1. Purpose
To standardize the safe operation of stamping and forming processes in the petrochemical manufacturing process, ensure the quality of processed products and extend the service life of equipment, this operating instruction has been formulated. It must be strictly followed by the company's ordinary punch operators.
2. Scope of application:
This applies to the operational guidelines for stamping, punching and forming low carbon steel, low alloy steel and stainless steel sheets in the stamping and forming processes of the petrochemical manufacturing industry.
3. Standards/regulations/referenced documents
None
4. Responsibilities
4.1 Operators of common punching machines in the production workshop must strictly observe safety operating procedures and wear the required labor protection articles.
4.2 The Technology Department must prepare production drawings and process sheets in accordance with the production plan. They must also supervise and inspect the implementation of punch operating instructions and process disciplines, and publish them in a timely manner.
4.3 The operator must carry out operations, self-inspection, quality assurance, equipment maintenance and completion of reports according to the process sheet.
4.4 Inspectors of the Quality Control Department are responsible for first article confirmation, patrol inspection, quality inspection of process products, and supervision of the implementation of process parameters.
4.5 The production workshop is responsible for breaking down the production plan and monitoring progress.
5. Operating Procedures
5.1 Stamping process
5.1.1 The stamping process is a method of processing workpieces with specific size, shape and performance by applying external force to the blank through the mold to cause plastic deformation or separation.
Stamping technology has a wide range of applications and can be used to process metal sheets, bars and various non-metallic materials. As the process is typically carried out at room temperature, it is also known as cold stamping.
5.1.2 Characteristics of the stamping process:
1）It can produce parts with complex shapes that are difficult to obtain using other processing methods. For example, thin shell parts can be obtained by cold stamping processing. The dimensional accuracy of cold stamped parts is guaranteed by the die, resulting in stable dimensions and good interchangeability.
2) Stamping has a high material utilization rate, resulting in light, rigid and strong parts with low energy consumption during the stamping process. Consequently, the cost of the part is low.
3）This operation is simple and has low labor intensity. It is also easy to carry out mechanization and automation, which leads to high productivity.
4) The die structure used in stamping processing is generally complex, which results in a long production cycle and high cost.
5.1.3 Basic Requirements for Stamping Materials
1) Materials used for stamping must not only meet the technical requirements of product design, but also meet the requirements of the stamping process and the processing requirements after stamping such as cutting, electroplating and welding.
2) Requirements for stamping material properties:
The. For the forming process, to facilitate stamping deformation and improve the quality of parts, materials must have good plasticity (uniform elongation δb height), a small yield ratio (σs/ σb), a large thickness directivity coefficient of the plate, a small directivity coefficient of the plate plane and a small proportion between the flow resistance of the material and the modulus of elasticity (σS/E).
B. For the separation process, the material does not need to have excellent plasticity, but it must have a certain level of plasticity. The more difficult it is to separate, the better the plasticity should be.
3) Requirements for material thickness tolerance:
The thickness tolerance of the material must be in accordance with national standards. If the material thickness tolerance is too large, it may directly affect the quality of the parts and also cause damage to the die and punch. This is because a certain die gap is suitable for a specific material thickness.
4) Requirements for material surface quality:
The. The surface of the material must be smooth and flat, free from delamination, mechanical damage to property, rust stains, oxide layer and any other accessories.
B. Materials with good surface quality are less likely to crack or scratch the mold during stamping. This results in a high-quality surface quality of the workpiece.
5.2 Classification of the stamping process:
5.2.1 Fracture separation process:
The fracture separation process is used to separate stamped parts from sheet metal along a specific contour line during the stamping process. This process can be carried out using various techniques, such as stamping, punching, trimming, cutting, sectioning and much more.
1) Suppression:
Blanking is the process of cutting a flat plate along a closed contour, and the remaining material is considered scrap. This method is commonly used as an initial step in modeling a part, as shown in Figure 1.
Fig. 1 Blanking schematic diagram
2) Drilling:
“Punching” refers to the process of creating holes of various shapes using blanks or other shaped parts (see Fig. 2). This process may include punching and erasing.
Fig. 2 Punching Diagram
3) Cut:
Trimming involves removing excess material from the edge of the molded part to obtain the desired shape and size of the workpiece (see Fig. 3).
Fig. 3 Schematic cutting diagram
4) Notch:
As depicted in Figure 4, the local material is cut and bent at a specific angle onto the material without being completely separated from the main body. This process is commonly known as notch or punch formation.
Fig. 4 Schematic diagram of the notch
5) Sectioning:
The process of creating a solid shape in Fig. 5 involves dividing the part into two sections, which is called sectioning.
Fig. 5 Sectioning Diagram
5.2.2 Plastic forming process:
Plastic forming processes involve reshaping materials without causing cracks in order to create parts with specific shapes, sizes and precision requirements. Examples of plastic forming processes include bending, deep drawing, bulging, flanging, throttling, and crimping.
1) Flexion:
The diagram in Figure 6 illustrates the process of bending a blank plate at a specific angle or further shaping the bent section through techniques such as bending, curling, twisting, and so on.
Fig. 6 Bending Diagram
2) Stretching:
As depicted in Figure 7, the flat blank goes through a rolling process to form a hollow part, or the hollow blank is subjected to additional deformation.
Fig. 7 Stretching diagram
3) Bulging:
As depicted in Figure 8, the hollow part is subjected to internal radial pressure to increase its local diameter. This technique is commonly used in the manufacture of teapots, cups and other similar stainless steel products.
Fig. 8 Bulging diagram
4) Tightening:
As illustrated in Figure 9, to decrease the local diameter of hollow objects such as stainless steel cup lids, tank products, etc., apply pressure to the outside.
Fig. 9 Schematic diagram of narrowing
5) Bearing:
As illustrated in Figure 10, use a rolling die to bend the edge of the hollow object outward in an arc shape. This method is commonly used for canned products.
Fig. 10 Schematic diagram of the rolling circle
5.3 Operation process (see Fig. 11):
(1) Prepare for operation by checking equipment, molds and accessories.
(2) Select materials, tools and measuring tools according to the manufacturing order (MO).
(3) Calibrate measuring tools and equipment and perform self-inspection of materials.
(4) Commission the equipment.
(5) Start processing operations and carry out the first inspection.
(6) Send for inspection.
(7) At the end of the operation, reset the operation lever and turn off the system.
5.4 Operation specification
5.4.1 Operation preparation:
1）Clean the area around the press to ensure it is tidy for normal operation.
2) Check the lubrication of all parts and ensure that all lubrication points are fully lubricated.
3) Check the correct and reliable installation of the mold and make sure there is no debris inside to avoid damage to the product and the mold.
4) Make sure the feeder power switch is turned on to avoid shifting due to non-power.
5）Disconnect the clutch flywheel to start the engine.
6）When starting the engine, make sure the steering wheel rotation direction matches the rotation signal. If not, immediately turn off the power supply for inspection and adjust the power supply sequence.
7) Move the press several times, check the operation of the brake, clutch and horse operator, and start normal operation after checking whether the punch is working properly.
5.4.2 Operation method
1）Follow the start-up method described in the Drilling Operation Manual to start the drilling process. Turn on the blow tube switch to prevent the product from being blown, which may result in stacking and damage.
2）Manually test the perforation of various workpieces for self-inspection purposes. Full-time inspectors must confirm normal operation before proceeding.
3) During normal continuous stamping, hold the red brake button with one hand, sit up straight and concentrate on the die and exit. Avoid talking or playing with other people to avoid damage to the mold or disqualification due to loss or falling blows. Check the appearance, size, pressing, small holes, deformations, burrs, oil stains and compliance of the main dimensions of the drilled product every 5-10 minutes.
4）Record detailed information in the Personal Production Daily Report during normal stamping, including the production quantity of each roll or hour. Stamping personnel must fill in the required fields accurately.
5) If any abnormalities are found in the machine tool products during normal stamping, it is essential to stop the machine immediately and report to the superior for timely treatment. In addition, the quality inspector must also assist in distinguishing and isolating defective products.
6) After drilling, the working area environment should be organized, including empty boxes, finished boxes and benches. The punch and blow tube must be closed in the correct order and all power switches and oil ducts must be turned off before leaving the workstation.
7）If molds, punches and feeders need adjustment or repair during operation, the first product produced after correction must be submitted to the full-time inspector for confirmation. Additionally, the First Piece List must be issued before production continues.
8）If an abnormal shutdown occurs during normal stamping production due to power failure, insufficient air pressure, etc., the parts produced during this period must be discarded. If reproduction is necessary, it must be inspected by the Quality Department before continuing production.
9) Regularly add lubricating oil to each lubrication point and lubricate the internal and external guide pillars of the mold every four hours.
5.5 Judgment, treatment and preventive measures for common defects of stamped parts:
5.5.1 The external panel requires high standards and no visible defects are permitted.
5.5.2 The internal plate must be free from cracks, including hidden ones.
When inspecting deep drawing parts, start by checking the pressure points for clarity. Then look for hidden cracks. Finally, touch and push the pieces with an oil stone.
1) Accident
The. Assessment method: Use your hands to touch, push with an oil stone and visually inspect.
It is recommended to use the oiled stone pushing method. Bumps should be highlighted, while depressions should appear as dark spots.
B. Cause: If there are irregularities, check whether there is sand or other foreign matter in the mold.
w. Treatment: If there is sand, clean the mold with mold cleaning paper.
2) Cracks (hidden cracks)
The. Judging method: Use your eyes to check the corners of the drawing parts and other places with large material deformation, and turn the back side over to check.
B. Cause: It may be that the die is stressed and the support force of the blank is too great.
w. Treatment method: check whether the workpiece is seriously stressed and appropriately reduce the lateral force.
3) Wrinkles
The. Judging method: look with your eyes;
B. Cause: small force on the blank holder;
w. Treatment: appropriately increase the strength of the blank holder.
4) Burrs
The. Judgment method: look with your eyes.
B. Cause: The gap between male and female dies is large.
w. Treatment method: mold repair.
5) Hole deflection
The. Judgment method: check with the upper inspection tool and compare with the sample.
B. Cause: The workpiece is not positioned correctly and the mold positioning device is defective.
w. Treatment method: If the hole is still deviated after straightening the workpiece, inform the shift leader and notify mold repair.
6) Hole
The. Judgment method: compare with the sample.
B. Cause: The punch is broken.
w. Treatment: Stop production immediately, immediately report to the shift leader and notify mold repair.
7) Hole deformation
The. Judgment method: look with your eyes.
B. Cause: The punch is worn out.
w. Treatment method: inform the shift leader and notify mold repair if light lubrication and severe lubrication still show deformation.
8) The drawing is not in place .
The. Judgment method: check whether the pressure point is clear.
B. Cause: Main pressure is too low.
w. Treatment: adequately increase the main pressure.
9) Poor folding
The. Judgment method: compare with the sample
B. Cause: The parts are not placed correctly and the positioning device is defective.
w. Handling method: place the workpiece correctly. If it is still defective, inform the shift leader and notify the mold repair personnel to repair the mold.
10) Printing
The. Judgment method: look with your eyes.
B. Cause: There are granular impurities on the working surface of the upper mold.
w. Treatment: Clean the upper mold.
11) Voltage
The. Judgment method: look with your eyes.
B. Cause: The working face of the die is worn and the hardness of the die is not sufficient.
w. Treatment method: mold repair.
12) Grain of sand
The. Judging method: push with an oil stone.
B. Cause: The material or mold surface is not clean.
w. Treatment: check the materials or clean the mold surface.
13) Hitting and scratching
The. Judgment method: look with your eyes.
B. Cause: Incoming or outgoing materials touch hard objects such as molds.
w. Treatment: Be careful when feeding and unloading materials, handle products carefully and increase the mold closing height if necessary.
6. Operation Precautions
6.1 Environmental considerations
6.1.1 When it takes more than 10 minutes to get out of the machine, be sure to turn off the power to save electricity.
6.1.2 Oily cloths or cotton threads during operation and maintenance of the machine must be placed in a designated place for recycling.
6.1.3 Waste produced during operation must be placed in the designated waste area, and it is strictly prohibited to throw it anywhere.
6.1.4 The oil used for operation and maintenance of the machine must be placed separately and recycled evenly.
6.2 Safety precautions
6.2.1 Non-electricians are not allowed to open the distribution box and touch the circuit without permission to avoid electric shock.
6.2.2 Smoking is prohibited around oil and gas storage tanks to prevent fire or explosion.
6.2.3 During machine operation, the engine belt must be equipped with a protective cover. The safety protection device cannot be removed arbitrarily.
6.2.4 Press the start button with both hands to avoid industrial accidents.
6.2.5 The stamping operation must be highly concentrated to ensure that the products and molds are normal.
6.2.6 During the operation of the punch, it is prohibited to place your hand inside or next to the mold to guarantee your health and safety.
6.2.7 During normal stamping, it is strictly prohibited to work with two or three people on the same machine.
Pay special attention to the self-inspection action of product withdrawal and the action of collecting products from the receiving chute to ensure personal safety.
6.2.8 The equipment must be stopped immediately if an abnormality is detected.
6.2.9 Disconnect the clutch flywheel and turn off the power after work.
6.2.10 Clean and clean the press and apply oil to the unpainted machined surface.
