CN101486062A - Thermoforming and edge-cutting integrated technique and mold of high-duty steel part - Google Patents

Abstract

The invention provides a hot forming and trimming integrated process and mold for high-strength steel parts. The integrated process is to set the trimming tool on the hot forming die of high-strength steel parts. Before the high-strength steel sheet is hot-stamped, the high-strength steel sheet heated to complete austenitization is placed in the hot-forming die for stamping After the thermoforming mold is closed, the trimming tool on the thermoforming mold is then used to trim the stamped workpiece. The integrated mold includes an upper die, a lower die, an upper trimming tool and a lower trimming tool. The upper end of the upper die is equipped with an upper die oil cylinder, the piston rod of the upper die oil cylinder is connected with the upper trimming tool, and the lower die is installed with a lower die An oil cylinder, the piston rod of the lower mold oil cylinder is connected with the lower end of a push rod, and the upper end of the push rod is connected with the lower trimming tool. The invention reduces the equipment investment and production cost of thermoforming, shortens the production cycle, has high trimming quality, and high dimensional accuracy and shape accuracy of parts.

Description

Integrated Hot Forming and Edge Trimming Process and Die for High Strength Steel Parts

technical field

The invention relates to a hot stamping forming and edge trimming process and a die of high-strength steel, advanced high-strength steel and ultra-high-strength steel stamping parts, and belongs to the technical field of forming high-strength steel plate metal parts.

Background technique

At present, in the field of automobile manufacturing, people's demand for high safety, low dead weight and good fuel economy has become an important driving factor for technological progress. Manufacturers are making consumers' wishes come true by introducing new safety concepts and lightweight body structures. Especially in terms of body structure, through the use of high-strength steel, advanced high-strength steel and ultra-high-strength steel, the crash performance of the car is improved and the requirement of lightweight is also achieved. However, with the increase of steel strength, the elongation rate decreases, and the formability of the material is also greatly reduced. During the forming process, problems such as cracking, wrinkling, difficult to control the size and poor shape are prone to occur. The traditional cold stamping forming process can no longer meet the technical requirements. and production development needs.

In recent years, scholars at home and abroad have developed a new hot stamping process for high-strength and ultra-high-strength steel sheets, which heats high-strength steel and ultra-high-strength steel sheets to the austenitizing temperature ( 900～950℃), and keep it in the austenite zone for 5 minutes, then transfer the sheet to the press, and perform stamping forming and quenching in the stamping die at the same time, so that the formed parts can obtain 100% martensite structure. The process can reduce the weight of automotive structural parts while improving crash performance and fatigue strength.

Chinese patent document CN101288889 discloses a "ultra-high-strength steel plate hot stamping die", which includes an upper mold base and a punch fixed on the upper mold base, a lower mold base and a concave mold fixed on the lower mold base, and A cooling water channel is arranged in the mold, and the cooling water channel is connected with a cooling water circulation system.

Chinese patent document CN1829813 discloses a kind of "hot forming method and hot forming member". After heating a steel plate with a specific composition above the austenite point temperature (Ac3) and maintaining it, the final product shape is formed. During forming or from When cooling the forming temperature after forming, the cooling rate to the Martens point temperature (Ms point) of the formed component is above the critical cooling rate, and the average cooling rate from the Ms point to 200 °C is 25~150 °C/ s cooling and quenching treatment.

In the case of high dimensional accuracy requirements, through-holes on thermoformed parts or press flanges on thermoformed parts, secondary processing of thermoformed parts is necessary. In the cold stamping process, the stamping die is generally used for secondary processing such as punching and trimming, but it is extremely difficult to use a conventional die structure for secondary processing in the hot stamping process; Trimming or punching of components requires a large processing load, and the metal die will be damaged or its life shortened. For hot-formed parts of ultra-high-strength steel plates, it is even impossible to process with cold stamping dies.

In order to make hot-formed high-strength parts meet the corresponding dimensional accuracy and shape requirements, five-axis laser cutting technology is currently used for trimming. However, the efficiency of laser trimming is low. A hot stamping production line often requires several sets of laser trimming lines. In addition, each set of laser trimming lines requires corresponding fixtures to position and clamp the parts, so the equipment occupies a large area, requires a lot of equipment investment, and high production costs. In addition, after laser edge trimming, the edge trimming of thermoformed parts will contain some metal particles formed after the solidification of molten metal, which requires subsequent grinding processes to remove metal waste, resulting in long production cycles for thermoformed parts and limiting thermal Promotion and application of stamping technology. When using laser edge trimming, the completion time is limited by the size of the part and the number of holes. The simplest part takes more than 30 seconds from the part being fixed to the edge trimming fixture to the completion of cutting. For complex parts, it may take several minutes.

Chinese patent document CN2617549 discloses a "new hot punching and trimming die", which is used for hot punching and trimming dies for forgings. The die disclosed in this patent can only use the slide block movement of the press to complete a single Punching, trimming, but not for forming, trimming or punching compound, in addition, the mold structure is used for steel block forging, belongs to the field of volume forming, and cannot be used for high-strength sheet metal belonging to the field of sheet metal forming Punch or trim.

Contents of the invention

The invention aims at the problems existing in the secondary processing technology used in hot forming and edge trimming of high-strength or ultra-high-strength steel stamping parts, and provides a hot-forming and high-quality high-strength steel parts with simple structure, high production efficiency and good quality. The trimming integrated process provides an integrated mold for realizing the process at the same time.

The hot forming and trimming integrated process of the high-strength steel parts of the present invention are:

Firstly, a trimming tool is set on the thermoforming die of high-strength steel parts, and before the high-strength steel sheet is hot-stamped, the high-strength steel sheet heated to complete austenitization is placed in the thermoforming die for stamping, hot forming After the mold is closed, the edge trimming tool on the thermoforming mold is used to trim the stamped workpiece. After the completion, the thermoforming mold is cooled, and the mold parts that are in contact with the formed part are used to quench the formed part.

The hot forming and trimming integrated mold of high-strength steel parts that realizes the above-mentioned integrated process adopts the following technical scheme:

The hot forming and trimming integrated mold for high-strength steel parts includes an upper mold, a lower mold, an upper trimming tool and a lower trimming tool, and a cooling water channel is provided in the upper mold and the lower mold, and the bottom of the upper mold is outside The contour is consistent with the internal contour of the part, the cavity contour of the lower die is consistent with the external shape of the part, the upper end of the upper die is equipped with an upper die cylinder, the piston rod of the upper die cylinder is connected with the upper trimming tool, and the bottom of the lower die A lower mold oil cylinder is installed, the piston rod of the lower mold oil cylinder is connected with the lower end of a push rod, and the upper end of the push rod is connected with the lower trimming tool.

The upper trimming tool and the lower trimming tool are segmented according to the outer shape of the part, and the upper trimming tool and the lower trimming tool have the same number of segments.

The thickness of the upper trimming tool and the lower trimming tool is 1.5~4.0 times of the wall thickness of the processed part.

In the present invention, after hot stamping and before in-mold quenching of the formed part, the trimming tool inside the mold that does not rely on the energy of the press is used to trim the edge of the hot-formed part, and then in-mold the part after trimming. Quenching, this process reduces the equipment investment for hot forming, reduces the floor area of the equipment, reduces the production cost of hot forming parts, shortens the production cycle of hot forming parts, and the trimming quality of hot forming parts is high, and the High dimensional accuracy and shape accuracy. Using the edge trimming process of the present invention, the completion time is 1-2 seconds, and it is not limited by the size and shape of the parts.

Description of drawings

Fig. 1 is a structural schematic diagram of an integrated die for thermoforming and edge trimming of the present invention (closed state before edge trimming).

Fig. 2 is a schematic diagram of the state of the thermoforming edge trimming die shown in Fig. 1 after edge trimming is completed.

Fig. 3 is a top view of the lower die in the thermoforming trimming die shown in Fig. 1 .

Fig. 4 is a left side view of Fig. 1 .

Fig. 5 is a left side view of Fig. 2 .

Among them, 1. Upper die, 2. Lower die, 3. Upper trimming tool, 4. Lower trimming tool, 5. Thermoformed parts to be trimmed, 6. Upper die cylinder, 7. Piston rod, 8. Oil hole , 9, the lower oil hole, 10, the ejector rod, 11, the piston rod, 12, the lower die cylinder, 13, the upper oil hole, 14, the lower oil hole, 15, trimming waste.

Detailed ways

The thermal forming trimming integrated process of high-strength steel parts of the present invention, firstly, corresponding trimming tools are arranged on the upper mold and the lower mold of the thermoforming mold of high-strength steel parts, and oil cylinders or air cylinders are installed on the molds. , the piston rod of the oil cylinder or cylinder is rigidly connected with the trimming tool. The process of this process is that the sheet heated to the austenitic state is placed on the lower mold of the thermoforming mold → driven by the press, the upper and lower molds are closed to complete the thermoforming of the part → the oil cylinder or air cylinder in the mold drives the trimming tool to move , complete the edge trimming→introduce cooling medium into the cooling water channel inside the mold to cool the mold to realize the quenching of high-strength parts. The formed waste → Driven by the press, the upper and lower molds are opened, and the waste formed by the thermoformed parts and trimming is taken out.

Figure 1, Figure 3 and Figure 4 show the structure of an integrated mold for thermoforming and edge trimming of a part, and Figure 2 and Figure 5 show the state of the mold after edge trimming. The mold includes an upper mold 1 and a lower mold 2, adopts the technology disclosed in CN101288889, and is provided with a cooling water channel in the upper mold 1 and the lower mold 2. The outer contour of the bottom end of the upper mold 1 is consistent with the shape of the part, and the outer contour of the cavity of the lower mold 2 is consistent with the outer contour of the bottom end of the upper mold 1 . The upper end of the upper mold 1 is equipped with an upper mold oil cylinder 6, and the piston rod 7 of the upper mold oil cylinder 6 is threadedly connected with an upper trimming tool 3; the bottom of the lower mold 2 is equipped with a lower mold oil cylinder 12, and the piston rod 11 of the lower mold oil cylinder 12 The lower end of the push rod 10 is connected together by threads, and the upper end of the push rod 10 is connected together with the edge trimming tool 4 by threads. The upper mold 1 is also fixed on the upper template, the upper template is fixed on the slider of the press through bolts and pressure plates, the lower mold 2 is fixed on the lower template through screws and pins, and the lower template is fixed on the workbench of the press through bolts and pressure plates superior. During the hot forming process, the upper die 1 moves downwards driven by the press slider, and finally the high-strength steel plate placed on the upper surface of the lower die 2 and heated to austenitic state is pressed into the lower die 2, so that the high-strength The plate is formed in the mold to form an untrimmed thermoformed part 5 to be trimmed.

After the parts are formed, the auxiliary supporting hydraulic system controls the piston rod 7 of the upper die cylinder 6 to drive the upper trimming tool 3 to move downward, while the hydraulic system controls the piston rod 11 of the lower die cylinder 12 to drive the ejector rod 10 and the lower trimming tool 4 to move downward. down exercise. Under the combined action of the upper surface of the lower die 2, the upper edge trimming tool 3, and the lower edge trimming tool 4, the edge trimming waste 15 is separated from the thermally formed part 5 to be trimmed, thereby completing the edge trimming process inside the mold to form a formed part.

After edge trimming is completed, a cooling medium is introduced into the cooling channels of the upper mold 1 and the lower mold 2 to cool the molds, thereby quenching the formed parts. While feeding cooling water into the mold, the auxiliary hydraulic system controls the piston rod 11 of the lower mold cylinder 12 to drive the ejector rod 10 and the lower trimming tool 4 to move upwards, and the hydraulic system controls the piston rod 7 of the upper mold cylinder 6 to drive The upper trimming tool 3 moves upwards, and the trimming waste 15 formed by trimming is ejected from the lower die. After the formed parts are cooled, the upper mold 1 moves upwards under the drive of the press slider, the mold is opened, and the trimming waste 15 and the formed parts are taken out of the mold, and then enters the next working cycle.

The trimming process needs to cut off all the waste around the high-strength steel hot-formed part 5 to be trimmed. In order to ensure the smooth implementation of the trimming process and simplify the design of the trimming tool, the trimming tool is used as shown in Figure 5. chunked form. The peripheral contour of the high-strength steel part may be an arbitrary curve. The number of blocks of the lower trimming tool 4 is determined according to the complex program of the high-strength steel part. The number of blocks of the upper trimming tool 3 and the lower trimming tool 4 is the same. Several of all the blocks of the trimming tool will exceed the boundary line of the high-strength steel part (the dotted line in Figure 3), to ensure that the scrap can be divided into several pieces after trimming, so as to facilitate the removal of the scrap. The thickness of the trimming tool is generally determined according to the wall thickness of the formed high-strength parts. The thickness of the trimming tool is 1.5 to 4.0 times the wall thickness of the part. For high-strength parts formed from thin plates, the upper limit is taken. Strength parts, take the lower limit. During the trimming process, the upper trimming tool 3 is guided through the corresponding mounting hole in the upper die 1 , and the lower trimming tool 4 is guided through the corresponding mounting hole in the lower die 2 .

The single-piece edge trimming tool is generally long. If an oil cylinder is used to apply the edge trimming force to the edge trimming tool, it will result in insufficient edge trimming force or the edge trimming tool will be deflected due to uneven force during the edge trimming process, and the cutting speed will be accelerated. The wear rate of edge tools and dies. In order to solve this problem, as shown in Figure 4 and Figure 5, according to the size of the upper trimming tool 3 or the lower trimming tool 4, more than two upper die oil cylinders 6 or upper die oil cylinders 12 are used to provide trimming tools for the trimming tool. Force, and the oil cylinder should be evenly distributed along the trimming tool to ensure that it can provide enough trimming force for the trimming tool, and ensure that the trimming tool is evenly stressed to avoid deflection. The upper oil holes 8 of the upper die oil cylinders 6 that provide power for the upper trimming tool 3 are connected together, and the lower oil holes 9 are connected together to ensure that multiple oil cylinders of the upper die can move at the same time; provide power for the lower trimming tool 4 The upper oil holes 13 of a plurality of lower die oil cylinders 12 are connected together, and the lower oil holes 14 are connected together, so as to ensure that a plurality of lower die oil cylinders 12 can act simultaneously.

When hot-trimming high-strength steel parts, due to the high temperature of the formed parts (about 850°C), the trimming tool and the combined mold surface are easily damaged. In order to facilitate the repair and maintenance of the mold, The insert structure is adopted at the position where the trimming tool is installed. After the trimming tool or the insert is damaged, only the damaged parts need to be replaced, and there is no need to repair the entire surface of the upper mold or the lower mold.

Claims (4)

1. the hot forming of a high-duty steel part and edge-cutting integrated technique is characterized in that:

The side cut instrument at first is set on the hot-forming die of high-duty steel part, before the high strength steel plate is hot press-formed, the high strength steel plate that is heated to after the complete austenitizing is positioned over punching press in the hot-forming die, after the hot-forming die closure, then utilize workpiece after the pressing operation of cutting edge that liquidates of side cut instrument on the hot-forming die, after finishing hot-forming die is cooled off, utilize with the contacted mold component of formation of parts formation of parts is quenched.

2. the hot forming of a high-duty steel part and edge-cutting integrated mould, comprise patrix, counterdie, last side cut instrument and following side cut instrument, in upper die and lower die, be provided with cooling-water duct, the bottom exterior contour of patrix is consistent with the in-profile of part, the die cavity profile of counterdie is consistent with the outer shape profile of hot forming part, it is characterized in that: the upper end of patrix is equipped with upper mould oil cylinder, the piston rod of upper mould oil cylinder is connected with last side cut instrument, the bottom of counterdie is equipped with lower mold oil cylinder, the piston rod of lower mold oil cylinder is connected with the lower end of a push rod, and the upper end of push rod is connected with following side cut instrument.

3. the hot forming of high-duty steel part according to claim 2 and edge-cutting integrated mould is characterized in that: describedly go up the side cut instrument and following side cut instrument carries out piecemeal according to the outer shape of part, the piecemeal quantity of last side cut instrument and following side cut instrument is identical.

4. the hot forming of high-duty steel part according to claim 2 and edge-cutting integrated mould is characterized in that: the described thickness of going up side cut instrument and following side cut instrument is 1.5 ~ 4.0 times of institute's processing parts wall thickness.

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