With the growing maturity of microelectronics and computer technology, the development of CNC technology in China has been promoted. The successful development of domestic CNC systems has ensured the quality and performance of CNC machine tools in China. CNC machine tools have been widely used in various fields due to their strong adaptability to workpiece modification, high machining accuracy, and improved productivity.
CNC technology has been widely used in sheet metal machine tools. It solves the problems of high precision, complex shape and large batch of parts in sheet metal processing. CNC sheet metal machine tools include CNC shearing machine, CNC laser cutting machine, CNC punch, CNC bending machine, welding machine, flame cutting machine, etc. Their application in production greatly improves the processing capacity of sheet metal, ensures the quality and output of sheet metal parts, and greatly reduces the labor intensity of workers.
Cutting is the first process in the process of sheet metal processing. The accuracy of cutting directly affects the processing quality of the following processes. The application of numerical control plate shears ensures the size of cutting and the work error of cutting diagonal. Numerical control plate shearing machine is composed of numerical control device, servo system, measuring device and machine tool. The servo system is composed of three servo motors and servo drive devices. There are two servo motors positioned in front of the machine tool. Generally, one main motor works independently, with a processing range of 2-500mm. If the bevel is processed, the auxiliary motor works. The CNC system gives two different instructions to form the bevel. There is a servo motor in the rear positioning, which is mainly used to process large plate products, with the processing range of 150~4000mm. For example, the QC12K series numerical control plate shears made in Shanghai are equipped with the Swiss CYBELEC DNC60 series, which can store 36 sequences, and the internal memory capacity is 100 sequences.
S stamping is an important link in sheet metal processing, and the CNC punch can replace the processing capacity of the past three punches. The productivity has been greatly improved. CNC punch press is a machine tool with a wide range of uses, including single punch and turret. This paper takes CNC1000 as an example, which is produced in Italy. Machine tool of C-type structure, processing range: 1270 × 1000mm, the turret has 19 mold stations, which are divided into upper and lower parts to install the punch and die respectively. The external dimensions of the die are 25.4mm, 47.62mm, 88.9mm, 125.43mm, 158.4mm and 210.00mm in diameter. The CNC punch generally has X, Y and Z axes. The X axis is the 0 degree direction of the machine tool, the Y axis is the 90 degree direction of the machine tool, and the Z axis is installed on the turret to control the mold angle.
The machine tool operator shall determine the processing plan according to the part drawing and process requirements, and prepare the program sheet. The operator directly writes the program into the program memory in EDIT mode through the operation panel of the machine tool; With the development of CAD/CAM and CIMS technology, the operator can input graphics into the computer to generate programs through computer related software, copy them into disks, and input them into the CNC system through disk drives. It can also be input by computer and numerical control system serially. The programming instructions of the CNC punch are divided into G code and M code. G code is used to instruct the machine tool to carry out processing movement and interpolation mode. For example, G91 incremental command, G90 absolute command, G29 arc punching, G68 step punching circular arc. M code is the code that instructs the machine tool to do some auxiliary actions. If M30 program stops. After the inspection procedure is correct, release the caliper and put in the workpiece to close the caliper. Start the oil pump and punch to complete the processing.
CNC punch has the following characteristics:
(1) Full automatic centralized lubrication;
(2) 、 Automatic cooling and lubrication of punch die
(3) Screen display and automatic reset of hydraulic overload protector;
(4) Equipped with pneumatic/hydraulic operated variable pressure plate clamp;
(5) An extra large worktable that can fully support large plates;
(6) Hydraulic CNC punch with high accuracy, high speed and low noise;
(7) Sliding worktable that can easily replace the mold and safely interlock;
(8) The polyurethane free ball device can prevent the material surface from scratching.
The processing technology of CNC punch has the following characteristics:
(1) High processing precision. The tolerance of hole edge distance is 0.2mm, and the tolerance of hole distance is 0.5mm/m.
(2) . Because there are many kinds of molds installed on the turret, the workpiece can be clamped once to complete all the processing contents immediately.
(3) The machine tool can process workpieces individually or batch process workpieces with G98 group command to improve productivity.
The workpiece reaches the bending process after going through two processes of blanking and stamping. CNC bending machine has the advantages that ordinary machine tools can not compare. For example, CASPRINI is produced in Italy and Siemens CNC system. The input method is manual programming. (1) Through the control panel, directly input the plate thickness, mold number, tensile strength, X-axis size, angle, workpiece length and stroke height to complete the preparation. (2) For some workpieces with complex shape and high precision requirements, 2D or 3D graphics, plate thickness and die number are input through the control panel. The function of man-machine dialogue is used to determine the bending sequence generation program. After the program is generated, it is stored in the program buffer area. If it is to be used in the future, it is stored in the machine tool memory. If the program needs to be used repeatedly, it should be copied out for backup through a special disk. The CNC bending machine usually has two towing racks in front and back. The CNC system controls the bending angle to determine the lifting height of the towing rack, which reduces the labor intensity of the operator. The common CNC bending machine has two servo motors to drive the X axis and Y axis of the machine tool. The detection component adopts a grating ruler, inductosyn, encoder, etc., which are usually installed on the lead screw of the machine tool. The detection feedback device converts the displacement of the lead screw into an electrical signal and feeds it back to the numerical control device. If there is an error of 0.02mm with the command value, the lead screw is controlled to make adjustments. The high-performance bending machine is equipped with a motor on both sides of the X axis, so that the X axis can be used to process beveled edges. A motor is installed on each shaft to process workpieces with different angles on both sides. A motor is added under the tailgate so that the tailgate can move up and down, which is more convenient for operation and processing. As the hydraulic system of the ordinary upward bending machine has been used on the machine tool for a long time, the lower die is bent. Therefore, the CNC bending machine is equipped with a hydraulic system under the machine tool. When the upper and lower dies work together, the system applies force to the lower die to reduce the deformation of the lower die and extend the service time of the lower die.
Features of CNC bending machine:
(1) After the program is established, it can work automatically or semi-automatically. The automatic cycle of the program enables the workpiece to be processed at one time, thus changing the inconvenience of large batch of workpieces and complex processes in semi-automatic processing.
(2) The numerical control system automatically calculates the oil pressure to avoid damage to the machine tool caused by overpressure.
(3) The introduction of 2D, 3D graphics input functions facilitates the processing of complex workpieces and improves the processing efficiency.
(4) The increase of various devices improves the processing technology and reduces the labor intensity of operators.
With the wide application of sheet metal machinery in aerospace, railway transportation, environmental protection equipment, air conditioning appliances, tobacco machinery, packaging and printing, engineering machinery, textile machinery and many other industries. The sheet metal processing also needs more high-tech workers to operate. Only good equipment and excellent staff can produce good products, making more excellent products made in China in the world.
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