JP2018103261A - Hot stamping system for parts assembly manufacturing - Google Patents

Abstract

The invention provides a hot stamping system for manufacturing an automobile body part assembly with reduced exclusive area and energy consumption. Hot forming a part constituting an automobile body by a single manufacturing unit A hot stamping system for manufacturing component assemblies is provided. The system includes an equipment part (2) for producing a fixed part part and an equipment part (3) for producing a movable part part. Each equipment part (2) and (3) has a manufacturing unit (4) which receives supply of the raw material (5) cut | disconnected by the required dimension beforehand, respectively. Each manufacturing unit (4) includes a material supply rack, two handling robots, and a stamping unit including a joule heating device and a press. [Selection] Figure 1

Description

  The present invention relates to the manufacturing industry, in particular the automotive industry. The present invention relates to a hot stamping system for automotive parts that can produce a set of automotive parts known as white bodies or closures, and by forming the body of the automobile in a single production plant, the cost and Labor can be reduced.

  Hot forming technology has been successful in producing parts that are complex in shape and have high mechanical strength, especially in the automotive industry. This technique utilizes both the good formability due to reaching high heat distortion temperatures and the austenite phase transition that occurs during component cooling. This technology uses a thin steel plate that can be trained, and thus contributes to reducing the weight of the vehicle and further improving the fuel consumption of the automobile.

  An important problem to be solved is the fact that the stamping workability of steel is impaired by the improvement of the mechanical strength of the steel. However, the development of metallurgy over the past 40 years has led to the creation of advanced high strength steel (AHSS steel). AHSS steel is being sought to achieve both high mechanical strength and formability of steel sheets. Nonetheless, the continual search for performance improvement shows that the progress achieved so far is dramatic but not sufficient. While the stamping formability of AHSS steel is certainly greatly improved, it is still insufficient in many practical situations. The main problem is not the conformability of the steel itself, but the so-called springback that occurs after the stamping process. The springback phenomenon is very remarkable in the AHSS steel sheet. Although the steel sheet is actually formed, the steel sheet is subjected to distortion due to residual stress immediately after leaving the forming matrix. This distortion more or less affects the dimensional accuracy of the part.

  A solution to this problem is to separate the processing characteristics and application characteristics of the material. That is, there is no reason not to heat the steel plate before stamping. This method can be scientifically explained as a method utilizing the phenomenon that the crystal plane of slip dislocation is activated and the crystal plane is easily moved at a higher temperature.

  The hot forming process is relatively simple. First, the material is cut from a coil of boron and microalloyed low carbon steel. Next, the material is introduced into a continuous heating furnace (having an average length of 40-60 m) and austenitized at 850-950 ° C. The steel surface is protected from the rapid oxidation that occurs at the high temperatures of the process. In this case, the most common alternative is to coat the steel surface with an AlSi layer, but instead of coating, a method of creating a protective atmosphere inside the furnace can also be used.

  After a preheating time of 4-10 minutes, the blank is sent to a stamping press. In the stamping press machine, the material is formed and the steel sheet is immediately trained in a water-cooled matrix. After a cooling time of 15-25 seconds, the forging is complete, the burrs that have formed on the part are removed and removed from the matrix at a temperature of about 150 ° C. Thereafter, the parts are cooled by contact with air, and a training effect is obtained.

  Hot stamping is not exactly a new process and was first developed in Sweden in 1973. That was exactly the year that the first serious challenge in the automotive industry was caused by soaring oil prices. However, the application of hot stamping to actual production remained limited until it increased exponentially in the early 2000s. Currently, hot stamping molding is mainly used in the production of passenger car intrusion prevention components and structural reinforcement members. These parts are relatively large in size, complex in shape, and high in mechanical strength, making it difficult to use cold stamped AHSS steel.

  It is estimated that 60,000 to 80,000 tons of steel sheets were consumed for hot stamping in Europe alone during 2004. In 2008, just before the financial crisis that started with the Lehman shock, the amount of steel consumed for hot stamping in the following year will rise to 300,000 tons in Europe alone, and 20 new hot stamping in Europe. The line was expected to be operational.

  Hot stamping was also successful in the United States. As many as 33 bumpers were manufactured in the United States by hot stamping molding for various car models from several automakers such as Volkswagen, General Motors, Citroen, Ford and Smart. As the raw material steel, steel materials of SAE10B21 and SAE15B21 and a thickness of 1.50 to 3.50 mm were mainly used. The average values of typical post-curing properties were a yield limit of 1,140 MPa, a breaking strength of 1,520 MPa, an elongation of 12%, and an HV hardness of 479. Currently, 22Bn B5 steel is widely used.

  In hot stamping, the most important step in determining the mechanical properties of the finished part is quenching, usually done in a water-cooled matrix. Therefore, the chemical composition of the steel used is determined by the required mechanical properties of the final part, the thickness of the workpiece, and the cooling rate in the matrix during quenching necessary to ensure an appropriate degree of training, Determined by.

  A composition having a carbon content of about 0.20% and a relatively high manganese content is suitable for hot stamping steel. Although cold forming of AHSS steel has not reached its limit, it can be said that hot stamping is currently the only method for producing parts that are complex in shape and require high mechanical strength. By utilizing the austenitization of the steel material, the mechanical resistance at the time of processing is low and the ductility is high, so the forming process becomes easy. In addition, the phenomenon resulting from further metallurgical modification can be used to reduce the weight of the part and improve performance.

  However, the use of large heating furnaces (having an average length of 30-60 m) and the high temperature reached complicate the process and equipment. It involves significant investment, high energy consumption to heat the parts, and reduced productivity due to the long time required for the heat treatment stage.

  In order to improve the production of stamping parts used in the automotive industry, the present invention allows a series of parts ("white body", "car body", "closure") that make up the car body to be produced in a single factory. Features a hot stamping system that allows stamping. The hot stamping system is a manufacturing system that uses a hot forming process and a specific Joule heating system (according to the invention patented by the inventor of the present application) to reduce the weight of the vehicle body, optimize energy efficiency, and The purpose is to improve vehicle safety by using high strength steel.

This system replaces the heating furnace in the conventional system with heating equipment. Thereby, compared with the conventional system, the installation area of the whole system can be greatly reduced from 1800 m ² to 300 m ² . As a result, the costly heating furnace need not be maintained. In addition, intermittent stamping can be performed without performing the dipping process. The dipping process is a high cost factor, especially in continuous production. This is because a high temperature is required for the immersion, so that energy consumption due to heating of the atmosphere in the furnace increases and the deterioration of the heating furnace becomes severe.

  The system further enables the use of a steel material having a metal coating (Zn, ZnFe, ZnNi, etc.) by hot dip galvanization or electrolytic galvanization in the process described above. Conventional processes use steel with an AlSi metal layer coating. Furthermore, according to the conventional process, a surface layer is formed on the component, thereby generating a microcrack. The process used in the present system minimizes the occurrence of these microcracks.

  The hot stamping system for manufacturing the set of parts that is the subject of this patent will be better understood with reference to the accompanying drawings. These drawings are included herein and include reference numerals along with a description of the technical details. These drawings are not intended to limit the present invention with respect to the dimensions, characteristics, and finish specifications listed therein, nor are they intended to limit the scope of actual applications.

The flowchart of the manufacturing process which showed the manufacturing operation for every step. Manufacturing unit showing equipment related to stamping.

  The figures and reference numbers explain the invention. It is an object of the present invention to stamp a set of fixed and movable parts ("white body", "body car", "closure") constituting a vehicle body by a single manufacturing unit (1). It relates to a hot forming system. The system includes an equipment part (2) and an equipment part (3). The equipment part (2) is for producing parts of the fixed part, and the equipment part (3) is for producing parts of the movable part. The equipment parts (2) and (3) each have as many production units (4) as are necessary for the production of the assembly. The material (5) is cut into necessary dimensions in advance, and after being inspected (6), it is supplied to the manufacturing unit (4). The material (5) is made suitable for insertion into a stamping tool (matrix) in accordance with the shape and dimensions of the parts to be produced in each manufacturing unit (4), and then the equipment parts ( 2) and the equipment part (3) for producing the parts of the movable part.

  In equipment parts (2) and (3), there is one production unit (4) for each specification of the parts to be produced. The production unit (4) includes a material supply rack (8), two handling robots (9) and (11), and a stamping unit including a Joule heating device (10) and a press machine (12). . The press machine (12) has a tool (matrix) corresponding to the part to be stamped. The first robot (9) draws the material from the material supply rack (8) and places the material in the heating device (10). After the steel plate is heated, the first robot (9) takes out the heated part, supplies the tool to the press machine (12), and is processed into a predetermined form and shape. Thereafter, the second robot (11) takes out the molded part from the press machine (12) and stores the part in the storage rack (13).

  Both hot and cold parts are moved by a dedicated robot arm and a dedicated transport system specially designed for this application. In the case of moving hot parts, these transporters are selected from materials that adapt to the temperature and radiation of the steel and are not damaged.

  In the heating device (10), the heating is performed by energization heating (heating by the Joule effect), and the rate of temperature rise reaches 400 ° C./second. By arranging the heating device (10) close to the press machine (12), the exclusive area can be limited to an area slightly larger than the size of the component to be heated. Thereby, the installation space of each manufacturing unit (4) can be utilized more effectively.

  The present invention can be used, for example, for manufacturing automobile parts.

DESCRIPTION OF SYMBOLS 1 Manufacturing unit 2 Equipment part 3 Equipment part 4 Manufacturing unit 5 Material 6 Inspection 7 Distribution 8 Material supply rack 9 1st robot 10 Joule heating device 11 2nd robot 12 Press machine 13 Storage rack

Claims (7)

A set of fixed and movable parts ("white body", "body car", "closure") that make up the body of an automobile can be hot-formed by a single manufacturing unit (1);
An equipment part (2) for producing parts of the fixed part and an equipment part (3) for producing parts of the movable part;
Each of the equipment parts (2) and (3) has a production unit (4) that receives supply of a material (5) that has been cut in advance to a necessary size, and has a quantity necessary for production of the assembly;
The material (5), after undergoing inspection (6), is made suitable for insertion into a stamping tool (matrix) according to the shape and dimensions of the parts to be produced in each production unit (4), Distributed (7) to the equipment part (2) and the equipment part (3);
A hot stamping system for manufacturing a part assembly.   Said equipment parts (2) and (3) have a production unit (4) which is defined according to the specification and shape of the parts to be produced and which corresponds to the individual stamping for each part type on a one-to-one basis. The hot stamping system for manufacturing a part assembly according to claim 1. Each of the production units (4)
Material supply rack (8),
First robot (9),
A second robot (11), and
A stamping unit having a joule heating device (10), and a press machine (12) having a tool (matrix) corresponding to the part to be stamped,
The hot stamping system for manufacturing a component assembly according to claim 1, comprising: Each of the production units (4)
The first robot (9)
Pull out the material (5) from the material supply rack (8),
Placing the material (5) in a Joule heating device (10);
After the steel plate is heated, take out the heated parts,
Supplying tools to the press for forming and cooling;
The second robot (11)
After the parts are molded, the molded parts are removed from the press machine (12),
Storing the parts in the storage rack (13);
The hot stamping system for manufacturing a part assembly according to claim 1 or 3. The movement of hot and cold parts is both carried out by a dedicated robot arm and a dedicated transport system specially designed for this application;
In the case of moving hot parts, the robot arm and the transfer system will be selected for materials that will adapt to the temperature and radiation of the steel and will not be damaged;
The hot stamping system for manufacturing a part assembly according to claim 1 or 4. Joule heating device (10) is placed next to the press (12),
The exclusive area of the press machine (12) is slightly larger than the workpiece to be heated,
The hot stamping system for manufacturing a part assembly according to claim 1. The Joule heating device (10) heats the steel sheet by the Joule effect,
The heating rate due to the Joule effect is 400 ° C./second or more,
The hot stamping system for manufacturing a part assembly according to claim 1 or 6.

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