What is a Punch Press?

The punch is a stamping press. In national production, the stamping process has the advantages of saving material and energy compared with traditional machining, high efficiency, low technical requirements for operators, and the use of various mold applications to make products that cannot be achieved by machining, so It's used more and more widely.

The design principle of the punch is to convert the circular motion

Punches are widely used in stamping and forming of electronics, communications, computers, household appliances, furniture, vehicles, (automobiles, motorcycles, bicycles) hardware components and so on.

1. High rigidity and high precision frame, welded by steel plate, and

We divide according to driving force

The driving force of the slider can be divided into two types: mechanical and hydraulic. Therefore, the punching machine is divided into:

(1) Mechanical Power Press

(2) Hydraulic Press

For ordinary sheet metal stamping, most of them use mechanical punching machines. Depending on the liquid used, hydraulic presses are hydraulic presses and hydraulic presses. The majority of hydraulic presses are hydraulic presses, and hydraulic presses are mostly used for giant or special machines.

Classification by slider movement

There are single-action, double-action, and triple-action punches according to the movement of the slider. Currently, the most commonly used is a single-movement press with a slider. The double-action and triple-action punches are mainly used in the extension of automobile bodies and large-scale machining parts Processing, its quantity is very small.

Classification by slider drive mechanism

(1) Crank Press

A crank press that uses a crankshaft mechanism is called a crank press. Figure 1 shows a crank press, most of which are mechanical punches.

Use this body. The most common reason for using a crankshaft mechanism is that it is easy to make, can accurately determine the end position under the stroke, and the slider movement curve is basically used in various processes. Therefore, this type of punching is practically used for punching, bending, stretching, hot forging, warm forging, cold forging and almost all other punching processes.

(2) Crankless Press

Crankless presses are also called eccentric gear presses. Figure 2 shows eccentric gear presses. The function of the two structures of the crankshaft punch and the eccentric gear punch is measured. As shown in Table 2, the eccentric gear punch is superior to the crankshaft structure in terms of shaft rigidity, lubrication, appearance, and maintenance. The disadvantage is the higher price. When the stroke is long, the eccentric gear type punch is more favorable, and if the stroke of the special punching machine is short, the crankshaft punch is better. Therefore, the small machine and high-speed punching punch are also the fields of the crankshaft punch.

(3) Knuckle Press

Those who use the toggle mechanism on the slider drive are called toggle presses, as shown in Figure 3. This type of punch has a unique slider activity curve where the speed of the slider near the bottom dead point becomes extremely slow (as measured by the crankshaft punch), as shown in Figure 4. Moreover, the dead point position under the stroke is also correctly determined. Therefore, this punch is suitable for compression processing such as embossing and finishing, and is currently used most in cold forging.

(4) Friction Press

A press that uses friction transmission and a screw mechanism on a track drive is called a friction press. This kind of punch is most suitable for forging and crushing operations, and can also be used for bending, forming, stretching and other processing. It has a versatile function because it was inexpensive and was widely used before the war. Due to the inability to determine the end position below the stroke, poor machining accuracy, slow production speed, overload during control operation errors, and the use of skilled technology, it is gradually being eliminated.

(5) Screw Press

Those who use the screw mechanism on the slider drive mechanism are called screw punches (or screw punches).

(6) Rack press

The rack and pinion mechanism used on the slider drive mechanism is called a rack-type punch. Spiral presses have almost the same characteristics as rack-type punches, and their characteristics are roughly equivalent to those of hydraulic presses. Formerly used for squeezing bushings, chips and other items, squeezing, squeezing, packing, and extruding shells (thinning process in hot rooms), etc., but now they have been replaced by hydraulic presses unless they are extremely special Is no longer used.

(7) Link Press

A punch that uses various link mechanisms on the slider drive mechanism is called a link-type punch. The purpose of using the link mechanism is to keep the stretching speed within the limit during the extension process, while reducing the cycle of the process, and to reduce the speed change of the extension process to accelerate the approach stroke from The speed of the return stroke from the bottom dead center to the top dead point makes it shorter than the crankshaft press to improve productivity. This kind of punch has been used for the deep extension of cylindrical containers since ancient times. The bed surface is narrow, and it is used for the processing of automobile main panel and the bed surface is wide.

(8) Cam Press

A cam press that uses a cam mechanism on the slider drive mechanism is called a cam punch. The characteristic of this kind of punch is that it is made in the proper cam shape so as to easily obtain the desired slider movement curve. However, due to the nature of the cam mechanism, it is difficult to convey a large force, so this punching capacity is very small. ^[2]

Because the punch has the characteristics of high speed and high pressure, it must follow certain safety regulations for punching and forming.

1. Transmission parts exposed to the press must be fitted with a protective cover. It is forbidden to drive or test drive with the protective cover removed.

2. Before driving, check whether the main fastening screws are loose, the mold has no cracks, the operating mechanism, automatic stop device, clutch,

1.Gap between slide and guide

The adjustment of the gap between the slider and the guide is mainly for accuracy. When the adjustment is too tight, heat will be generated. Generally, each side of a small machine is 0.02 ~ 0.05mm, and each side of a large machine is 0.03 ~ 0.20mm.

2. Comprehensive gap

Comprehensive gap correction method: When the slider body in motion is touched by hand during production, when the slider reaches the bottom dead point, there is a vibration feeling, which indicates that the comprehensive gap is too large and needs to be adjusted in time.

3.Locking of the slider link

Due to long-term use or overload, the connecting rod will loosen. This state is generally considered to be an overload; there is also an oil leaching at the joint part may be an overload; this state must be adjusted in time. The tightness of the female, because it is related to safety issues.

4.Brake and clutch maintenance

The brake and clutch of the stamping machine are important parts for the safe operation of the stamping machine. It is the cause of major safety accidents. Therefore, it is necessary to understand its basic structure, and to confirm its safety performance and find abnormal conditions (such as: The slider cannot stop at the specified position, there are abnormal sounds, abnormal vibrations, sluggish movement of the slider, etc. during operation) Report the maintenance in time.

In addition, maintenance personnel should also pay attention to if the gap between the brake and clutch friction plates is too large: the increase in the amount of compressed air, the slider of the stamping machine crawls, and in severe cases, the slider will continuously operate once. This is absolutely not allowed to happen. Then if the adjustment gap is too small, the friction plates of the brake and clutch will produce friction sounds, heat, and motor current rise, etc., and it will also cause damage to the return spring. (Normal clearance is 1.5 ~ 3.0mm).

5, break away

The detachment usually occurs at the bottom dead center. When the upper and lower molds are closed, the slider cannot run normally. At this time, you can make the motor run in reverse and increase the pressure of the air compressor. Turn the operation selector to the "Inching" state, and pull the slider to the top dead point in stages.

6. Correction of loose bolts

It includes the bolts of the auxiliary equipment of the machine tool, which must be confirmed regularly, especially for some high-speed and frequent presses, because the vibration of these machine tools is relatively easy to loosen the bolts. Once the bolts are loose, if not corrected in time, it will cause some unexpected safety accidents.

7. Inspection of oil supply device

Burning and biting often occur in the running part of the machine when the oil supply is not timely. Therefore, the inspection of the oiling part must be carried out. It includes oil cups, oil tanks, oil pipes, filters, oil seals, etc. The "running, dripping, dripping, leaking, blocking" phenomena must be dealt with in a timely manner.

8. Inspection of compressed air

Leakage in the compressed air line of the machine tool will cause a low pressure and affect the operation of the machine tool, so it must be repaired in time.

In addition, the water content of compressed air should also be controlled (air filtering, drying and dehydration equipment can be added), which is a major cause of slow operation and corrosion of machine tools such as solenoid valves and cylinders.

9. Regularly check the accuracy of the punch

The accuracy of the punch will directly affect the service life of the mold and the processing accuracy of the product. However, the accuracy of the machine tool deteriorates with time, so regular precision inspections must be performed and problems found to be repaired in time to ensure that the machine tool has a relatively accurate accuracy and thus the accuracy of the products produced. ^[2]