Toyota Motor Corporation's mold design and manufacturing technology has many unique features in management and technology. A preliminary discussion on Toyota's mold production and manufacturing technology may provide some reference and inspiration for domestic automobile mold peers who are in urgent need of improving production methods, promoting scientific management and improving manufacturing technology.

 

Toyota, I believe everyone is familiar with it. Its mold design and manufacturing technology has reached the world's advanced level, and it has unique features in management and technology. The world's automobile mold manufacturing technology is developing in these directions: computer operations gradually replace on-site operations, high-precision processing replaces manual labor, mold design and manufacturing are highly standardized, and single-piece production methods develop towards assembly line production methods, etc.

 

Mold design is actually divided into three parts: stamping process design, die surface design and structural design. Combined with our domestic mold manufacturing situation, Toyota is very different from us in the following areas, which is worth learning from.

 

How is Toyota different in the stamping process design link?

 

1. Fine die surface design: Toyota completes the fine design of the die surface through computer surface modeling during the design stage. For example: design various draw ribs for different feed amounts, different draw rib sections in different parts of the same die set, anti-rebound, over-drawing treatment, minimum pressing surface design, unequal gap design between convex and concave dies, etc. The result of fine die surface design can greatly reduce the processing of the profile, reduce clamp repair, and reduce the time of trial die, and its role is not insignificant.

 

2. Application of sheet metal forming analysis technology: Toyota has established an analysis result library of various typical parts of the whole car body. For a new model part, if the formability does not change much, it is only referred to the original process without analysis, and only special new shapes are analyzed for sheet metal forming. Toyota's new car needs to be a prototype. For parts with special shapes, in addition to sheet metal forming analysis, simple molds are generally required for verification.

 

3. Die surface design experience accumulation mechanism: Toyota's design department has all computerized designs except for manual sketching. Generally, designers have a laptop in addition to a workstation. However, truly creative design still relies on the human brain, especially on human experience accumulation. Toyota places special emphasis on the experience accumulation mechanism: there can only be collective experience, not individual experience. Toyota's mold design and debugging process is truly a closed-loop manufacturing system. With the help of this self-improving experience accumulation mechanism, the design of molds is becoming more and more sophisticated and accurate.

 

4. Gap diagram design. In Toyota's mold surface design is actually completed by two parts: surface modeling and NC programming. In order to convey and describe the design ideas of the mold surface, a third type of diagram, the gap diagram, is generated in addition to the DL diagram and the mold diagram, also known as the quality assurance diagram.

 

5. The impact of large-scale production on design: Toyota's production scale is advanced in the world, and it has rich experience in how mold design can adapt to the requirements of large-scale production.

 

Improve material utilization:

For large-scale automobile production, improving the utilization rate of sheet materials is the first major issue in mold design. As long as the material utilization rate is increased by a few percentage points, the cost of the mold can be ignored. If a set of molds costs 400,000 yuan, which is only equivalent to the price of 100 tons of steel plates, with a life of 500,000 pieces, an average of 0.2kg of steel plates per piece can be saved, which is enough to save the cost of this set of molds.

 

Reduce stamping process:

The trend of mold design is the merging of parts, the mold closing of left and right symmetrical parts, and the mold closing of front and back sequential parts. The original several parts are combined into one part, and different parts are combined into one set of molds. The molds are getting bigger and bigger, the single-piece process is greatly reduced, and the number of molds for the whole vehicle is getting smaller and smaller, which plays a key role in reducing the cost of stamping. For example: Toyota has reduced the mold coefficient of the whole vehicle parts from the past 3 to about 2. Stamping automation: In order to adapt to the full automation of the stamping line, the mold must consider the loading and unloading of the robot, the automatic discharge of waste, and the widespread use of pneumatic, automatic and sensor devices.

 

Rapid mold replacement:

The mold change time of the stamping line has also become an issue that must be considered in mold design. For example: the drawing mold completely replaces the double-action with a single-action, the mold is automatically clamped, and the mold is changed without changing the ejector pin, etc.

 

Design and processing of mold structure:

Design has two purposes: one is for design itself, and the other is for manufacturing. Designers gradually improve their design ideas in the process of drawing. On the other hand, the design should be oriented to manufacturing, with the ultimate goal of improving production efficiency.

 

1. Entity design: separation of mold surface design and structural design: Toyota completely separates mold structure design from mold surface design. The former is entity design, while the latter is still surface design. In structural design, the mold surface is only schematic and can be used for real mold processing, but not for mold processing. This division of labor greatly simplifies mold entity design.

 

2. Real mold CNC processing: In Toyota, real mold production employees have completely changed from manual production to a large amount of CNC programming. Simple manual bonding and trimming work on site is performed by temporary workers. Real mold CNC production directly benefits from entity design, while improving the accuracy of castings, bringing great advantages for subsequent fine processing.

 

3. Structural surface CNC processing: The mold structural surface is the machined surface other than the mold surface, such as: guide surface, insert installation surface, screw hole, other surfaces to be processed, etc. These are also processed by programming and CNC in Toyota. Entity design makes it possible to program and process the structural surface of the mold. Toyota has truly achieved CAD/CAM integration in mold structure through physical design. Only through integration and the removal of the constraints of drawing two-dimensional drawings can physical design show its value. The two should develop synchronously and complement each other. This is the experience Toyota provides us.

 

High-precision processing:

The processing of mold surface is the focus of mold processing. Toyota has vigorously developed high-precision mold surface processing technology in recent years and achieved refreshing results.

 

1. High-precision processing of mold surface: High-precision processing of mold surface is mainly reflected in the following aspects: improving the processing accuracy of mold surface, improving the degree of processing in place, and realizing the fine design of mold surface. In addition to the management of machine tool accuracy and tooling, high-precision processing is mainly achieved by improving programming technology.

 

2. High-precision processing of two-dimensional cutting edge: Toyota's two-dimensional cutting edge insert processing is adopted on a special insert processing line. The single block processing is alive. The processing accuracy can reach the level of pin positioning assembly and mold closing without gap.

 

3. The effect of high-precision processing: Toyota has achieved the goal of less benchwork and no benchwork on the mold surface through high-precision processing. According to Toyota's standard plan, there are only seven bench working days between the completion of machining and the first mold trial, which is basically the bench assembly time, and there is no bench grinding time.

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