JP4135397B2 - Method and apparatus for quenching pressed parts - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a method for quenching a pressed part for press-molding a heated steel plate and a quenching apparatus.In placeIn particular, a method of quenching and quenching of press parts that can be partially post-processedIn placeIt is related.
[0002]
[Prior art]
Conventionally, steel plates (panel materials) are assembled and formed by welding or the like. For example, as a method for improving the strength of a steel plate to reduce the weight of a vehicle body or the like, a conventional method using a high-strength steel plate (high-tensile steel plate) is used. Thus, it has been proposed to rapidly cool and quench a heated steel sheet by press forming.
[0003]
In this forming method, a steel sheet is heated to around 1000 degrees Celsius, and put into a press mold to press form a steel sheet of about 800 degrees Celsius. The steel sheet to be press-formed has a low material strength due to high temperature, and deforms straight along the forming die, thereby improving the dimensional accuracy of the formed product. Further, when the steel sheet is sandwiched between the forming dies, the forming dies are deprived of heat and rapidly cooled and quenched, so that the strength of the base material of the formed product can be greatly improved. Since the molded product is formed in a quenched state, there are very few dimensional accuracy defects such as a spring back.
[0004]
[Problems to be solved by the invention]
However, the molded product of the above conventional example has the following problems because the hardness is increased by quenching with a press mold.
[0005]
That is, the hardness of the surface of the molded product is increased by quenching by rapid cooling, and drilling and trimming are difficult due to an increase in shear resistance. Moreover, even if it can process, there is an influence of tool breakage and tool wear.
[0006]
Also, if piercing or other processing is performed before the hardness is increased by quenching due to quenching, and then press molding is performed, the position of the hole may be displaced due to movement of the material that occurs during molding, and the product may not be established due to the error. There is. For this reason, the parts that may be processed before quenching (error is allowed) are limited.
[0007]
  Accordingly, the present invention has been made in view of the above problems, and a quenching method and a quenching device for a pressed part that can be partially post-processed.PlaceThe purpose is to provide.
[0008]
[Means for Solving the Problems]
  The first invention isThe quenching hardness was changed for each part by changing the cooling rate for each part of the molded product shape by the mold simultaneously with press forming of the heated steel plate.It is a method of quenching a pressed part to obtain a molded product,The forming die is provided with a heating medium that can be projected and retracted from the forming surface and is urged to be projected, and prior to forming the heated steel plate by the forming die, the heating medium is brought into contact with the heated steel plate and the temperature of the heated steel plate at the contact site By suppressing the decrease and pressing the heated steel sheet by retreating the heating medium to the molding surface while maintaining the contact state as the heated steel sheet is molded by the molding surface, The cooling rate of the was changed.
[0009]
  According to a third aspect of the present invention, there is provided a press part for obtaining a molded product in which the quenching hardness is changed for each part by changing the cooling rate for each part of the molded product shape by the mold simultaneously with press molding of the heated steel plate. It is a quenching device, and the mold temperature for each molded product shape part of the molding die is arranged so as to be able to protrude from the molding surface and is projected and biased, and comes into contact with the heated steel plate before contacting the molding surface. By changing the heating rate of the heating medium arranged so as to be accommodated on the molding surface as it is molded, the cooling rate for each part of the molded product shape is varied.I did it.
[0010]
【The invention's effect】
  Therefore,In the first and third inventionsSince the quenching hardness of the molded product can be selected for each part by changing the cooling rate for each part, the part can be easily processed by reducing the quenching hardness of the part requiring processing.
[0011]
  Moreover, since the site | part which reduced quenching hardness becomes so much toughness, the intensity | strength and toughness of a molded product can be controlled corresponding to the request | requirement for every site | part.
  Also, because the cooling rate of the steel sheet is varied by changing the mold temperature in advance for each part of the molded product shape, the low temperature part where the mold temperature is low has high quenching hardness, and the high temperature part where the mold temperature is high is quenching hardness. Can be set low.
  And since the said mold temperature is changed by heating with the heat generating body which is a heating medium, if the position of a heat generating body is changed, distribution of quenching hardness can be changed without changing the shaping | molding surface of a shaping | molding die.
  In addition, the heating element can be protruded and projected from the forming surface and is urged to project, and is brought into contact with the steel plate before being brought into contact with the forming surface, so that the steel plate is accommodated in the forming surface as it is formed by the forming surface. The heating element can contact the steel plate to adjust the temperature of the steel plate with higher accuracy, and the material composition of the pressed part can be easily controlled.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, a method of quenching a press part and a quenching apparatus according to the present inventionPlaceThe embodiment to be realizedeachThis will be described based on the embodiment.
[0015]
  1 to 4 are,Quenching method and quenching of less partsReference example 1FIG. 1 shows a press part press-formed from a steel plate, FIG. 2 shows a press-forming die for press-forming the press part of FIG. 1, FIG. 3 shows details of the main part of the steel plate and the press-forming die, Reference numeral 4 denotes the hardness state of the rigidity-decreasing portion.
[0016]
The press part 1 shown in FIG. 1 has a hat-shaped cross section. For example, in the vehicle body structure shown in FIG. 20, the side member SM that forms the engine compartment, the pillar PR that forms the passenger compartment, or the side sill Applies to outer SO etc. These panel parts contribute to a relatively large improvement in the rigidity of the vehicle body by improving their rigidity.
[0017]
For this reason, the press part 1 is heated to about 1000 ° C. at the time of press forming and is set to a press mold at about 800 ° C., and the heat of the steel plate is rapidly taken away by the mold by press forming. Cool quickly. The press-molded press part 1 is entirely quenched (referred to as quenching part A), and the strength of the base material is significantly increased. The steel plate material used is a cold-rolled steel plate material having a slightly larger amount of carbon (C) (about 0.2 to 0.24%) and an alloy component or the like added thereto, for example, SPC20CB, in order to improve hardenability. Use improved materials.
[0018]
By the way, there are parts in the press part 1 that do not require design-level strength and parts that are post-processed such as drilling (piercing) and cutting (trim). It is necessary to reduce the hole and to enable drilling and cutting. The portion surrounded by the oblique lines in FIG. 1 is the rigidity reduction portion 2 (that is, the hardening hardness is relatively low at this portion). Hereinafter, a press mold for forming the press part 1 including the quenched portion A and the rigidity reduced portion 2 will be described.
[0019]
FIG. 2 shows a cross-sectional view of a press mold 5 for molding the press part 1, and is a general combination of a die 6, a punch 7 and a blank holder 8. On the surface of the die 6 and the punch 7 facing the reduced rigidity portion 2, depressions 6A and 7A are formed over the range of the width Wd so that the die 6 and the punch 7 do not contact the steel plate W to be formed. To do. As shown in FIG. 3, the width Wd of the recesses 6A and 7A is slightly larger than the width Wp of the rigidity-decreasing portion 2, that is, the length that is cooled by heat transfer / heat absorption through the steel plate W itself to the forming die 5. It is formed larger by X.
[0020]
In the press mold 5 having the above configuration, the steel sheet W is heated to about 1000 ° C. and is about 800 ° C. when it is put into the mold 5, and the steel sheet W in a state where the material strength is reduced due to high temperature is die-molded. 6 is held between the holding part 6B and the blank holder 8 and press-molded by the punch 7. The steel plate W is deformed straight along the forming die 5 in the quenched portion A excluding the rigidity-decreasing portion 2 due to the punch 7 and the recesses 6A and 7A of the die 6, and the molded product 1 has high dimensional accuracy. In addition, the steel sheet W is sandwiched between the molds 5 so that the mold 5 is deprived of heat and rapidly cooled and quenched, so that the strength of the base material of the molded product 1 can be greatly improved. Since the molded product 1 is formed in a quenched state, there are very few dimensional accuracy defects such as a spring back.
[0021]
On the other hand, the steel plate W of the rigidity-reduced portion 2 facing the recesses 6A and 7A of the punch 7 and the die 6 is not in contact with the punch 7 and the die 6, and is not deformed or rapidly cooled by these forming dies 5, that is, cooled. The rigidity lowering portion 2 is configured such that the speed is low and the quenching hardness, that is, the strength / hardness is lower than the other portions. According to FIG. 3 which shows the contact state of the forming die 5 and the steel plate WS, the punch 7 and the die 6 and the steel plate W have the width Wd obtained by adding the width of the boundary region to the width Wp of the rigidity reduction portion 2 and the die 6. And the width | variety of the hollows 6A and 7A of the punch 7 is formed. FIG. 4 shows a change in hardness (Vickers hardness HV) of the molded product 1 with the distance from the edge of the recesses 6A and 7A (the boundary region X) as the horizontal axis and the hardness (HV) of the molded product 1 as the vertical axis. Is shown. According to this, the hardness is over 500 (HV) at a position of 5 mm close to the edges of the recesses 6A and 7A, but the hardness is reduced to about 420 (HV) at a position 15 mm away from the edge. Therefore, it is obtained from experimental data that the hardness in the range Wp can be lowered by securing a depression in a range Wd that is at least 15 mm larger on one side than the range WP in which the quenching hardness is desired to be kept low during molding. For example, when it is desired to make a portion having a width of 30 mm low, it is necessary to provide recesses 6A and 7A in the press mold 5 with a width of at least 15 mm on one side, that is, a width of 60 mm. The depths of the recesses 6A and 7A need not be in contact with the steel plate W, and may be a depth of several mm. Further, it is desirable that the edges of the recesses 6A and 7A should be gradually deepened so as to smoothly connect the boundaries, rather than having steps.
[0022]
In addition, about 30 seconds after the press forming is completed, the temperature data of the steel plate W portion facing the recesses 6A and 7A and the steel plate W portion contacting the punch 7 and the die 6 are taken to obtain an average value of several values. In the portion facing the recesses 6A and 7A, the temperature was about 130 ° C., whereas the portion in contact with the mold 5 was about 70 ° C. From this, it can be understood that quenching has progressed in the contact portion with the mold 5, but quenching has not progressed relatively in the non-contact recesses 6A and 7A.
[0023]
Therefore, even if the heated steel sheet W is press-molded by the press mold 5 and quenched, the hardness of the part to be trimmed or pierced can be made lower than that of the general part, and the processing force can be reduced and the tool wear can be reduced. Prevention can be expected.
[0024]
In addition, at the time of press molding by the press mold 5, there is a concern that the heated steel plate W is first sandwiched between the blank holder 8 and the holder portion 6B of the die 6 and rapidly cooled and quenched by both of them. In order to suppress this rapid cooling, when a heat insulating member or a member having low thermal conductivity is inserted in a portion of the blank holder 8 and the holder 6B of the die 6 that contacts the steel plate W, the subsequent press forming of the steel plate W It is effective in the sense that it does not increase the hardness. In addition, it is most effective to provide a heat insulating member or a member having low thermal conductivity in a portion that directly contacts the steel plate W, but the steel plate W is brought into contact with a metal having excellent wear resistance and corrosion resistance. You may do it.
[0025]
  Also, aboveReference example 1However, although not illustrated, for example, the depressions 6A and 7A are formed by a large number of dimples to reduce the heat transfer area, You may make it make a cooling rate slow with respect to the other general cross section of a shaping | molding surface. In this case, since the rigidity-decreasing portion 2 is also press-molded by the intermittent molding surface by dimples, the shape accuracy of the rigidity-decreasing portion 2 can be further improved.
[0026]
  Reference Example 1Can produce the effects described below.
[0027]
(A) The charged heated steel sheet W is cooled by the mold 5 at different cooling rates for each shape part of the molded product, and the quenching hardness of the part that needs to be processed to change the quenching hardness obtained for each part. The rigidity reduced portion 2 can be obtained by reducing the height, and the processing of the portion can be facilitated.
[0028]
(A) Moreover, since the rigidity reduction part 2 as a site | part which reduced quenching hardness becomes high so much, the intensity | strength and toughness of the molded article 1 can be controlled corresponding to the request | requirement for every site | part.
[0029]
(C) Since the cooling rate for each part is made different by changing the contact area per unit area between the forming surface shape part of the mold 5 and the steel sheet W, the part with a large contact area is contacted because the cooling rate is fast. The quenching hardness can be increased as compared with a portion having a small area.
[0030]
(D) Since the contact area per unit area is formed by the presence or absence of recesses 6A and 7A provided on the opposing molding surface of the mold 5, it can be formed simply by providing the recesses 6A and 7A on the molding surface of the mold 5; The present invention can be applied to a portion where a highly accurate transfer to a press part having a molding surface shape of the molding die 5 is not so necessary.
[0031]
(E) When the contact area per unit area is changed by a plurality of depressions provided on the molding surface of the mold 5, that is, the density of the dimples, molding is performed with higher accuracy than the pressed part 1 using the depressions 6A and 7A. The molding surface shape of the mold 5 can be transferred to the press part 1 with high accuracy.
[0032]
  next,Quenching method and quenching of less partsPlaceRealizeAbout Reference Example 2explain.
[0033]
  FIG.,Quenching method and quenching of less partsReference example 2Instead of forming the recesses 6A and 7A in the punch 7 and the die 6 so as not to come into contact with the steel plate W, the mold material of the portion of the punch 7 and the die 6 in contact with the steel plate W Is formed of a material having a low thermal conductivity to form the reduced-rigidity portion 2.
[0034]
As shown in FIG. 5, a mold material 7C in a range corresponding to the rigidity reduced portion 2 of the punch 7 that is usually formed of a casting or a steel material is formed of a material having a low thermal conductivity such as a stainless steel material. Although not shown, the die 6C of the die 6 is similarly formed of a material having a low thermal conductivity such as stainless steel in a range corresponding to the rigidity reduction portion 2. In the example of the punch 7 shown in FIG. 5, the mold material 7 </ b> C having a low thermal conductivity such as stainless steel is fixed by inserting a trapezoidal block-shaped mold material 7 </ b> C into a block made of a material that is the basis of the punch 7 (insert structure). ing. Also on the die 6 side, the mold material 6C having a low thermal conductivity including the range corresponding to the mold material 7C formed of the material having a low thermal conductivity of the punch 7 is fitted into a block shape (insert structure) and fixed. In addition, the range in which the mold materials 6C and 7C having low thermal conductivity are arranged is formed to be larger than the range of the rigidity reduction portion 2 by the width of the boundary region X that conducts heat by the steel plate W itself. Further, the blank holder 8 and the holder portion 6B of the die 6 have the structure described in the first embodiment. In addition, although stainless steel was mentioned as a material with low thermal conductivity, other metals, ceramics, resins, and the like may be used as long as they satisfy heat resistance, corrosion resistance, and mold material conditions.
[0035]
FIG. 6 is a graph showing the change in hardness of the obtained molded product with the horizontal axis representing the thermal conductivity of the mold members 6C and 7C and the vertical axis representing the hardness (HV). As can be seen from this graph, the hardness of the molded product increases as the thermal conductivity of the mold members 6C and 7C increases, and the hardness of the molded product can decrease as the thermal conductivity decreases.
[0036]
Therefore, by forming the press mold 5 in this way, the molded product portion that is press-molded by the molding surface formed of the material having low thermal conductivity is suppressed from being rapidly cooled, and the quenching effect is alleviated. Let it be a rigidity-decreasing portion 2. On the other hand, a molded product portion that is press-molded by a molding surface formed of a mold material of other general materials can be rapidly cooled to form a quenched portion A that increases the quenching effect and increases its hardness.
[0037]
Moreover, since the steel sheet is formed in contact with both a molding surface formed of a normal material and a molding surface formed of a material with low thermal conductivity, any part of the molded product can be taken. Shape accuracy can be increased.
[0038]
  The aboveReference example 2Explains the formation of the molding surfaces of the mold materials 6C and 7C with a material having low thermal conductivity, but although not shown, for example, a part of the molding surface of the mold material is separated and fixed via a heat insulating material. You may make it do. In this case, since it is thermally floated by the heat insulating material, the temperature of this portion can be maintained higher than that of other mold material portions by heat input from the heated steel plate.
[0039]
  BookReference example 2InReference example 1In addition to the effects (a) and (b), the effects described below can be achieved.
[0040]
(F) Since the cooling rate of the steel plate W is made different by using the mold materials 6C and 7C made of materials having different heat conduction for each molded product shape part of the mold 5, for example, a part requiring high quenching hardness is made of steel or By using a mold material such as a casting, and using a mold material having a low thermal conductivity such as stainless steel in a portion where a low quenching hardness may be used, a change in the quenching hardness can be provided.
[0041]
(G) Since all the forming surfaces of the forming die 5 are in contact with the steel plate W, the shape accuracy of the pressed part 1 can be made high.
[0042]
  (Third embodiment)
  Next, a method for quenching a pressed part and a quenching apparatus according to the present inventionPlaceThe embodiment to be realized1This will be described based on the embodiment.
[0043]
  7 to 12 show a method of quenching a press part and a quenching apparatus according to the present invention.SetFirst1In this embodiment, instead of forming a reduced-rigidity part by not contacting the steel sheet or by using a mold material having low thermal conductivity, the reduced-temperature part is formed by suppressing the temperature decrease of the steel sheet by a heating element. It is what you do.
[0044]
FIG. 7 shows a mold 5 provided with a heating element 10, and in addition to a general mold 5 provided with a die 6, a punch 7, a blank holder 8 and a cushion 9, heat generation protruding into the molding space of the die 6. A body 10 is provided. The heating element 10 is held by a heat insulating material 11, and the heat insulating material 11 is slidably inserted into a guide hole 6D provided in the die 6 in the vertical direction, and an elastic body such as a spring 12 disposed at the bottom of the guide hole 6D. Is biased to protrude. The heating element 10 is constituted by, for example, a heat transfer heater, and is supplied with electric power through a power line 13 passing through a hole 6E extending from the guide hole 6D to the side of the die 6. The temperature of the heating element 10 is set between 250 ° C. and 900 ° C. according to the carbon amount because the quenching effect varies depending on the carbon amount of the steel plate W. The heating element 10 is projected and urged by the elastic body 12, and is positioned so as to project downward from the holder portion 6 </ b> B that holds the steel plate W together with the blank holder 8 of the die 6 when the die 6 is detached from the punch 7. . As the die 6 is overlapped with the punch 7 by clamping, the die 6 is moved back into the guide hole 6D of the die 6 when the press molding is completed.
[0045]
FIG. 8A to FIG. 9B show the press molding process in the present embodiment, which will be described below.
[0046]
First, the steel sheet W is heated to about 1000 ° C. by the heating furnace 15 shown in FIG. 8 (A), and is put into the press-molding die 5 which is opened as shown in FIG. It is placed on the holder 8.
[0047]
Next, as shown in FIG. 9A, when the die 6 of the mold 5 is lowered, first, the heating element 10 held by the heat insulating material 11 comes into contact with the steel plate W. Since the heating element 10 is maintained at the set temperature, the temperature of the portion of the steel plate W that contacts the heating element 10 is radiated through the punch 7 to the temperature set by the heating element 10, and then the heat is generated. The temperature of the body 10 is maintained.
[0048]
Next, the steel plate W is sandwiched between the holder portion 6B of the die 6 and the blank holder 8, and subsequently the die 6 is lowered, whereby the steel plate W is deformed straight into the forming die 5 and is rapidly cooled from the forming surface. However, the temperature of the steel sheet W at the portion in contact with the heating element 10 is maintained by the heating element 10.
[0049]
Thereafter, when the die 6 is raised and the mold is opened, the blank holder 8 is also lifted, the contact between the molded product 1 and the punch 7 is released, and then the contact between the blank holder 8 and the molded product 1 is released. Even at this time, the molded product 1 and the heating element 10 maintain contact, and the heating element 10 continues to warm the molded product 1. When the molded product 1 is detached from the mold 5, the molded product 1 is air-cooled and gradually cooled.
[0050]
  FIG. 10 shows the temperature change of the steel sheet W in the forming process.ShowIn the general cross-section portion that is the quenching portion A that is quenched by the press mold 5, it is heated in the heating furnace 15 in FIG. At time T4, the steel sheet W is press-formed and rapidly cooled to the time T5 by the forming die 5, and then cooled in the air from the time T5.
[0051]
On the other hand, when the steel sheet W is cooled from the time T2 before the time T4 when the steel sheet W is rapidly cooled by press forming to the time T3 when the temperature of the heat generating body 10 comes into contact with the heat generating body 10 and the mold is opened. The temperature of the heating element 10 is maintained until the time T6 when the heating element 10 after T5 is detached from the molded product 1, and is cooled in the air from the time T6. That is, from the time T3 to the time T6, the temperature of the heating element 10 is maintained and is not rapidly cooled.
[0052]
FIG. 11 shows a perspective view of the molded product 1 by the method of quenching a pressed part having the above configuration. In the molded product 1, by arranging a plurality of heating elements 10, a plurality of the rigidity lowering portions 2 shown by oblique lines can be arranged as shown.
[0053]
FIG. 12 is a comparison of the hardness of the general cross-sectional portion that is the quenched portion A and the rigidity reduced portion 2, and the hardness in the general cross-sectional portion is about 500 (HV), whereas the rigidity reduced portion 2 The hardness is about 400 (HV) and the rigidity is lowered.
[0054]
FIG. 13 shows a modification of the present embodiment, in which a heat insulator 16 is embedded at the tip of the punch 7 facing the heating element 10. The heat insulator 16 sandwiches the steel plate W together with the heating element 10, suppresses the amount of heat that escapes from the punch 7, decreases the cooling rate of the rigidity reduction portion 2, and gradually decreases the temperature. Due to the presence of the heat insulating material 16, the time T3 when the temperature is lowered to the temperature of the heating element 10 in FIG. 10 is delayed, and it is possible to perform cooling while maintaining the temperature of the rigidity reduction portion 2 high correspondingly.
[0055]
In addition, although the said embodiment demonstrated what the heat generating body 10 was formed in the die | dye 6 so that advancement / retraction was possible, although not shown in figure, for example via a heat insulating material so that the shaping | molding surface of a die | dye and / or a punch may be comprised. It may be a fixed heating element. Even in this case, the temperature of the rigidity-decreasing portion decreases as in the case of the other general cross-sectional portions. However, after the temperature decreases to the temperature of the heating element, the temperature can be maintained and quenching due to rapid cooling can be prevented.
[0056]
  In this embodiment,Reference example 1In addition to the effects (a) and (b), the effects described below can be achieved.
[0057]
(H) Since the cooling rate of the steel sheet W is varied by changing the mold temperature in advance for each part of the molded product shape of the mold 5, the low temperature part where the mold temperature is low has high quenching hardness and the high temperature part where the mold temperature is high. Can be set to a low quenching hardness.
[0058]
(K) Since the mold temperature is changed by heating with the heating element 10 as a heating medium, changing the position of the heating element 10 changes the distribution of the quenching hardness without changing the molding surface of the mold 5. be able to.
[0059]
(E) The heating element 10 can be projected and retracted from the forming surface and protruded and urged to come into contact with the steel plate W before being brought into contact with the forming surface and accommodated in the forming surface as the steel plate W is formed by the forming surface. Since it arrange | positions so that the heat generating body 10 may contact the steel plate W, the temperature of the steel plate W can be adjusted more accurately, and control of the material composition of the press part 1 can be performed easily.
[0060]
  next,To realize a quenching method, quenching equipment and press parts for less partsAbout Reference Example 3explain.
[0061]
  14 to 19 are,Method and apparatus for quenching less partsReference example 3In this case, the holes are processed in the press mold instead of being separated from the press mold and processed in another post-process.
[0062]
  Figure 14 shows the bookReference example 3The die 6 is the same as that shown in FIG. 1, in which the lower die is formed by the blank holder 8 and the punch 7 supported by the cushion pin 9, and the upper die is formed by the die 6. The structure is supported by a pressure source 19 such as a rubber or a tanker cylinder, can be moved up and down by a retainer 18 or the like, the structure of a piercing punch 20 disposed through the die 6 in the upper plate 17, and the piercing punch in the punch 7. A configuration in which the button die 21 is disposed corresponding to 20 is newly provided.
[0063]
In this case, the upper plate 17 is lowered by the press machine, and the steel plate W is press-formed by the operations shown in FIGS. 15 to 17, and then the formed product 1 is pierced. Details will be described below.
[0064]
First, as shown in FIG. 15, the upper plate 17, the die 6, and the pressure source 19 are integrally lowered, the holder portion 6 </ b> B of the die 6 contacts the steel plate W, and the blank holder 8. The steel plate W is held.
[0065]
When the upper plate 17 is further lowered, the cushion pressure applied to the cushion pin 9 is smaller than the pressure source 19 of the upper die, so that the blank holder 8 is pushed downward by the die 6 and the steel plate W is moved as shown in FIG. Press molding is performed between the die 6 and the punch 7.
[0066]
Since the die 6 is prevented from further descending with the punch 7 and the steel plate W sandwiched by the press molding, the upper plate 17 compresses the pressure source 19 and lowers the pierce punch 20 as shown in FIG. . The piercing punch 20 pierces the steel plate W with the button die 21.
[0067]
Thereafter, when the upper plate 17 is raised, both the piercing punch 20 and the die 6 are raised, and the machining is completed.
[0068]
In the above operation, the temperature of the steel plate W at the time of piercing is lowered by contact with the punch 7, but since it is at least 500 degrees Celsius, the shear resistance at the time of piercing is reduced. For this reason, tool breakage prevention and tool life extension can be achieved.
[0069]
Then, since processing such as piercing is performed after press forming, the material movement of the steel plate W has been completed, the displacement of the hole position can be avoided, and accurate hole processing becomes possible.
[0070]
FIG. 18 shows a modification of the pierce punch 20. This is proposed in order to fix the steel plate W around the hole by the pad 22 at the time of piercing and to perform piercing with the piercing punch 20 with high accuracy.
[0071]
In FIG. 18, the pierce punch 20 is fixed to a punch retainer 23 fixed to the upper plate 17, and an elastic body 24 such as a cylindrical urethane rubber and a heat insulating material 25 at the tip of the elastic body 24 so as to wrap the pierce punch 20. The cylindrical pad 22 is also fixed via the. When the pad 22 contacts the hot steel plate W, the heat insulating material 25 is disposed to prevent the heat from being transferred to the elastic body 24 and melting the elastic body 24.
[0072]
  19 shows the bookReference exampleThe modified example of the quenching method of press parts of this is shown, and the freedom degree of the piercing | piercing punching timing is further improved. That is, instead of the retainer 18 and the pressure source 19 used to operate the pierce punch 20, the pierce punch 20 is arranged on the upper plate 17 via an actuator 26 such as a cylinder. In this case, the die 6 is fixed directly to the upper plate 17.
[0073]
As the upper plate 17 of the press machine descends, the die 6 blank-holds the steel plate W with the blank holder 8, presses the steel plate W with the punch 7, and the upper plate 17 is at the bottom dead center. Retained.
[0074]
While being held, the piercing punch 20 is extruded by the actuator 26 such as a cylinder to make a hole in the molded product 1.
[0075]
Since the power source is provided separately from the press machine, the timing of piercing can be arbitrarily set, and piercing can be performed at the timing when the steel plate W is lowered to a temperature considered to be optimal. Even in this structure, the hole shape accuracy is improved by using the pierce punch 20 provided with the pad 22 for pressing the steel plate W.
[0076]
  In this reference example 3,Reference example 1In addition to the effects (a) and (b), the effects described below can be achieved.
[0077]
(S) Since the molded product 1 is processed before it is press-molded in the mold 5 and cooled and cured, the material of the molded product 1 can be processed while the material strength is low and the material strength is low. Since the force can be kept low, the machining is easy and the damage to the tool is prevented and the tool life is extended.
[0078]
(F) Since the processing is performed after the press molding, the material of the molded product 1 has been moved, so that the displacement of the hole position or the like due to the processing can be avoided, and the processing with high accuracy is possible.
[0079]
(S) In FIG. 14, since the pierce punch 20 and the button die 21 as the processing device are operated in conjunction with the completion of press forming by the forming die 5, the die 6 can be moved up and down on the upper plate 17 by a retainer 18 or the like. It can be easily applied to a press machine by supporting it through a pressure source 19 such as rubber or a tanker cylinder.
[0080]
(C) In FIG. 19, since the pierce punch 20 as the processing device is operated independently of the press forming by the forming die 5, the material temperature at the time of processing can be arbitrarily selected, and the hole with high accuracy can be selected. Processing is possible.
[0081]
(E) In FIG. 18, when the processing device is a hole processing constituted by the button die 21 and the pierce punch 20, a hole with higher accuracy can be obtained by pressing the periphery of the punched portion of the molded product 1 with the pad 22. Processing can be performed. If the pad 22 is configured to be pressed against the steel plate W by the elastic body 24 via the heat insulating material 25 or the like, the heat of the steel plate W is hardly transmitted to the elastic body 24.
[0082]
In addition, in the said embodiment, although what has a hat-shaped cross section is demonstrated as a press-molded article, although it is not illustrated, even if it is a thing of a U-shaped cross section, an L-shaped cross section, and a planar cross section. In addition, the portion where the rigidity reduction portion is disposed is not limited to the central portion of the press part.
[Brief description of the drawings]
[Figure 1]Reference example 1The perspective view of the press part obtained by the quenching apparatus of the press part which shows.
[Figure 2]Reference example 1Sectional drawing of the quenching apparatus of press parts of.
3 is a cross-sectional view showing a main part of the quenching apparatus in FIG. 2;
4 is a graph showing the hardness state of the main part in FIG. 3;
[Figure 5]Reference example 2The perspective view of the quenching apparatus of press parts of.
FIG. 6 is a graph showing the change in hardness of a molded product obtained by taking the thermal conductivity of the mold on the horizontal axis and the hardness (HV) on the vertical axis.
FIG. 7 shows the first of the present invention.1Sectional drawing of the quenching apparatus of the press parts of embodiment of this.
FIG. 81The process figure which divides and shows the action | operation of embodiment of (A) and (B).
FIG. 9 is a process chart showing the operation following the process of FIG. 8 separately in (A) and (B).
FIG. 10 is a graph showing a temperature change of the pressed part in FIGS.
FIG. 111The perspective view which shows an example of the hardening state of embodiment of this.
FIG. 121The graph which shows the quenching hardness by embodiment.
13 is a cross-sectional view of a press part hardening apparatus showing a modification of FIG.
FIG. 14Reference example 3Sectional drawing of the quenching apparatus of press parts of.
15 is a cross-sectional view showing the operation of the quenching apparatus shown in FIG.
16 is a cross-sectional view showing the operation following FIG.
17 is a cross-sectional view showing the operation following FIG.
FIG. 18 is a cross-sectional view showing a modified example of the pierce punch.
FIG. 19Reference example 3Sectional drawing which shows the modification of the hardening method of the press parts of.
FIG. 20 is a perspective view of a vehicle body structure showing an example of an application location of a pressed part according to the present invention.
[Explanation of symbols]
A quenching part
W steel plate
1 Press parts (molded products)
2 Stiffness reduction part
5 Mold
6 die
7 Punch
6A, 7A hollow
6C, 7C Mold materials with different heat conduction
8 Blank holder
10 Heating element as heating medium
16 Insulation
20 Piercing punch as a processing device
21 Button die as processing equipment

Claims (4)

In the quenching method of the press part to obtain a molded product in which the quenching hardness is changed for each part by changing the cooling rate for each part of the molded product shape by the mold simultaneously with the press molding of the heated steel plate,
The mold is provided with a heating medium that can be projected and retracted from the molding surface and is biased to protrude.
Prior to the formation of the heated steel sheet by the forming mold, the heating medium is brought into contact with the heated steel sheet to suppress the temperature drop of the heated steel sheet at the contact site,
As the heated steel sheet is formed by the forming surface, the heating medium is retracted to the forming surface while maintaining the contact state, and the heated steel sheet is press formed.
A method for quenching a pressed part, characterized in that the cooling rate for each part of the molded product shape is varied . The method for quenching a pressed part according to claim 1, wherein the forming die includes a heat insulating means on a forming surface that sandwiches a heated steel plate facing the heating medium . In the quenching apparatus for press parts to obtain a molded product in which the quenching hardness is changed for each part by changing the cooling rate for each part of the molded product shape by the molding die at the same time as the press molding of the heated steel plate with the molding die,
The mold temperature of each molded product shape part of the mold is arranged so as to be able to protrude and project from the molding surface and is urged to protrude and contact the heated steel plate before coming into contact with the molding surface, so that the heated steel plate is molded by the molding surface. with varied by heating of the heating medium is arranged to be accommodated in the molding surface, hardening apparatus features and to pulp-less components to varying the cooling rate of the molded article each shaping site. The press die quenching apparatus according to claim 3, wherein the forming die includes a heat insulating member on a forming surface that sandwiches a heated steel plate facing the heating medium .

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