How to plan auto stamping automatic production line
One, the significance of realizing stamping automation
Although the initial investment of the traditional artificial production line is small, but with the expansion of market demand, its inherent low efficiency, poor product quality stability and other shortcomings increasingly affect the development of enterprises. Automated production lines can solve these problems. Under the condition of mass production, higher production efficiency, stable product quality and lower production cost per piece are the advantages of automatic medium voltage production line, especially for the large-scale production of body covering parts, these advantages are more prominent. As a result, today's OEMS will directly consider automation in the early planning of large stamping production lines.
Two, the composition of automatic stamping line
In terms of equipment composition, automatic stamping production usually consists of a press and an automatic system. Here, we focus on the automatic part. The stamping automation system usually includes the stacking system, the automatic transmission system and the end of the line discharging system.
1. Unstacking system
A complete stamping automatic stacking system is mainly composed of 2 rail mobile loading carts (each loading cart is equipped with 4-8 movable adjustable magnetic force dispensers, usually permanent magnets, Used for paper separation, unloading hand (manipulator or robot), conveying device (mainly magnetic belt conveyor), paper cleaning machine (optional), paper oiling machine (optional), paper and control system, etc. This is shown in Figure 2.
After the loading cart has loaded the heap (possibly including the tray) from the heap replacement position back to the heap removal position, the sheet is picked up from the heap by the heap removal hand and transferred via the transfer device to the centering table through the cleaner and oiler. After the sheet is centered, the post-sequence stamping production can begin.
⒉ Automatic transmission system
Automatic transmission system for each process blank or workpiece transport transmission. There are two main transmission mechanisms: manipulator and robot.
With the continuous progress of stamping automation technology, the form of automatic transmission mechanism of manipulator also changes with each passing day. Different forms of automatic transmission mechanism is also the main difference between different forms of automatic punching line. The parallel four-sided manipulator structure, which was widely used at the end of last century, has been gradually phased out and replaced by high-speed and stable single-arm or double-arm cross-bar transmission mechanism. The transmission mechanisms in the Robobeam system of Gudel in Switzerland, the Speedbar system of the former MW in Germany and the H*TL system of Komatsu in Japan are all typical representatives of the transmission mechanisms of the high-speed stamping automatic line today, as shown in Figure 3.
At the same time, the transportation mode of the robot has unique characteristics, and there is a certain application space in the production line with low speed and less investment of the old line. 3. End discharging system
The discharging system at the end of the line is composed of discharging conveyor belt, lighting, workpiece inspection table, manual or automatic packing mechanism and control system. The main task is to transport the finished stamping parts to a suitable location for packing (or automatic packing), and provide conditions for stamping parts detection.
Three, the main form of stamping automatic line
At present, the form of automatic stamping line mainly has the following :1. "ordinary press + robot transmission" form
The transmission form of robot is flexible, easy to use, low cost, but poor stability, relatively slow speed, not suitable for large-scale high-speed production. 2. "Ordinary press + single arm manipulator" transmission form
Due to the relatively low cost and flexibility of single-arm manipulator transmission, there is still some room for development. 3. Transmission form of "high-speed press + horizontal bar" (high-speed line)
The cross-bar transmission has the characteristics of high speed and high stability, and has been widely used in the production of large covering parts. 4. "Multi-station press + step type" transmission form
The production line has many years of history, the transmission mode from the beginning of Z mechanical transmission to today's electric control transmission, the overall structure from a single slider development to single slider and multiple slider coexistence. Because of its fast speed and high stability, it has been widely used by each main engine factory. Especially multi - slider multi - station, its basic characteristics and high - speed line close.
Four, stamping production line planning and selection principles
The production line you choose depends on which stampings you need to produce. The large stamping parts, which account for 10% of the body, generally adopt punching lines with a gross tonnage of more than 6000 tons. About 25% of the medium and large stamping parts are made with a stamping line of about 4000 tons. About 25% of the medium stamping parts use about 2500 tons of stamping production line. The remaining 40% of small and medium parts are basically made of production lines below 1000 tons.
As for the form of the punch line, it depends on the type and output of the stamping parts needed to be produced. Small batch of small varieties, usually using ordinary artificial lines, a large number of varieties, suitable for high-speed stamping automatic lines. FIG. 4 shows the reference principle for selection of punching line.
Production capacity accounting of automatic stamping line
Capacity accounting is one of the key links in automatic stamping production line planning. The result of capacity accounting directly determines the amount of production line input, and also directly affects the investment.
Based on the results of line selection, combined with the production organization level, prior and peer experience, the common production cycle (SPM), comprehensive failure rate (equipment and equipment failure caused by downtime ratio and production organization problems) and single change time can be obtained. In addition, according to the actual situation of factory production management, we can know the standard batch (number of production pieces per batch), daily working time, daily meal stop time and annual working days.
As long as you know the annual output, combined with a given production schedule and type of stamping, you can easily calculate the number of production lines required.
Six, stamping automatic line planning to consider the main factors
Stamping automatic line planning is a relatively complex process. In addition to the capabilities accounting mentioned above, there are a number of factors to consider.
1. Determine whether to use the synchronization technology
The application of synchronization technology in the field of stamping automation has been widely recognized. It is of great significance to improve the production rhythm.
Traditional stamping automation production process, the press always adopt the "single" operation mode, blanking hand (the manipulator/robot) need to wait for stamping press to complete the whole cycle slider to action after back to the top dead center has stopped, feeding hand (feeding manipulator/robot) need to hand out under, such as the compressor to start after the work area, And the press slider needs to wait for the blanking hand to completely exit the press work area before starting to go down, each cycle is long, which directly affects the production rhythm of the whole line.
Synchronous technology refers to the "continuous" operation of printing presses in the production process. By calculation, the stevedore and the press slider start "synchronously". After the slider rises to a certain Angle (before returning to TDC), the unloading hand begins to pick up the material. Before the slider drops to a certain Angle, the loading hand completes the feeding, and the picking and feeding actions are completed without interference in the whole process. At the same time, in order to ensure that the blanking hand has enough time to send the workpiece to the next process after the completion of taking parts, the adjacent two press slider movement process always maintains a reasonable phase difference, so that the blanking hand can work relatively longer period.
Especially for large sheet metal stamping production, high-speed stamping automatic line and synchronous technology has more obvious advantages than the single slider multi-station method.
⒉ press key parameters - slide travel
When planning the production line, there are many press parameters to be considered, among which the slider stroke directly affects the feasibility and difficulty of automation, which should be paid attention to in the planning.
Slider stroke selection, and need to produce the drawing depth of stamping parts, the height of the end pick up directly related to. Planning to determine the slider travel, must ensure that the loading and unloading hand grasp the workpiece horizontal movement process of the end of the pick up and upper die and the highest point of the upper die to maintain enough safe space.
Because the drawing depth of large covering parts is more than 200mm, so the stroke of the press slider of large high-speed stamping automatic line is generally above 1000mm.
3. Structure and shape of mold and end picker
In order to obtain a more reasonable interference profile, the structural shape of the die and end picker should be considered in addition to the inherent parameters or characteristics of the press, such as slider stroke and speed-acceleration curves. Reasonable structure of die and end picker can effectively make up for the shortcomings of automation, so as to improve the feasibility of automatic production of stamping.
In addition, in the design of the mold should also consider the following content: the same production line clamping height difference should not be too big; The lower die is equipped with sensors whenever possible to fabricate parts in place. The position of the mold installation slot is as unified as possible (can reduce the number of automatic fixtures, reduce the cost); The waste material can be smoothly discharged from the table (some difficult to discharge position added stamping device); The molding die is equipped with part jacking device (such as ejector pin or ejector cylinder), avoid the use of large wedge mechanism, and use rotating wedge mechanism whenever possible.
4. Requirements for steel sheet stacking
Compared with manual line, automatic stamping production has more strict requirements on the regularity degree of steel sheet blank stacking. If the stacking is not tidy enough, it will cause the magnetic separation effect is not good (easy to appear double phenomenon), and the position of the unstacking hand of the grasping board is not accurate enough. Therefore, before the automatic line input, in order to ensure the production efficiency to reach the target value, must be clear about the requirements of steel sheet stacking.
6. Requirements for production management
(1) Timely offline maintenance of molds to reduce online maintenance time;
(2) There is little difference in mold closing height between adjacent production batches (can reduce the adjustment time of mold height); (3) The blank and mold are ready before the production batch switch;
(4) Timely transfer of finished products;
(5) Maintain good environmental cleanliness; (6) Standardization of equipment operation and maintenance.
