating means, the quenching start temperature of the contact part can be set to a temperature according to the strength of the part subjected to machining, Thereby, the quenching hardness of a contact part can be set arbitrarily. Specifically, the quenching hardness of each part of the molded product can be made uniform by raising the temperature of the contact part by a heating means provided on a suction pad or the like and making the temperature of each part of the metal plate material uniform. On the other hand, for parts that require post-processing such as drilling (piercing) or cutting (trim), that is, parts that do not require quenching hardness, the quenching start temperature of the contact part is set to the contact heat removal from the hand part. The quenching hardness can be lowered by lowering by cooling by a cooling means provided in the hand portion. Further, if the press molding is started after the temperature of the metal plate material is changed for each part of the molded product, it is possible to obtain a press-formed product having different quenching hardness for each part of the molded product.

(C) Further, after the metal plate material is set in the mold constituting the hot press forming apparatus, the refrigerant is discharged from the plurality of refrigerant discharge ports provided on the mold surface, or the plurality of provided on the mold surface. Since either one or both of the quenching start temperature and the cooling rate of each part of the metal plate material can be arbitrarily controlled by the refrigerant discharge from the refrigerant discharge port and the refrigerant recovery from the refrigerant recovery port, the quenching hardness of each part of the press-formed product can be controlled. It can be set arbitrarily according to the purpose. That is, according to the present invention, the quenching hardness of each part of the press-formed product is set accurately and arbitrarily according to the purpose without joining a plurality of metal plate materials having different plate thicknesses and strengths as in the tailored blank by welding. be able to. Needless to say, the quenching hardness of the press-formed product can be made uniform. Specifically, for parts that require strength, increasing the cooling rate can increase the strength by martensite transformation or bainite transformation, while drilling (piercing) or cutting (trim). For parts that require post-processing such as quenching hardness, lower the quenching start temperature before press molding, or increase the cooling rate during or after molding. Hardening can be reduced by weakening. Also, if press molding is started after changing the temperature of the metal plate material for each part of the molded product, it is possible to obtain a press-molded product with different quenching hardness for each part of the molded product, and after molding and after molding If the cooling rate of the metal plate material in either one or both is made different for each part of the molded product, press molded products having different quenching hardnesses for each part of the molded product can be obtained.

(D) Moreover, according to the hot press molding method according to the present invention, it is possible to perform draw molding or form molding with severe curvature, which cannot be realized by the conventional hot press molding method. Specifically, when the conventional hot press molding technique is used to perform the draw molding represented by deep drawing, etc., there is a problem that local thinning or breakage occurs in the stretched portion. In the hot press forming method according to the present invention, a predetermined part of the metal plate material, that is, a part that receives one or both of draw forming and foam forming during press forming is in contact with the hand part, or The metal plate is held and transported so that only the part that receives either or both of the draw molding and the foam molding is in contact with the hand part during press molding, and the temperature of the part in contact with the hand part is drawn. Alternatively, press molding is started after setting the temperature according to the degree of processing of foam molding, so the strength of the part where elongation occurs and breakage may be raised in advance. An ability, as a result, it is possible to achieve load distribution of the portion where the elongation occurs, it is possible to prevent breakage.
Furthermore, not only the temperature setting before the press start by the said method but the formability can be further improved by controlling the cooling rate of each part of the metal plate material after the start of forming. Specifically, a predetermined part of the metal plate material, that is, a part that receives one or both of draw molding and foam molding during press molding is in contact with the hand part, or draw molding during press molding. The metal plate is held and transported so that only one or both of the parts for foam molding are in contact with the hand part, and the temperature of the part in contact with the hand part depends on the degree of processing of draw molding or foam molding Press forming is started after the temperature has been set, and after the start of forming, by controlling the cooling rate of each part of the metal plate by a predetermined cooling means, the load distribution in the part where elongation occurs can be controlled more accurately As a result, it is possible to further improve draw moldability and foam moldability by hot pressing.
(E) Furthermore, since cooling by refrigerant discharge is performed, it goes without saying that a press product having excellent shape freezing property and good dimensional accuracy can be manufactured. In addition, productivity can be improved by shortening the holding time in the mold.

(F) Further, according to the heat treatment method for a metal plate material according to the present invention, the problem that temperature unevenness occurs in the metal plate material during conveyance, which has been a problem in the conventional heat treatment method for metal plate material, and the quenching hardness is increased. It is possible to rationally solve the problem that post-processing becomes difficult due to too much. Specifically, conventionally, various methods have been used to cope with each problem, but a predetermined part of the metal plate material, for example, a part that needs to be post-processed, comes into contact with the hand unit of the transport device. Or, according to the present invention in which the metal plate material is held and transported so that only a portion requiring post-processing is in contact with the hand portion of the transport device, both problems can be solved very easily without impairing productivity. Can be solved at the same time. In other words, according to the present invention that actively controls the temperature of each part of the metal sheet while being conveyed, the processing step for partially changing the quenching hardness of the metal sheet after the conveyance can be shortened. And productivity can be improved.

(G) Further, since the hand part is constituted by a suction pad or a clamp, it becomes easy to bring the hand part into contact with a predetermined part of the metal plate material, for example, a part that requires post-processing, or post-processing is required. It is easy to bring the hand part into contact with only a certain part, and further, if the hand part is constituted by a suction pad or the like provided with either one or both of the heating means and the cooling means, the temperature of the contact part is reduced to the contact heat removal Alternatively, either one or both of cooling by the cooling means and heating by the heating means can be set to a temperature according to the strength of the part subjected to machining, so that the quenching start temperature of the contact part can be arbitrarily controlled. Accordingly, the quenching hardness of the contact portion can be arbitrarily set. Specifically, the temperature of the contact portion is raised by a heating means provided on a suction pad or the like, and the quenching hardness of each part of the metal plate material can be made uniform by making the temperature of each part of the metal plate material uniform. For parts that require post-processing such as drilling (piercing) or cutting (trimming), that is, parts that do not require quenching hardness, the quenching start temperature of the contact part is set in advance to the temperature of the surrounding part in the conveying stage. By lowering the thickness, the quenching hardness of the contact portion, that is, the portion that requires post-processing can be reduced as compared with the surrounding portion.

Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS.
FIG. 2 is a schematic explanatory view of a hot press forming apparatus according to the present invention.
3A and 3B are explanatory views showing an example of a transport device according to the present invention, in which FIG. 3A is a diagram illustrating a case where the hand unit is configured by a suction pad, and FIG. 3B is a diagram illustrating a temperature distribution of the metal plate after transport. (C) is a figure which shows distribution of quenching hardness of a press-formed product.
4A and 4B are explanatory views showing another example of the transport apparatus according to the present invention, in which FIG. 4A shows a case where the hand portion is configured by a clamp, and FIG. 4B shows a temperature distribution of the metal plate after transport. FIG. 4C is a diagram showing the distribution of quenching hardness of the press-formed product.
FIG. 5 is a schematic explanatory view of a mold constituting the hot press forming apparatus according to the present invention, (a) is a diagram showing a die holder and a punch holder, and (b) is for clarifying the structure of the apparatus. It is the figure which abbreviate | omitted and indicated the die holder and the punch holder.
FIG. 6 is an explanatory view showing a mold having a refrigerant discharge function according to the present invention, and is a cross-sectional view when the punch has the function.
FIG. 7 is an explanatory view showing an example of a mold according to the present invention, and is a view showing a surface of the mold on which a refrigerant discharge port, a refrigerant recovery port, and a protrusion are formed.
FIG. 8 is a cross-sectional view showing an example of a mold according to the present invention, and is a view showing a cross section of a mold in which a refrigerant discharge port, a refrigerant recovery port, and a protrusion are formed.
FIG. 9 is a cross-sectional view showing another example of the mold according to the present invention, and is a view showing a cross section of the mold in which a refrigerant discharge port, a refrigerant recovery port, and a protrusion are formed.
FIG. 10 is a schematic explanatory view of a heat treatment apparatus for a metal plate material according to the present invention.

As shown in FIG. 2, the hot press forming method according to the present invention is a hot press forming apparatus in which a metal plate 1 heated by a heating device 51 such as a heating furnace is transported by a conveying device 30 having a hand portion 35 for holding the metal plate material 1. 2, the metal plate 1 is formed using the mold, and the first feature is that a predetermined portion of the metal plate 1 is in contact with the hand portion 35. In this way, the metal plate material 1 is held and transported, and the temperature of the part that comes into contact with the hand part 35 is changed from the temperature of other parts by contact heat removal, and then press forming is started, and the part that comes into contact with the hand part It is to obtain a press-molded product 60 having different quenching hardness at different parts.
The second feature of the hot press forming method according to the present invention is that the hand portion 35 is constituted by a suction pad or a clamp provided with either one or both of the heating means 42 and the cooling means 43 to remove contact. Either or both of heat or cooling by the cooling means 43 and temperature rise by the heating means 42 are set to a temperature corresponding to the strength of the part to be machined, and then press forming is started. The quenching hardness of the contact portion, that is, the portion subjected to machining is arbitrarily set.
Further, the third feature of the hot press forming method according to the present invention is that, after setting the metal plate 1 having controlled the quenching start temperature of the contact site by the above method in the mold, more specifically, before forming. In at least one state during molding and after molding, refrigerant discharge from the plurality of refrigerant discharge ports 12 provided on the mold surface, or refrigerant discharge and refrigerant from the plurality of refrigerant discharge ports 12 provided on the mold surface By recovering the refrigerant from the recovery port 17, one or both of the quenching start temperature and the cooling rate of each part of the metal plate material is controlled to arbitrarily set the quenching hardness of each part of the press-formed product.
Further, the fourth feature of the hot press molding method according to the present invention is the contact heat removal with the hand part in the conveying stage, the refrigerant discharge from a plurality of refrigerant discharges provided on the mold surface, etc. By controlling the strength of each part of the metal plate material, draw molding by hot pressing and foam molding with severe curvature are performed.
Hereinafter, in order to describe in detail the features of the above-described hot press forming method according to the present invention, (1) a molding material used in the present invention and its heating method, (2) a heated metal sheet material conveying device, (3 ) A mold (mold having a refrigerant discharge function) for forming the conveyed metal plate material and (4) a method and apparatus for controlling refrigerant discharge will be described in order.

(1) First, the molding material used in the hot press molding method according to the present invention and the heating method and heating temperature of the molding material before conveyance will be described.
The molding material used in the present invention is a metal plate 1 and can be applied to any steel plate such as an Al-plated steel plate, a Zn-plated steel plate, a high-strength steel plate, and ordinary steel.
Further, a steel plate that undergoes martensitic transformation or bainite transformation can be increased in strength by quenching by refrigerant discharge or contact heat removal with a mold, and therefore, a steel plate that undergoes martensitic transformation or bainite transformation is desirable. It should be noted that the transformation is not necessarily performed when the refrigerant is discharged or when the contact heat is removed from the mold, and the transformation may be performed after molding.
The method of heating the metal plate 1 is not particularly limited, and any method that can heat the metal plate 1 to the A1 transformation point or higher, heating in an electric furnace, gas furnace, flame heating, current heating, high frequency Any method such as heating or induction heating may be used.

(2) Next, the conveying device 30 for conveying the metal plate 1 heated to the A1 transformation point or higher by the above method to the mold will be described.
The conveying apparatus 30 which comprises the hot press molding apparatus 2 which concerns on this invention is comprised from the base part 31, the arm 32, and the hand part 35 holding the heated metal plate 1 as shown in FIGS. However, one of the features of the present invention is that a predetermined part of the metal plate 1, for example, a part that undergoes machining after press molding, or a part that receives either or both of draw molding and foam molding during press molding. Since the metal plate 1 is held and transported so as to be in contact with the hand portion 35, the hand portion 35 is constituted by a suction pad 37 that can be easily brought into contact with a predetermined part of the metal plate 1 The clamp 44 is preferably used.

  First, the case where the hand part 35 is comprised by the suction pad 37 is demonstrated using FIG. The hand unit 35 includes a suction pad 37 for adsorbing the metal plate 1 that is a conveyance object, and a frame 36 for attaching the suction pad 37 to the arm 32 of the conveyance device. The suction pad 37 includes a conduit 38, a skirt portion 39, a pad portion 40, and a sealing material 41, and the conduit 38 and the vacuum generator 33 are connected by a vacuum hose 34. That is, the suction mechanism of the transport device 30 constituted by the suction pad 37 generates a vacuum by the vacuum generation device 33, and vacuums or depressurizes the suction pad 37, more specifically, the inside of the skirt portion 39. This is achieved by holding the metal plate 1 that is the object to be conveyed by (suction adsorption force).

The skirt portion 39 sucks air from the inside of the skirt portion by suction by the vacuum generator 33 connected by the conduit 38 and the vacuum hose 34, and vacuums or depressurizes the space formed between the suction pad 37 and the metal plate 1. It is a part of.
The material constituting the skirt portion 39 is not particularly limited as long as the metal plate 1 heated to a high temperature or a material having sufficient hot strength with respect to the ambient temperature can be obtained, but carbon steel that can be easily processed and lined. , Stainless steel, heat-resistant alloy, cermet, graphite and ceramics, and preferably one or a combination of two or more.

Moreover, also about the pad part 40 which is a site | part which contacts the metal plate material 1, similarly to the skirt part 39, from carbon steel, stainless steel, a heat-resistant alloy, cermet, a graphite, or the combination of 2 or more of ceramics. It is desirable to configure.
For example, in the case where durability in a high temperature range where the temperature of the metal plate 1 is 200 to 700 ° C. is required, it is effective to configure the pad portion 40 with a heat-resistant alloy. Therefore, it is desirable that the material be made of any one or a combination of two or more of an Fe-based alloy, Ni-based alloy, Co-based alloy, and particle dispersion strengthened alloy. Since these are heat-softening materials, sufficient and not excessive softening occurs in this temperature range, and sealing properties can be secured.
Moreover, when conveying the metal plate 1 in a temperature range of 500 to 1500 ° C. higher than the allowable temperature of the heat-resistant alloy, it is desirable to configure the pad portion 40 with ceramics or graphite. It is desirable to be made of any one or a combination of two or more of alumina, silica, chromia, titania, zirconia, silicon nitride, silicon carbide, titanium boride, and silicon boride that can be shaped. Ceramics hardly soften by heat with respect to the heat-resistant alloy, but in this temperature range, the surface of the object to be heated is sufficiently softened to ensure sealing performance.
Moreover, when conveying the metal plate 1 in a temperature range of 200 to 500 ° C., it is possible to use economically advantageous carbon steel or stainless steel for the pad portion 40.

In order to improve the suction capacity of the suction pad 37, it is useful to increase the degree of vacuum of the space formed between the suction pad 37 and the metal plate material 1, and for that purpose, the pad portion 40 and the metal plate material 1 It is effective to arrange the sealing material 41 at the boundary.
As the sealing material 41, it is desirable to use a heat softening material, and it is desirable that the sealing material 41 is composed of one or a combination of two or more of glass, metal, alloy, and expanded graphite. The glass material is soda glass (Na ₂ O—CaO—SiO ₂ glass), crystallized glass (silicate glass, aluminosilicate glass, borate glass, borosilicate glass, phosphosilicate glass), Quartz glass, solder glass, crystalline solder glass, lanthanum glass, neutral glass, lead glass, hydrous phosphate glass, tellurite glass, chalcogenide glass, foam glass, or a combination of two or more Is possible. The fixing to the pad portion 40 is not particularly limited as long as it can be fixed with a strength that does not hinder the holding and fixing of the metal plate 1, but is fixed by mechanical fitting, screwing, pinning, or fastening by friction. Is desirable. Moreover, the method by thermal spraying or application | coating is also possible.
It is also possible to apply a metal or alloy that softens at high temperatures to the sealing material 41. The metal or alloy is iron, cobalt, nickel, beryllium, manganese, copper, gold, silver, calcium, barium, aluminum, magnesium, strontium, zinc, antimony, tin, lead, or a combination of two or more An alloy made of The fixing to the pad portion 40 in this case is not particularly limited as long as it can be fixed with a strength that does not hinder the holding and fixing of the metal plate 1, but is mechanically engaged, screwed, pinned, and fastened by friction. Fixing by is desirable. Moreover, the method by thermal spraying or plating is also possible.

The pad portion 40 and the skirt portion 39 may be integrally formed. However, it is desirable that the pad portion 40 and the skirt portion 39 be separated from each other. More preferably, the pad portion 40 can be removed while the suction pad 37 is fixed to the frame 36. It is desirable to keep it. Similarly, regarding the attachment of the suction pad 37 to the frame 36, it is desirable that the suction pad 37 be attached to an arbitrary position of the frame 36. With such a structure, it is possible to form contact portions of various shapes and sizes on the metal plate material by exchanging the shape and size of the pad portion 40 that is a portion in contact with the metal plate material 1. Become. Moreover, when the pad part 40 from which a material, especially heat conductivity differs is used, the heat removal effect in a contact site | part can be changed. Further, by changing the attachment position of the suction pad 37, it is possible to form a contact site at a predetermined position of the metal plate 1.
That is, by adjusting at least one of the attachment position of the suction pad 37 and the shape, size, and material of the pad portion 40, the first feature of the hot press forming method according to the present invention, that is, the metal plate 1 3, for example, as shown in FIG. 3A, the metal plate 1 can be adsorbed and transported so that a portion necessary for post-processing (piercing, trim, etc.) is in contact with the pad portion 40. As a result, as shown in FIG. 3B, the temperature of the contact portion with the pad portion 40 differs from the temperature of other portions due to contact heat removal, so that the contact with the pad portion 40 as shown in FIG. The quenching hardness of the press-formed product can be made different between the part and the other part, and post-processing at the part can be easily performed.
Further, as shown in FIG. 12 (d), the attachment position of the suction pad 37 so that the contact portion is formed in a portion with a high degree of processing, for example, a portion where the plate thickness decreases due to elongation associated with draw molding or foam molding. If the shape and size of the pad portion 40 are adjusted, the fourth feature of the hot press forming method according to the present invention, that is, draw forming or form forming by hot pressing can be performed.
For example, when the press-formed product 60 having the shape shown in FIG. 12B is obtained by using the metal plate 1 having the shape shown in FIG. 12A, the position of the portion where the plate thickness is reduced due to elongation by an experiment performed in advance, That is, the position of the metal plate material to be temperature set according to the degree of processing is specified, and the attachment position of the suction pad 37 and the shape, size, and size of the pad portion 40 are set so that the contact part is formed at the position. If the metal plate 1 is transported after adjusting at least one of the materials, the temperature of the contact part is lower than the temperature of the other part due to contact heat removal with the pad portion 40. It rises above the site.
Therefore, the metal plate 1 is held and transported so that the portion that receives either or both of the draw molding and the foam molding during the press molding is in contact with the pad portion 40, and the temperature of the portion in contact with the pad portion 40 is set. If the press molding is started after setting the temperature according to the degree of processing of the draw molding or the foam molding, the other part having a lower strength than the contact part is extended as shown in FIG. It is possible to perform draw forming by hot pressing or form forming with a severe curvature without causing local metal thinning or breakage of the metal sheet 1.
The position of the portion where the plate thickness decreases due to elongation, that is, the position of the metal plate material that should be temperature-set according to the degree of processing, can be specified by experiments conducted in advance. Therefore, for example, a temperature distribution having a form as shown in FIG. 12D is formed in a portion with a high degree of processing specified by an experiment performed in advance, and the temperature of the portion with a high degree of processing is set to the temperature of another portion. By lowering the strength further and lowering the strength, as shown in FIG. 12 (f), when the press molding is started, a portion having a lower strength than the portion where the strength is increased is elongated, thereby preventing breakage. be able to.
In addition, the temperature adjustment area | region 64 shown in FIG.12 (d) and FIG.12 (e) shows having adjusted the temperature of the said area | region by contact heat removal etc., For example, the temperature of the said temperature adjustment area | region 64 is shown. If it is set lower than the peripheral region, the strength in the temperature adjustment region 64 is higher than that in the other portions. Therefore, as shown in FIG. Since other low-strength parts are elongated, breakage can be prevented.
In addition, the form of the temperature distribution to be applied to the metal plate 1 before the start of pressing is not limited to the form shown in FIG. 12 (d), and a temperature distribution corresponding to the degree of processing of the press-formed product 60 is formed. Is desirable. For example, in the press-formed product 60 shown in FIG. 12 (b), the vertical wall portion 62 is the part with the highest degree of processing, but the metal plate material corresponding to this is shown in FIG. 12 (e). If the temperature distribution of the form, that is, the temperature distribution in which the high-strength and low-strength portions appear alternately, load concentration on the part with a high degree of processing, in other words, the part where elongation occurs Can be prevented, and breakage can be prevented.
In addition, the attachment structure of the pad portion 40 to the skirt portion 39 or the attachment structure of the suction pad 37 to the frame 36 is not particularly limited as long as it can be fixed with a strength that does not hinder fixation. Fitting, screwing, pinning, etc. are desirable.

Further, by providing either one or both of the heating means 42 and the cooling means 43 in the pad portion 40, the second feature of the hot press forming method according to the present invention can be realized. That is, the hand portion is configured by a suction pad including either one or both of the heating unit 42 and the cooling unit 43, and either one or both of contact heat removal or cooling by the cooling unit 43 and temperature increase by the heating unit 42 are used. By setting the quenching start temperature of the contact part to a temperature corresponding to the strength of the part subjected to machining, and then starting press molding, it is possible to arbitrarily set the quenching hardness of the contact part .
Specifically, the hardness of each part of the molded product can be made uniform by raising the temperature of the contact part by the heating means provided on the suction pad and making the temperature of each part of the metal plate material uniform. For parts that require post-processing such as drilling (piercing) or cutting (trimming), that is, parts that do not require quenching hardness, the quenching start temperature of the contact part is removed from the suction pad or suctioned with the suction pad. The quenching hardness can be lowered by lowering by cooling by a cooling means provided on the pad. If press molding is started after changing the temperature of the metal plate material for each part of the molded product, it is possible to obtain press-formed products having different quenching hardness for each part of the molded product.
Moreover, by providing either one or both of the heating means 42 and the cooling means 43 in the pad part 40, the draw moldability and foam moldability by the hot press described above can be further improved. For example, in the method in which the temperature of the contact portion is set to a temperature according to the degree of processing of draw molding or foam molding by contact heat removal with the pad portion 40, only cooling by contact heat removal can be realized. There is a risk of overcooling the part to give more strength than necessary, but by providing the pad section 40 with the heating means 42, this can be avoided, and the temperature of the contact part can be set arbitrarily. It becomes possible. Further, if the pad section 40 is provided with the cooling means 43, the cooling efficiency is improved, so that the cooling time can be shortened and the productivity is also improved.
Examples of the heating means 42 include an electric heater, a gas burner, an induction coil, and the like, and the temperature of the contact portion can be raised by any one or a combination of two or more thereof. The gas burner is preferably a radiant type. Moreover, as a cooling means 43, it is possible to cool a contact site | part by arranging a water channel in the pad part 40 and always letting water flow.

Next, the case where the hand part 35 is comprised by the clamp 44 is demonstrated using FIG. The clamp 44 includes an upper clamp plate 45, a lower clamp plate 46, a cylinder 47, and a guide 48. The clamp 44 has a mechanism in which the upper clamp plate 45 is moved up and down by the cylinder 47, and the metal plate 1 is sandwiched between the clamp plates. A claw portion 49 is disposed.
The material constituting the upper clamp plate 45 and the lower clamp plate 46 is not particularly limited as long as the metal plate 1 heated to a high temperature or a material having sufficient hot strength against the ambient temperature can be obtained. It is desirable that it is made of any one of carbon steel, stainless steel, heat-resistant alloy, cermet, graphite and ceramics, or a combination of two or more.

Further, the claw portion 49 which is a portion in contact with the metal plate 1 is also composed of one or a combination of two or more of carbon steel, stainless steel, heat-resistant alloy, cermet, graphite or ceramics, like the clamp plate. It is desirable to do.
The claw portion 49 and the clamp plate may be integrally formed. However, it is desirable that the claw portion 49 and the clamp plate be separated from each other, and it is preferable that the claw portion 49 be attached to an arbitrary position of the clamp plate. desirable. With such a structure, by changing the attachment position of the claw portion 49 that is a part that contacts the metal plate material 1, for example, by sliding the claw portion 49 along the clamp plate, a predetermined amount of the metal plate material 1 is obtained. It is possible to form a contact site at the position. Moreover, when the nail | claw part 49 from which a material, especially heat conductivity differs is used, the heat removal effect in a contact part can be changed.
That is, by adjusting at least one of the attachment position of the claw portion 49 and the shape, size and material of the claw portion 49, the first feature of the hot press molding method according to the present invention, that is, FIG. As shown in a), the metal plate 1 can be sandwiched and conveyed so that a predetermined portion of the metal plate 1, for example, a portion necessary for post-processing (piercing, trim, etc.) is in contact with the claw portion 49, As a result, as shown in FIG. 4 (b), the temperature of the contact portion with the claw portion 49 differs from the temperature of other portions due to contact heat removal, so that the contact with the claw portion 49 as shown in FIG. 4 (c). The quenching hardness of the press-formed product can be made different between the part and the other part, and post-processing at the part can be easily performed.
In addition, the attachment position of the claw portion 49 and the shape and size of the claw portion 49 so that the contact portion is formed in a portion with a high degree of processing, for example, a portion where the plate thickness decreases due to elongation associated with draw molding or foam molding. Is adjusted, it is possible to perform the fourth feature of the hot press molding method according to the present invention, that is, draw molding or foam molding by hot pressing.
For example, the position of the portion where the plate thickness decreases due to elongation, that is, the position of the metal plate material to be temperature-set according to the degree of processing is specified by an experiment conducted in advance, and the contact part is formed at the position. If the metal plate material 1 is transported by adjusting at least one of the attachment position of the claw portion 49 and the shape, size and material of the claw portion 49, the temperature of the contact portion is reduced by contact heat removal with the claw portion 49. Therefore, the strength of the contact portion is higher than that of the other portions.
Therefore, the metal plate 1 is held and transported so that the part that receives either or both of the draw molding and the foam molding is in contact with the claw part 49 during the press molding, and the temperature of the part in contact with the claw part 49 is set. If the press molding is started after setting the temperature according to the degree of processing of the draw molding or the foam molding, the other portion having a lower strength than the contact portion extends, so that the local reduction of the metal plate material 1 as the molding material is achieved. Draw molding by hot pressing or foam molding with severe curvature can be performed without causing meat or breakage.
The above effect can also be obtained by forming a temperature distribution in which a high strength portion and a low strength portion appear alternately in a portion with a high degree of processing by contact heat removal with the claw portion 49. be able to.
The attachment structure of the claw portion 49 to the clamp plate is not particularly limited as long as it can be fixed with a strength that does not hinder fixation, and mechanical fitting, screwing, pinning, and the like are desirable.

Further, by providing either one or both of the heating means 42 and the cooling means 43 in the claw portion 49, the second feature of the hot press forming method according to the present invention, that is, the heating means 42 and the cooling means 43 is provided. The hand part is constituted by a clamp having either one or both, and the quenching start temperature of the contact part is arbitrarily controlled by either one or both of contact heat removal or cooling by the cooling means 43 and heating by the heating means 42. Thus, it is possible to arbitrarily set the quenching hardness of the contact portion.
Further, by providing either one or both of the heating means 42 and the cooling means 43 in the claw portion 49, the draw moldability and the foam moldability by the hot press described above can be further improved. For example, in the method in which the temperature of the contact portion is set to a temperature according to the degree of processing of draw molding or foam molding by contact heat removal with the claw portion 49, only cooling by contact heat removal can be realized. There is a risk of overcooling the part to give more strength than necessary, but by providing the heating means 42 in the claw part 49, this can be avoided, and the temperature of the contact part can be arbitrarily set It becomes possible. If the claw portion 49 is provided with the cooling means 43, the cooling efficiency is improved, so that the cooling time can be shortened and the productivity is also improved.
Note that the heating means 42 includes an electric heater, a gas burner, an induction coil, and the like, and the temperature of the contact portion can be raised by any one or a combination of two or more thereof. The gas burner is preferably a radiant type. Moreover, as a cooling means 43, it is possible to cool a contact site | part by arranging a water channel in the pad part 40 and always letting water flow.

(3) Next, the metal mold | die which has a refrigerant | coolant discharge function is demonstrated in detail using FIG. As shown in FIG. 5, the mold constituting the hot press molding apparatus 2 according to the present invention includes an upper die including a die 3, a pad 5, a die holder 9 and a die base 7, a punch 4, a plate presser 6, It is comprised from the lower mold | type provided with the punch holder 10 and the die base 8. FIG. The die holder 9 also serves as a pad holder, and the punch holder 10 serves as a plate holding holder. Hereinafter, these sets are referred to as a die set 11. FIG. 5B is a diagram in which the die holder and the punch holder are omitted in order to clarify the configuration of the apparatus.

FIG. 6 is an explanatory view showing a mold having a refrigerant discharge function according to the present invention, and is a cross-sectional view when the punch 4 has the function, but the die 3, the pad 5, the punch 4, and the plate presser 6 It is desirable that at least one has a refrigerant discharge function. Hereinafter, the case where the punch 4 has a refrigerant discharge function will be described.
As shown in FIG. 6, the mold having the refrigerant discharge function according to the present invention has a plurality of refrigerant discharge ports 12 for discharging the refrigerant to the metal plate 1 as a molding material on the surface, and the refrigerant discharge port is provided inside. A refrigerant supply pipe 13 that communicates with the outlet 12 and includes at least one of an on-off valve 14, a flow rate adjustment valve 15, and a pressure adjustment valve 16 is disposed.
6 shows an example in which the coolant discharge port 12 is provided in the vertical wall portion of the punch 4, but it may be provided at the top portion or at both the vertical wall portion and the top portion. The same applies to the case where the refrigerant outlet 12 is provided in the plate holder 6. On the other hand, when the coolant discharge port 12 is provided in the upper die 3 or the pad 5, it may be provided at the bottom or at both the vertical wall and the bottom.

The refrigerant discharge port 12 and the refrigerant supply pipe 13 communicating with the refrigerant discharge port 12 can be formed by mechanical drilling by a drill or drilling by electric discharge machining. In this case, the die material is preferably hot working die steel from the viewpoint of hot strength.
In addition, since the refrigerant supply pipe 13 fulfills the refrigerant discharge function as long as it communicates with the refrigerant discharge port 12, it penetrates from the inside of the mold to the outer surface instead of drilling the refrigerant discharge port 12 and the refrigerant supply pipe 13 in the mold. The refrigerant supply pipe 13 may be connected to a porous metal having pores. In this case, it is desirable to use a porous metal having a plurality of holes having a diameter of 100 μm to 1 mm and a pitch of 100 μm to 10 mm penetrating in the thickness direction. For example, in the punch having the configuration shown in FIG. 6, if the core 20 is made of die steel and the punch 4 is made of a porous metal, the refrigerant discharge ports 12 and the refrigerant supply pipes 13 that are fine and have a small pitch can be formed. Such a porous metal can be produced by unidirectional solidification in which the direction of the solidified structure is made constant by temperature control after sintering the powder after molding or by melting the metal.
In the hot press molding method and apparatus according to the present invention, the coolant is discharged by such a mold and press molding is performed, but rapid cooling is not required as the refrigerant is used, and the processing is not severe. When a sufficient cooling rate can be obtained by heat removal due to contact with the mold, press molding may be performed without discharging the refrigerant.

Next, functions of the on-off valve 14, the flow rate adjustment valve 15 and the pressure adjustment valve 16 of the refrigerant supply pipe 13 will be described.
In general, the cooling capacity by the refrigerant can be expressed using a heat transfer coefficient α, and the relationship between the heat transfer coefficient α, the refrigerant discharge amount Q, the discharge flow rate U, the discharge pressure P, and the discharge time T is expressed by the following equation. Can be represented. Note that f, g, and h represent functions, for example, that the heat transfer coefficient α is established as a function of the refrigerant discharge amount Q.
Heat transfer coefficient α = f (refrigerant discharge amount Q) (1)
Refrigerant discharge amount Q = g (discharge flow velocity U, discharge time T) (2)
Discharge flow rate U = h (discharge pressure P) (3)

That is, according to the present invention, the refrigerant discharge amount Q, the discharge flow velocity U, the discharge pressure P, the discharge time T, and the at least one of the on-off valve 14, the flow rate adjusting valve 15 and the pressure adjusting valve 16 of the refrigerant supply pipe 13 are One or more parameters selected from the discharge timing are controlled, thereby controlling the heat transfer coefficient. That is, in the present invention, it is not always necessary to provide three types of valves, that is, the on-off valve 14, the flow rate adjusting valve 15, and the pressure adjusting valve 16, and the function can be achieved by one valve. However, by providing three types of valves, that is, the on-off valve 14, the flow rate adjusting valve 15, and the pressure adjusting valve 16, the parameters can be easily controlled. It is desirable to provide a type of valve.
The valve may be built in the mold close to the refrigerant discharge port 12 in order to keep the responsiveness good. However, it takes time to disassemble the mold every time the valve is adjusted. It is desirable to install in.

Further, as described above, the present invention controls one or more parameters selected from the refrigerant discharge amount Q, the discharge flow rate U, the discharge pressure P, the discharge time T, and the discharge timing by at least one valve. Thus, the heat transfer coefficient α by the refrigerant discharge is controlled. If this control is performed for each refrigerant discharge port, the heat transfer of the cooling by the refrigerant discharge from the plurality of refrigerant discharge ports provided on the mold surface is performed. It becomes possible to freely vary the coefficient α, thereby arbitrarily controlling the quenching start temperature and cooling rate of each part of the metal plate material, which is the third feature of the hot press forming method according to the present invention, The quenching hardness of each part of the press-formed product can be arbitrarily set. In addition, since the heat transfer coefficient α can be freely changed, the strength of each part of the metal plate material can be arbitrarily controlled, so that local thinning and breakage do not occur when draw forming or foam forming is performed. The portions with low strength can be stretched one after another, and the elongation and thickness of each portion of the metal plate material can be freely controlled.
Furthermore, when forming a columnar press product, moldability can be improved by grouping and controlling the refrigerant discharge from a plurality of refrigerant discharge ports in a positional relationship where the punch push-in amount is the same. It is possible.

7 and 8, a plurality of refrigerant recovery ports 17 are formed on the molding surface of the mold, and a refrigerant recovery pipe 18 communicating with the refrigerant recovery port 17 is arranged inside the mold. The refrigerant discharged to the metal plate 1 can be efficiently recovered.
Furthermore, the cooling efficiency can be improved by recovering the refrigerant from the refrigerant recovery pipe 18 by suction means such as a vacuum generator. This is because the refrigerant that has not been vaporized adheres to or accumulates along the molding surface of the mold, for example, on the bottom of the protrusion 19 described later, and contributes to cooling in the adhering part. This is because, when the refrigerant is newly discharged, the heat transfer coefficient α at the adhering portion or the like is lowered as compared with the case where the refrigerant does not remain. For this reason, after the refrigerant is discharged, it is desirable to collect the refrigerant that has not been vaporized by a suction means such as a vacuum generator, thereby improving the control efficiency of the cooling efficiency and the heat transfer coefficient α.
The refrigerant recovery port 17 and the refrigerant recovery tube 18 can be formed by a method similar to the method of forming the refrigerant discharge port 12 and the refrigerant supply tube 13 described above. Moreover, the refrigerant | coolant collection | recovery port 17 may be provided in the top part of the punch 4, and may be provided in both a vertical wall part and a top part. The same applies to the case where the refrigerant recovery port 17 is provided in the plate holder 6. On the other hand, when the coolant recovery port 17 is provided in the upper die 3 or the pad 5, it may be provided at the bottom or at both the vertical wall and the bottom, but is provided at the vertical wall. Thus, the refrigerant discharged to the molding material can be efficiently recovered.

Further, as shown in FIGS. 7 and 8, if a plurality of protrusions 19 are formed on the molding surface of the mold, the contact area between the mold and the metal plate 1 is reduced, and due to heat removal from the mold during press molding. It is possible to suppress overcooling of the metal plate material that is the molding material. Conversely, by increasing the contact area between the material to be molded and the refrigerant, a large amount of refrigerant can be brought into contact with the portion to be rapidly cooled, and the cooling rate can be increased as required. Furthermore, when the refrigerant is discharged at the bottom dead center after the completion of molding, it becomes easy to circulate the refrigerant in the gap between the protrusion 19 and the metal plate 1, and the cooling efficiency between the mold and the metal plate 1 is improved. Can be increased. In addition to this, the thermal distortion of the mold can be reduced and the processing accuracy can be increased.
7 and 8 are cylindrical shapes provided at predetermined intervals on the molding surface of the mold, but the horizontal cross-sectional shape is circular, polygonal, or star-shaped. It is desirable that the shape of the vertical cross section is either rectangular or trapezoidal, and may be hemispherical.

The protrusion 19 can exert the above-described effect if it is formed on at least one of the molding surfaces of the mold, but may be formed on both molding surfaces. Further, it may be provided on a part of the molding surface of the mold or on the entire surface.
The protrusion 19 may be formed as it is on the surface of the molding surface. However, depending on the molding conditions, the shape of the protrusion may be transferred to the molded product, which may impair the surface properties of the molded product. The mold part around the part is removed to form a dent, or as shown in FIG. 9, a dent having a depth matching the height of the projection part is formed in the mold part at the projection part forming position, and the dent is projected into the dent part. It is desirable to form the portion 19.

The area ratio of the protrusions 19 is preferably 1 to 90% of the molding surface of the mold. If it is less than 1%, the shape of the protrusions can be easily transferred to the material to be molded, and if it exceeds 90%, the gap between the protrusions 19 is narrow, the pressure loss increases, and the refrigerant cannot be charged or flown.
When the horizontal cross-sectional shape of the protrusion is circular, the diameter of the protrusion 19 is preferable. When the protrusion is a polygonal shape or a star shape, the diameter of the circumscribed circle of the protrusion is preferably 10 μm to 5 mm. When the diameter of the protrusion or the circumscribed circle is less than 10 μm, the wear of the protrusion is great, and the effect cannot be exhibited over a long period of time, and when it exceeds 5 mm, cooling cannot be performed uniformly.
As for the height of the projection part 19, it is desirable that they are 5 micrometers-1 mm. If the height of the protrusion is less than 5 μm, the gap between the molding material and the molding material is too small, so that it is difficult to circulate the refrigerant between the mold and the molding material, and if it exceeds 1 mm, the gap becomes excessive. The amount of processing increases and is not economical.

The protrusion 19 can be formed by electrolytic processing, chemical etching, electric discharge processing, plating, or the like.
In chemical etching, a visible light curable photosensitive resin is applied to the mold surface, dried, then covered with a mask that blocks visible light, irradiated with visible light, the irradiated part is cured, and a resin other than the cured part is applied. This is a method of removing with an organic solvent. For example, the mold surface may be immersed in an etching solution such as a sodium chloride aqueous solution for about 1 to 30 minutes and etched. The diameter or pitch of the protrusions can be appropriately selected depending on the shape of the mask that blocks visible light, and the height of the protrusions can be appropriately adjusted depending on the etching time.
Electric discharge machining is a machining method in which a copper electrode having a concave portion in which a target protrusion shape is inverted as a surface pattern is placed facing a mold, a current peak value and a pulse width are changed, and a DC pulse current is passed. . A preferable current value is 2 to 100 A, a pulse width is 2 to 1000 μsec, and the current value may be appropriately adjusted according to the mold material and the desired protrusion shape.
In the case of the plating method, in order to make the diameter of the hemispherical protrusion 10 μm or more, the thickness of the plating is preferably 10 μm or more, and the upper limit is preferably 80 μm or less in order to prevent peeling. The plating layer can be formed at a predetermined bath temperature and current density after alkaline degreasing and electrolytic etching in which a mold is used as an anode in a plating solution. In the case of chromium plating, the current density is about 1 to 200 A / dm ^{2 in the} chromium plating solution, and the bath temperature is about 30 to 60 ° C. In the case of NiW plating, the current density is 1 to 100 A / dm ^{2 in the} NiW plating solution. When the bath temperature is about 30 to 80 ° C., a plating layer having a thickness of 10 to 80 μm can be provided. In order to form a plating layer having a hemispherical protrusion shape, for example, after increasing the current density stepwise, plating may be performed at a constant current density.

(4) Next, the control device 23 that controls at least one of the on-off valve 14, the flow rate adjustment valve 15 and the pressure adjustment valve 16 provided in the refrigerant supply pipe 13 will be described.
The control device 23 is not particularly limited as long as it can control the opening / closing of the on / off valve 14, the flow rate adjusting valve 15 and the pressure adjusting valve 16 provided in the refrigerant supply pipe 13, and can be mechanical or electronic. Regardless of the target means, or a means in which these are combined. For example, by employing a relay switch for these valve mechanisms and controlling the opening and closing (on / off) of the relay switch by a computer (computer), the refrigerant discharge from the refrigerant discharge port 12 communicating with the refrigerant supply pipe 13 As a result, the heat transfer coefficient α at the refrigerant discharge port 12 can be adjusted.

Further, since it is desirable to synchronize the refrigerant discharge timing from the refrigerant discharge port 12 with the punch push-in amount (also referred to as stroke position), measurement data indicating the punch push-in amount or a signal corresponding thereto is input to the control device 23. It is desirable to do. Thereby, it is possible to control the on-off valve 14, the flow rate adjustment valve 15, and the pressure adjustment valve 16 provided in the refrigerant supply pipe 13 in synchronization with the punch push-in amount, and communicate with the refrigerant supply pipe 13. The refrigerant discharge from the refrigerant discharge port 12 can be synchronized with the punch push-in amount.
In the case of forming a columnar press product, the formability is improved by making the refrigerant discharge at the plurality of refrigerant discharge ports 12 in the positional relationship where the punch push-in amount is the same, in this case, It is desirable to make the control of the on-off valves and the like of the refrigerant supply pipe 13 communicating with the plurality of refrigerant discharge ports 12 in the positional relationship where the punch push-in amount is the same.

As the refrigerant used in the hot press molding method according to the present invention, water, polyhydric alcohols, polyhydric alcohol aqueous solution, polyglycol, mineral oil having a flash point of 120 ° C. or higher, synthetic ester, from flame retardancy and corrosiveness , Silicone oil, fluorine oil, grease having a dropping point of 120 ° C. or higher, mineral oil, and water emulsion in which a surfactant is blended with a synthetic ester, or a mixture thereof may be used.
The refrigerant may be liquid or gas. When a gas is used as the refrigerant, the heat transfer coefficient is low, so that it is limited to a case where the processing is not relatively severe, or a case where the martensite transformation or the bainite transformation is not performed. Also, it is desirable to use nitrogen, CO ₂ , or inert gas with low activity in order to avoid surface oxidation. Further, when the refrigerant is a gas, it does not remain attached to the molded product or the hot press molding apparatus, so that there is an effect that unnecessary dirt and rust are hardly generated.

Another problem to be solved by the present invention is that the metal plate 1 heated by the heating device 51 such as a heating furnace is transported to the cooling device 52 such as a cooling tank by the transport device 30 including the hand portion 35 that holds the metal plate material 1. In the heat treatment of a metal plate material that is cooled by a predetermined cooling means in the cooling device to obtain a quenched metal plate material, similarly to the hot press described above, the temperature unevenness occurs in the metal plate material during conveyance. In addition, there is a problem that the hardened hardness is too high and machining such as post-processing becomes difficult. Therefore, the hardened hardness of each part of the metal plate material can be set arbitrarily. An object of the present invention is to provide a heat treatment method and apparatus for a metal plate that can be performed.
For this reason, also in the heat processing method of the metal plate material which concerns on this invention, temperature control of each part of a metal plate material is actively performed, conveying the metal plate material 1, similarly to the hot press molding method which concerns on this invention. Specifically, as shown in FIG. 10, a predetermined part of the metal plate material, for example, a part subjected to machining after the quenching process, using the conveying device 30 constituting the hot press forming apparatus 2 according to the present invention. The metal plate 1 is held and conveyed so as to be in contact with the hand part 35 of the conveying device 30.

If transported in this way, the temperature of the part subjected to the machining, that is, the temperature of the contact part is lower than the temperature of the other part by contact heat removal, which corresponds to lowering the quenching start temperature of the contact part, Thereby, a metal plate material with different quenching hardness can be obtained at the contact portion with the hand portion and other portions, and post-processing at the portion can be easily performed.
Moreover, in order to solve the problem of post-processing by the conventional method, a processing step for partially changing the quenching hardness of the metal plate material after the conveyance is necessary. Therefore, the processing step can be omitted or the processing time can be shortened, and the productivity can be improved.

In addition, if the hand portion 35 is configured by a suction pad or a clamp, it becomes easy to bring the hand portion into contact with a predetermined portion of the metal plate material, for example, a portion subjected to machining, or only to a portion subjected to machining. It becomes easy to contact the hand part, and machining at the contact portion can be easily performed.
Furthermore, if the hand part 35 is constituted by a suction pad or clamp provided with either one or both of the heating means 42 and the cooling means 43, the temperature of the contact portion is reduced by contact heat removal or cooling by the cooling means 43 and heating means. Since it can control by either one or both of the temperature rising by 42, the quenching hardness of a contact part can be set arbitrarily.

The metal plate material 1 used in the heat treatment method for a metal plate material according to the present invention can be applied to any steel plate such as an Al-plated steel plate, a Zn-plated steel plate, a high-strength steel plate, and ordinary steel. In addition, a steel plate that undergoes martensitic transformation or bainite transformation can be increased in strength by quenching, so that a steel plate that undergoes martensitic transformation or bainite transformation is desirable. It is not always necessary to transform at the time of charging into the cooling tank or at the time of quenching such as spray quenching, and it may be transformed after the quenching.
The method of heating the metal plate 1 is not particularly limited, and any method that can heat the metal plate 1 to the A1 transformation point or higher, heating in an electric furnace, gas furnace, flame heating, current heating, high frequency Any method such as heating or induction heating may be used.

Next, an embodiment of the present invention will be described. The conditions of the present embodiment are one condition adopted for demonstrating the feasibility and remarkable effects of the present invention, and the present invention satisfies this one condition. It is not limited.
The conditions and results of the examples are shown in Table 1. In the present embodiment, the metal plate material uniformly heated in the heating furnace is conveyed by the conveying device having the suction pad shown in FIGS. 2 and 3, and the hot press molding device 2 shown in FIG. 11 shows an example in which the cylindrical drawn product shown in b) is molded, and the material to be molded is heated to 900 ° C. (holding time 5 minutes) in a heating furnace, and the plate thickness shown in FIG. A 0.2% C steel plate having a radius of 6 mm and a radius of 140 mm (equivalent to an initial breaking strength of 500 MPa) was used. The press-molded product 60 includes a top portion 61, a vertical wall portion 62, and a flange portion 63, and the height of the vertical wall portion 62 is 20 mm.

The die uses a die 3 and a plate retainer 4 with a refrigerant discharge function. The die 3 has a vertical wall portion and a bottom portion, and the plate retainer 4 has a hole diameter of 2 mm and a pitch of 5 mm evenly at the top. The arranged refrigerant discharge port 12 is formed.
Further, on the mold forming surfaces of Invention Examples 2 to 4, a protrusion 19 having an area ratio of 50%, a height of 1 mm, a diameter of 2 mm, a horizontal cross-sectional shape that is circular, and a vertical cross-sectional shape that is rectangular is formed. Yes. The punch 4 had a diameter of 70 mm and the molding speed was 10 mm / sec.
Regarding the refrigerant discharge capacity, the valve is adjusted so that the heat transfer coefficient α is either 1000 or 3000 kcal / m ² hr ° C. Note that the α heat transfer coefficient of the case without refrigerant discharge, if the mold surface does not form a protrusion 19 1000kcal ^{/ m} 2 hr ℃, when formed is 200kcal ^{/ m} 2 hr ℃.
A radiation thermometer was used to measure the temperature of each part of the steel sheet, and press forming was started immediately after measuring the A to C parts in FIG. In Table 1, temperatures other than A part are not shown, but temperatures of B and C parts were 800 ° C. immediately before the start of press molding.

First, about the comparative example, the heating means provided in the suction pad, specifically, the A part which is a contact portion with the pad part was kept at the same temperature as the B part and C part which are the peripheral parts by an electric heater. As for Comparative Example 1, it was possible to obtain a molded product in which the strength in the A to C portions, that is, the strength of the top portion 61, the vertical wall portion 62, and the flange portion 63 was uniform.
However, in Comparative Example 1, no protrusion is formed on the mold forming surface, and the refrigerant discharge, which is one of the features according to the present invention, is not performed. Also, the pass rate could not satisfy 80%, and the moldability could not be satisfied.
On the other hand, in Invention Example 1 in which the temperature of part A was set to 600 ° C. by contact heat removal with the suction pad in the transport stage, the moldability and strength were improved despite the fact that the refrigerant was not discharged at the bottom dead center. A satisfactory press-formed product could be obtained.
In addition, in Example 2 in which the temperature of part A was set to 600 ° C. by heat removal from the suction pad in the conveying stage and the refrigerant was discharged at the bottom dead center, the bottom dead center retention time was short, and the moldability, strength and It was confirmed that productivity could be satisfied.
Further, Invention Example 3 is one in which the cooling rate is controlled to be different between the vertical wall portion and the other portions, but it is confirmed that the press-formed product 60 having different strengths can be obtained in each part of the molded product also by this method. I was able to.
Similarly, Invention Example 4 is such that the cooling start temperature is controlled to be different depending on the heat removal from the suction pad in the conveying stage, but also by this method, the press-formed product 60 having different strengths in each part of the molded product is obtained. I was able to confirm that

It is an example of the CCT curve of carbon steel which shows that the structure of a steel plate can be controlled by controlling the cooling start temperature and cooling rate of a steel plate. It is a schematic explanatory drawing of the hot press molding apparatus which concerns on this invention. It is explanatory drawing which shows an example of the conveying apparatus which concerns on this invention, (a) is a figure which shows the case where a hand part is comprised with the suction pad, (b) is a figure which shows the temperature distribution of the metal plate material after conveyance, (c) ) Is a diagram showing a distribution of quenching hardness of a press-formed product, and (d) is a cross-sectional view of a suction pad provided with both heating means and cooling means. It is explanatory drawing which shows another example of the conveying apparatus which concerns on this invention, (a) is a figure which shows the case where a hand part is comprised by a clamp, (b) is a figure which shows the temperature distribution of the metal plate material after conveyance, ( c) is a diagram showing a distribution of quenching hardness of a press-formed product, and (d) is a sectional view of a clamp provided with both a heating means and a cooling means. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the metal mold | die which comprises the hot press molding apparatus which concerns on this invention, (a) is the figure which described the die holder and the punch holder, (b) is a die holder in order to clarify the structure of an apparatus. It is the figure which abbreviate | omitted and described the punch holder. It is explanatory drawing which shows the metal mold | die which has the refrigerant | coolant discharge function which concerns on this invention, and is sectional drawing at the time of providing the said function in the punch. It is explanatory drawing which shows an example of the metal mold | die which concerns on this invention, and is a figure which shows the surface of the metal mold | die which formed the refrigerant | coolant discharge port, the refrigerant | coolant collection port, and the projection part. It is sectional drawing which shows an example of the metal mold | die which concerns on this invention, and is a figure which shows the cross section of the metal mold | die which formed the refrigerant | coolant discharge port, the refrigerant | coolant collection port, and the projection part. It is sectional drawing which shows another example of the metal mold | die which concerns on this invention, and is a figure which shows the cross section of the metal mold | die which formed the refrigerant | coolant discharge port, the refrigerant | coolant collection port, and the projection part. It is a schematic explanatory drawing of the heat processing apparatus of the metal plate material which concerns on this invention. It is explanatory drawing which shows an example of a press molded product, (a) is explanatory drawing which shows a to-be-molded material, (b) shows the molded product by a cylindrical aperture drawing. It is a schematic diagram which shows one Embodiment of the hot press molding method which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal plate material 2 Hot press molding apparatus 3 Dies 4 Punch 5 Pad 6 Board presser 7 Die base (upper mold) 8 Die base (lower mold)
DESCRIPTION OF SYMBOLS 9 Die holder 10 Punch holder 11 Die set 12 Refrigerant discharge port 13 Refrigerant supply pipe 14 On-off valve 15 Flow rate adjustment valve 16 Pressure adjustment valve 17 Refrigerant recovery port 18 Refrigerant recovery pipe 19 Protrusion part 20 Core 21 Seal 22 Mold whole cooling part 23 Control device 30 Transport device 31 Base 32 Arm 33 Vacuum generator 34 Vacuum hose 35 Hand part 36 Frame 37 Suction pad 38 Conduit 39 Skirt part 40 Pad part 41 Sealing material 42 Heating means 43 Cooling means 44 Clamp 45 Upper clamp plate 46 Lower part Clamp plate 47 Air cylinder 48 Guide 49 Claw part 50 Contact part 51 Heating device 52 Cooling device 53 Coolant liquid 54 Screw 55 for fixing the sealing material Vacuum or reduced pressure space 60 Press-formed product 61 Top part 62 Vertical wall part 63 Flange part 64 Temperature control Area

Claims (24)

In a hot press molding method in which a metal plate material heated by a heating device is conveyed to a mold constituting a press molding apparatus by a conveyance device having a hand unit that holds the metal plate material, and the metal plate material is molded using the mold. The metal plate material is held and conveyed so that a predetermined part of the metal plate material is in contact with the hand part, and the temperature of the part in contact with the hand part is made different from the temperature of other parts by contact heat removal, A hot press molding method characterized by starting press molding.
In a hot press molding method in which a metal plate material heated by a heating device is conveyed to a mold constituting a press molding apparatus by a conveyance device having a hand unit that holds the metal plate material, and the metal plate material is molded using the mold. The metal plate material is held and transported so that the predetermined part of the metal plate material is in contact with the hand part, and the temperature of the part in contact with the hand part is made different from the temperature of the other part by contact heat removal and transported. After the metal plate material is set in the mold, it is provided on the mold surface by refrigerant discharge from a plurality of refrigerant discharge ports provided on the mold surface in at least one state before molding, during molding, or after molding. A hot press forming method characterized in that the temperature of an arbitrary part of the metal plate material is controlled by refrigerant discharge from a plurality of refrigerant discharge ports and refrigerant recovery from the refrigerant recovery port.
The hand portion is constituted by a suction pad or a clamp provided with either one or both of a heating means and a cooling means, and when the metal plate material is conveyed by the suction effect of the suction pad or sandwiched by the clamp, the hand 2. The hot press forming method according to claim 1, wherein the temperature of the portion in contact with the section is controlled by one or both of contact heat removal, cooling by a cooling means, and temperature rise by a heating means.
The hand portion is constituted by a suction pad or a clamp provided with either one or both of a heating means and a cooling means, and when the metal plate material is conveyed by the suction effect of the suction pad or sandwiched by the clamp, the hand 3. The hot press forming method according to claim 2, wherein the temperature of the portion in contact with the section is controlled by one or both of contact heat removal, cooling by a cooling means, and temperature rise by a heating means.
The refrigerant discharge is controlled by one or more parameters selected from the refrigerant discharge amount, discharge flow rate, discharge pressure, discharge time, and discharge timing, and for each refrigerant discharge port or from a plurality of refrigerant discharge ports 5. The hot press forming method according to claim 2, wherein the refrigerant discharge is grouped and controlled for each group.
The predetermined part of the metal plate material is a part that undergoes machining after press molding, or a part that receives one or both of draw molding and foam molding during press molding, and the temperature of the part that contacts the hand part The hot press according to any one of claims 1 to 5, wherein the hot press is set to a temperature corresponding to the strength of a part subjected to machining or a temperature corresponding to a degree of processing of draw molding or foam molding. Molding method.
The hot press forming method according to claim 1, wherein the metal plate is a steel plate.
The hot press forming method according to claim 7, wherein the steel sheet is a steel sheet that undergoes martensitic transformation or bainite transformation.
In the metal plate material heat treatment method, the metal plate material heated by the heating device is conveyed to a cooling device by a conveying device having a hand unit that holds the metal plate material, and is cooled by a predetermined cooling means in the cooling device and quenched. By holding and transporting the metal plate so that the predetermined part of the hand part comes into contact with the hand part, the temperature of the part in contact with the hand part is made different from the temperature of the other part by contact heat removal. A heat treatment method for a metal plate material, wherein the quenching hardness of the metal plate material is made different between the contact portion and the other portion.
The hand part is constituted by a suction pad or a clamp provided with either one or both of a heating means and a cooling means, and the hand is held by the suction effect of the suction pad or when the metal plate material is conveyed by being clamped by the clamp. By arbitrarily controlling the temperature of the part in contact with the part by either one or both of contact heat removal or cooling by the cooling means and temperature rise by the heating means, the quenching hardness of the part in contact with the hand part is arbitrarily set The metal plate material heat treatment method according to claim 9, wherein
The predetermined part of the metal plate material is a part subjected to machining after quenching, and the temperature of the part in contact with the hand part is set to a temperature according to the strength of the part subjected to machining. The heat processing method of the metal plate material of Claim 9 or 10.
The method for heat treatment of a metal plate material according to any one of claims 9 to 11, wherein the metal plate material is a steel plate.
The method for heat treatment of a metal sheet according to claim 12, wherein the steel sheet is a steel sheet that undergoes martensitic transformation or bainite transformation.
In a hot press forming apparatus comprising a heating device that heats a metal plate material, a transfer device that transfers the heated metal plate material, and a mold that press-forms the transferred metal plate material, the transfer device includes a predetermined metal plate material A hot press molding apparatus comprising: a hand part that can contact a part and that makes the temperature of the part to be contacted different from the temperature of another part by contact heat removal.
The hot section according to claim 14, wherein the hand unit is configured by a suction pad or a clamp including one or both of a heating unit that raises the temperature of the metal plate and a cooling unit that cools the metal plate. Press molding equipment.
The said hand part has a structure which can isolate | separate into the site | part which contacts a metal plate material, and a site | part other than that, At least 1 of the shape of the site | part which contacts a metal plate material, a magnitude | size, and a material can be changed, Item 16. The hot press molding apparatus according to Item 14 or 15.
The predetermined part of the metal plate material is a part that undergoes machining after press molding, or a part that receives either or both of draw molding and foam molding during press molding. The hot press molding apparatus of any one of Claims.
The mold is provided with a refrigerant supply pipe having a plurality of refrigerant discharge ports on the surface, communicating with each refrigerant discharge port inside, and having at least one of an on-off valve, a flow rate adjustment valve, and a pressure adjustment valve. It is a metal mold | die, The hot press molding apparatus of any one of Claims 14-17 characterized by the above-mentioned.
The die according to any one of claims 14 to 18, wherein the die is a die provided with a plurality of refrigerant recovery ports on the surface and provided with a refrigerant recovery pipe communicating with each of the refrigerant recovery ports. The hot press molding apparatus as described.
The die according to any one of claims 14 to 19, wherein the mold has a plurality of protrusions having an area ratio of 1 to 90%, a diameter or a circumscribed circle diameter of 10 µm to 5 mm, and a height of 5 µm to 1 mm on the surface. The hot press molding apparatus according to claim 1.
In a heat treatment apparatus for a metal plate material comprising a heating device for heating a metal plate material, a conveyance device for conveying the heated metal plate material, and a cooling device for quenching the conveyed metal plate material, the conveying device is a predetermined part of the metal plate material A heat treatment apparatus for a metal plate material, comprising: a hand portion that can come into contact with the contact portion and that makes the temperature of the contact portion different from the temperature of other portions by contact heat removal.
The metal plate material according to claim 21, wherein the hand portion is constituted by a suction pad or a clamp provided with either or both of a heating means for raising the temperature of the metal plate material and a cooling means for cooling the metal plate material. Heat treatment equipment.
The said hand part has a structure which can isolate | separate into the site | part which contacts a metal plate material, and a site | part other than that, At least 1 of the shape of the site | part which contacts a metal plate material, a magnitude | size, and a material can be changed, It is characterized by the above-mentioned. Item 22. A heat treatment apparatus for a metal sheet according to Item 21 or 22.
The heat treatment apparatus for metal plate according to any one of claims 21 to 23, wherein the predetermined part of the metal plate material is a part subjected to machining after quenching.

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