Punch Machine Operation Instructions: Standard Document

1. Purpose

In order to standardize the safe operation of stamping and forming operations in the petrochemical product manufacturing process, ensure the quality of processed products, and extend the service life of equipment, this operation instruction is formulated and must be strictly followed by the company’s ordinary punch operators.

2. Scope of application:

It is applicable to the operation guidance for blanking, punching and forming of low-carbon steel plate, low-alloy steel plate and stainless steel plate in the stamping and forming operation of the petrochemical product manufacturing process.

3. Referenced standards/regulations/documents

None

4. Responsibilities

4.1 The operators of ordinary punching machines in the production workshop must strictly observe the safety operation procedures and wear labor protection articles as required.

4.2 The Technology Department shall prepare production drawings and process cards according to the production plan, supervise and inspect the implementation of the punch operation instructions and process disciplines, and publish them timely.

4.3 The operator shall carry out operation, self inspection, quality assurance, equipment maintenance and report filling according to the process card.  

4.4 The inspectors of the Quality Control Department are responsible for the 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 production plan decomposition and progress tracking.

5. Operating procedures

5.1 Stamping process

5.1.1 Stamping process refers to the processing method of workpieces with certain 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, which can be used to process metal sheets, bars and a variety of non-metallic materials.

As the processing is usually carried out at room temperature, it is also called cold stamping.

5.1.2 Features of stamping process

1) It is a kind of workpiece with complex shape and difficult to process by other processing methods, such as thin shell parts, which can be obtained by cold stamping processing.

The dimensional accuracy of cold stamping parts is guaranteed by the die, so the dimensions are stable and the interchangeability is good.

2) High material utilization rate, light weight, good rigidity, high strength and less energy consumption during stamping.

Therefore, the cost of the workpiece is low.

3) Simple operation, low labor intensity, easy to realize mechanization and automation, and high productivity.

4) The die structure used in stamping processing is generally complex, with long production cycle and high cost.

5.1.3 Basic requirements for stamping materials

1) The materials used for stamping shall not only meet the technical requirements of product design, but also meet the requirements of stamping process and processing requirements after stamping (such as cutting, electroplating, welding, etc.).

2) Requirements for material properties of stamping forming:

a. For the forming process, in order to facilitate the stamping deformation and improve the quality of the parts, the materials should have: good plasticity (uniform elongation δb height), yield ratio (σs/ σb) small, large plate thickness directivity coefficient, small plate plane directivity coefficient, and the ratio of material yield strength to elastic modulus( σS/E) small.

b. For the separation process, the material does not need to have good plasticity, but it should have certain plasticity.

The better the plasticity, the harder it is to separate.

3) Requirements for material thickness tolerance:

The thickness tolerance of materials shall comply with national standards.

Because a certain die clearance is applicable to a certain thickness of the material, the material thickness tolerance is too large, which not only directly affects the quality of the parts, but also may lead to damage to the die and punch.

4) Requirements for material surface quality

a. The surface of the material shall be smooth and flat, free of delamination, mechanical property damage, rust spot, oxide skin and other attachments.

b. The materials with good surface quality are not easy to crack and scratch the mold during stamping, and the surface quality of the workpiece is also good.

5.2 Classification of stamping process:

5.2.1 Fracture separation process:

Fracture separation process is a process to separate stamping parts from sheet metal along a certain contour line in the stamping process, such as blanking, punching, trimming, cutting, sectioning, etc.

1) Blanking: 

Blanking is performed on the blank of the flat plate along the closed contour, and the rest is scrap.

Blanking is often used in the first process of the workpiece (see Fig. 1).

Punch Machine Operation Instructions: Standard Document 1

Fig. 1 Schematic Diagram of Blanking

2) Punching: 

Punching refers to punching and blanking of holes of various shapes with blanking parts or other shaped parts as process parts (see Fig. 2).

Punch Machine Operation Instructions: Standard Document 2

Fig. 2 Punching Diagram

3) Trimming: 

Trimming refers to blanking the edge of the formed part to obtain the required shape and size of the workpiece (see Fig. 3).

Punch Machine Operation Instructions: Standard Document 3

Fig. 3 Schematic Diagram of Trimming

4) Notching: 

As shown in Fig. 4, the local material is cut and bent to a certain angle on the material, but not completely separated from the main body, which is called notch or punching forming.

Punch Machine Operation Instructions: Standard Document 4

Fig. 4 Schematic Diagram of Notch

5) Sectioning: 

As shown in Fig. 5, the formed solid shape process piece is divided into two pieces, which is called sectioning.

Punch Machine Operation Instructions: Standard Document 5

Fig. 5 Sectioning Diagram

5.2.2 Plastic forming process:

Plastic forming process refers to the plastic deformation of materials without cracking, so as to obtain parts with certain shape, size and accuracy requirements, such as bending, deep drawing, bulging, flanging, necking, crimping, etc.

1) Bending: 

As shown in Fig. 6, the plate blank is bent to a certain angle or the bent part is further formed. Such as: bending, curling, twisting, etc.

Punch Machine Operation Instructions: Standard Document 6

Fig. 6 Bending Diagram

2) Stretching: 

As shown in Fig. 7, the flat blank is rolled into a hollow piece, or the hollow blank is further deformed.

Punch Machine Operation Instructions: Standard Document 7

Fig. 7 Stretching Diagram

3) Bulging: 

As shown in Fig. 8, radial pressure is applied from the inside of the hollow piece to enlarge the local diameter.

For example: stainless steel teapots, cups, etc.

Punch Machine Operation Instructions: Standard Document 8

Fig. 8 Bulging Diagram

4) Necking:

As shown in Fig. 9, apply pressure on the outside of the hollow part to reduce the local diameter, such as stainless steel cup cover, tank products, etc.

Punch Machine Operation Instructions: Standard Document 9

Fig. 9 Schematic Diagram of Necking

5) Rolling: 

As shown in Fig. 10, use the rolling die to roll the edge of the hollow part outward into an arc edge, for example: can products.

Punch Machine Operation Instructions: Standard Document 10

Fig. 10 Schematic Diagram of Rolling Circle

5.3 Operation process (see Fig. 11):

(1) Operation preparation: check equipment, mold and fixture

(2) Picking materials, tools and measuring tools according to the MO

(3) Calibration of tools and measuring tools, and self-inspection of materials

(4) Equipment commissioning

(5) Processing operation and first inspection

(6) Submit for inspection

(7) End of operation: reset the operating handle and shut down the system

5.4 Operation specification

5.4.1 Operation preparation:

1) Clean up the surrounding environment of the press to ensure that it is clean and tidy for normal operation.

2) Check the lubrication of all parts and make sure that all lubricating points are fully lubricated.

3) Check whether the mold is installed correctly and reliably, and check whether there are sundries in the mold to avoid product crushing and mold damage caused by sundries.

4) Check whether the power switch of the feeder is turned on to avoid dislocation due to non feeding.

5) The flywheel must be disconnected from the clutch to start the motor.

6) When starting the motor, it must be noted whether the flywheel rotation direction is the same as the rotation sign.

If not, cut off the power supply immediately for inspection and readjust the power supply sequence.

7) Make the press travel for several times, check the operation of brake, clutch and horse operator, and conduct normal operation after checking that the punch is normal.

5.4.2 Operation method

1) Start the punch according to the startup method in the Punch Operation Manual, and turn on the switch of the blow pipe to avoid the product from being blown away and causing the product to be stacked.

2) Test punch several workpieces manually for self inspection, and normal operation can only be carried out after being confirmed by the full-time inspector.

Open the counter for continuous punching and check the appearance and size of the punched product once every 5-10 minutes: pressing, small holes, deformation, burrs, oil stains and other undesirable conditions and the conformity of main dimensions.

3) In normal continuous stamping, press and hold the red brake button with one hand, look squarely at the mold and the outlet, sit upright and concentrate, and never talk or joke with each other to avoid damage to the mold or disqualification due to misplacement and drop of punches.

4) The normal stamping shall record in detail the items that the stamping personnel should fill in, and record the production quantity of each roll or hour on the Personal Production Daily Report.

5) In case of any abnormality of machine tool products found during normal stamping, it is necessary to immediately stop the machine and report to the superior for timely treatment, and assist the quality inspector to distinguish and isolate the defective products.

6) After punching, the working area environment (empty boxes, finished boxes and stools are placed in order) shall be sorted out, the punch and blow pipe shall be closed in the correct order, and all power switches and oil duct switches shall be closed before leaving the work post.

7) In case of adjustment and repair of molds, punches and feeders during operation, the first product after adjustment and repair must be submitted to the full-time inspector for confirmation and the First Piece List shall be issued before continuing production.

8) Parts produced during normal stamping production in case of abnormal shutdown (power failure, insufficient air pressure, etc.) must be scrapped.

In case of re production, it must be inspected by the Quality Department before continuing production.

9) Add lubricating oil to each lubricating point regularly, and oil the inner and outer guide pillars of the mold every 4 hours.

5.5 Judgment, treatment and preventive measures for common defects of stamping parts:

5.5.1 For the outer panel, the requirements are high and there shall be no obvious defects.

5.5.2 The inner plate shall be free from cracks and hidden cracks.

For deep drawing parts, first check whether the pressure points are clear, then check whether there are hidden cracks, and then touch them with your hand and push them with an oilstone.

1) Bumpy

a. Judgment method: touch with your hand, push with an oilstone, and look with your eyes.

Pushing with an oilstone is recommended. Highlights are bulges, and dark spots are depressions.

b. Cause: In case of unevenness, check whether there is sand and other foreign matters in the mold;

c. Treatment: If there is sand, wipe the mold with mold wiping paper;

2) Cracking (concealed cracking)

a. Judgment method: Use eyes to check the corners of the drawing parts and other places with large material deformation, and turn over the reverse side to check.

b. Cause: It may be that the die is strained and the blank holder force is too large.

c. Treatment method: check whether the workpiece is seriously strained, and properly reduce the side force.

3) Wrinkle

a. Judgment method: look with eyes;

b. Cause: small blank holder force;

c. Treatment: appropriately increase the blank holder force.

4) Burrs

a. Judgment method: Look with your eyes.

b. Cause: The clearance between male and female dies is large.

c. Treatment method: mold repair.

5) Hole deflection

a. Judgment method: check with upper inspection tool and compare with the sample.

b. Cause: The workpiece is not placed properly, and the mold positioning device is faulty.

c. Treatment method: If the hole is still deviated after the workpiece is straightened, report to the shift leader and notify mold repair.

6) Pinhole

a. Judgment method: compare with the sample.

b. Cause: The punch is broken.

c. Treatment: stop production immediately, report to the shift leader immediately, and notify mold repair.

7) Hole deformation

a. Judgment method: Look with your eyes.

b. Cause: The punch is worn.

c. Treatment method: report to the shift leader and notify mold repair if slight oiling and severe oiling still have deformation.

8) The drawing is not in place.

a. Judgment method: check whether the pressure point is clear.

b. Cause: The main pressure is too low.

c. Treatment: appropriately increase the main pressure.

9) Poor folding

a. Judgment method: compare with the sample

b. Cause: The parts are not placed properly, and the positioning device is faulty.

c. Handling method: place the workpiece properly. If it is still defective, report to the shift leader and notify the mold repair personnel to repair the mold.

10) Imprint

a. Judgment method: Look with your eyes.

b. Cause: There are granular impurities on the working surface of the upper mold.

c. Treatment: Wipe the upper mold clean.

11) Strain

a. Judgment method: Look with your eyes.

b. Cause: The working face of the die is worn and the hardness of the die is not enough.

c. Treatment method: mold repair.

12) Sand grain

a. Judgment method: push with an oilstone.

b. Cause: The material or mold surface is not clean.

c. Treatment: check the materials or wipe the mold surface clean.

13) Bump and scratch

a. Judgment method: Look with your eyes.

b. Cause: The incoming or outgoing materials touch hard objects such as molds.

c. Treatment: Be careful when feeding and discharging materials, handle the products with care, and increase the closing height of the mold if necessary.

6. Operation precautions

6.1 Environmental considerations

6.1.1 When it takes more than 10 minutes to leave the machine, be sure to turn off the power to save electricity.

6.1.2 Oily rags or cotton yarn during operation and machine maintenance must be placed in the designated recycling place.  

6.1.3 The waste produced during operation must be placed in the designated waste area, and it is strictly prohibited to throw it anywhere.

6.1.4 Oil used for operation and machine maintenance must be placed separately and recycled uniformly.

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 It is forbidden to smoke around oil and gas storage tanks to prevent fire or explosion.  

6.2.3 During the operation of the machine, the motor 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 prevent industrial accidents.

6.2.5 The stamping operation shall be highly concentrated to ensure that the products and molds are normal.  

6.2.6 During the operation of the punch, it is forbidden to put your hand into the mold or beside it to ensure your health and safety.

6.2.7 During normal stamping, it is strictly forbidden to work with two or three people on the same machine.

Pay special attention to the self inspection action of taking products and the action of picking up products in the receiving chute to ensure personal safety.

6.2.8 The equipment shall be stopped immediately if it is found abnormal.

6.2.9 Disconnect the flywheel from the clutch and turn off the power after work.

6.2.10 Wipe and clean the press and apply oil on the unpainted machined surface.

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