What are the main points of manual clamping of the fixture? 

3 ways of clamp clamping

Manual clamping fixture that positions and clamps the workpiece by the workforce. When the manual fixture is operated, the extra time is extended, which relatively affects the production efficiency and is laborious and labor-intensive. On the other hand, the clamping force is uncertain when clamping the workpiece manually, which affects the machining accuracy.

However, the manual clamp is simple in design, convenient the manufacture, and low in cost, so there are still many applications. The manual clamp can adopt various mechanisms, which are highly adaptable.

2. Pneumatic clamping

The pneumatic clamping device uses compressed air as a power source to push the clamping mechanism to clamp the workpiece. At present, it is mainly used in floor-type electronic universal testing machines. The commonly used cylinder structures are piston type and film type. There are three types of piston cylinders: fixed type, swing type, and rotary type, according to the clamping method of the cylinder.

According to the working method, there are two one-way action and two-way action types. The most widely used is the double-acting fixed cylinder.

1. The pneumatic transmission has a fast response and quick action (the average action speed of the piston or cylinder is generally 0.5~1m∕s, and it can reach 10 m/s at high speed). Therefore, the additional time is short in production, and the production efficiency is high.

2. The transmission circuit is simple, convenient operation, and the system is easy to maintain.

3. The working environment has strong adaptability and can work reliably in environments with flammable, explosive, strong magnetism, radiation, humidity, vibration, and significant temperature changes, and is safe to use

4. With air as the medium, the energy supply is convenient. Discharge into the atmosphere after use, no need for pipes and recovery devices

5. The convenient centralized supply and long-distance compressed air transportation are convenient for centralized control, program control, and overload protection.

6. The medium is clean; leakage will not cause pollution

3. Hydraulic clamping

Hydraulic Clamping Device A fixture positions and clamps a workpiece with hydraulic pressure. They are mainly used in a hydraulic universal testing machines. As a kind of fixture, the hydraulic fixture uses standard hydraulic components. The working medium used is pressure oil. The mechanical parts are designed according to the characteristics of the machined parts and are organically assembled and connected.

Hydraulic clamping has the following advantages:

1) The transmission force is large, and the fixture structure is relatively small;

2) The oil is incompressible, the clamping is reliable, and the work is stable;

3) Low noise. Its disadvantage is that it must set up a unique hydraulic system, and the scope of application is limited.

4) Small-time constraints during clamping

5) Able to maintain constant clamping force

The fundamental explanation of the manual clamping method of the fixture

1. Wedge clamping mechanism.

The wedge clamping mechanism is one of the most basic clamping mechanisms. The screw clamping mechanism, the eccentric clamping mechanism, and the centering clamping mechanism are all deformations of the wedge clamping mechanism. The wedge clamp has the characteristics of simple connection, more powerful force increase, and better self-locking performance, so it is widely used.

1. Screw clamping mechanism.

The screw clamping mechanism has the advantages of simple structure, easy operation, large force increase ratio, and good self-locking performance. It is the most widely used clamping mechanism in manual clamping. The screw used in the screw clamping mechanism is equivalent to winding the wedge around the cylinder, and its clamping principle is the same as the wedge. But here, by rotating the screw, the height of the wedge around the cylinder changes to clamp the workpiece.

Because the screw clamping mechanism has a simple structure, easy manufacture, reliable clamping, large force increase ratio, and unlimited clamping stroke, it is widely used in manual clamping devices. The disadvantage of the screw clamping mechanism is the slow action. Some quick withdrawal devices are often used to improve their work efficiency.

1. Eccentric clamping mechanism.

The eccentric clamping mechanism is a fast-acting clamping mechanism with high working efficiency and is widely used in fixture design. There are two forms of commonly used eccentrics, namely: circular eccentricity and curved eccentricity. Curve eccentricity adopts Archimedes spiral or logarithmic spiral as profile curve.

Although the curve eccentricity has the advantages of uniform lift angle change, it is rarely used due to the complex manufacturing. In contrast, the circular eccentric is widely used in production due to its simple mechanism and easy manufacturing. The advantages of eccentric clamping are simple structure, convenient operation, and rapid action. The disadvantage is that the self-locking performance is poor, and the increased force is relatively small.

1. It has a hinged clamping mechanism.

The hinge clamping mechanism is a clamping mechanism that combines a hinge and a lever. This mechanism has the advantages of fast action, simple structure, relatively large expansion force, slight friction loss, and ease of changing the direction of action of the force, so it is widely used. However, its self-locking property is inferior, and it is generally not used alone.

It is mainly used in combination with pneumatic and hydraulic clamps in the exciting clamping mechanism, which can reduce the diameter of the cylinder and reduce the required power. Therefore, this mechanism is also called a force expansion mechanism. The hinge clamping mechanism is suitable for multi-point and multi-piece clamping and is widely used in pneumatic clamping.

5. Centering and centering clamping mechanism.

We often encounter workpieces whose design datum is based on the axis or pile center in machining. Must use a centering and centering clamping mechanism to make the positioning datum coincide with the design. The so-called "centering" means that when clamping the workpiece, the symmetrical center of the workpiece coincides with the center of the clamping mechanism of the fixture.

In the centering and clamping mechanism, the component contacting the workpiece is both a positioning element and a clamping element to complete the positioning and clamping process of the workpiece at the same time.

The centering clamping mechanism is a clamping mechanism that simultaneously realizes the centering, positioning, and clamping of the workpiece; that is, during the clamping process, it can keep the workpiece symmetrical relative to a particular axis or a specific symmetry plane.

The centering clamping mechanism is mainly used on occasions requiring accurate centering and alignment. In addition, since the positioning and clamping actions are performed simultaneously, they can shorten the additional time, can improve labor productivity, and are widely used in production at one time.

Centering and centering The clamping mechanism can achieve accurate centering and centering because it uses the constant velocity movement or elastic deformation of the positioning and clamping elements to eliminate the manufacture of the workpiece positioning reference surface.

Errors, so that these errors or deviations are equivalent to the centering or centering positions, which can be distributed evenly and symmetrically on the positioning base of the workpiece. Therefore, although there are many types of centering and centering clamping mechanisms, in terms of their respective working principles for centering and centering, they can be divided into two categories: centering and centering, that work on the principle of constant velocity movement.

Middle clamping mechanism; centering clamping mechanism that works on the principle of uniform elastic deformation.

1. Linkage clamping mechanism

In the design of the clamping mechanism, it is sometimes necessary to clamp several points on a workpiece or multiple workpieces simultaneously. At this time, to reduce the workpiece clamping time and simplify the structure, various linkage clamping mechanisms are often used. Such institutions require force from one place. Can clamp workpieces simultaneously in several places (or in several directions).