Technical specifications of electronic universal testing machine jaws

1. Wedge-shaped jaws and flat push jawsElectronic universal testing machinemodel.

The picture shows the electronic universal testing machine product commonly used in the domestic market. Its jaws are made of wedge-shaped jaws, which are self-locking. During the stretching process, the sample is reliably clamped by self-locking force. The hydraulic lifting device provided only provides the hydraulic pressure required for operation. .

The flat-push jaw electronic universal testing machine is generally used in single-space electronic universal testing machine. The clamping of the sample is forced by the clamping force of the flat push jaw. Therefore, its structure is usually achieved by a high-pressure synchronous oil cylinder, which requires the pumping station system to provide high-pressure oil (usually 30MPa, and foreign countries are generally 70MPa). To realize this technology, such as hydraulic cylinder synchronization technology, high-pressure technology, etc., it is difficult to make production, so this model is usually costly. (This type of product is called flat push type.)

2. Comparison of the two models. Flat push type: mainly popular in European countries, its advantage is that it can use the forced clamping ability of the jaw to perform bidirectional zero-crossing tensile pressure test of the material. The test efficiency of the flat push type is relatively high, and the disadvantage is that the overall structure is relatively large. The wedge type can be made very small, and its small jaws are widely used in electronic tension electronic universal testing machines using pneumatic and other technologies.

The wedge type is generally a double-space structure, but it can also be made into a single space.

The flat push machine is generally used in single-space electronic universal testing machines. The design and consideration of its compressed part are generally insufficient, and are particularly suitable for the field where tensile is the main test object.

Wedge type: clamping is achieved using the self-locking principle, and the process route is simple, so the whole machine is usually low in cost. The flat push type also needs to provide independent high-pressure oil, and the synchronization technology of the oil cylinder also consumes costs, so the whole machine is expensive.

There are many things to discuss about the advantages and disadvantages of the two models and are closely related to the industry. I won’t describe it here.

3. Discussion on several misunderstandings and debates.

1) Misunderstanding 1: The flat push jaw represents the advanced technology.

Those who put forward this view are generally product users. But the electronic universal testing machine industry has never agreed with this view.

2) The first half of this view is theoretically untenable. It is noted that wedge-shaped jaws have natural neutral geometric properties, and their neutralization performance is only related to the processing accuracy of the equipment. The flat push type, after clamping the sample, the neutrality depends on the synchronization of the two flat push cylinders. The initial stress problem is indeed supported by the flat push type, but the actual situation is not ideal.

3) Dispute 1: Pushing the jaw flat is a development trend.

There is a lot of debate in the electronic universal testing machine world. In terms of the zero-crossing tension performance of the flat push jaw, since the MTS' dynamic electronic universal testing machine solved the forced clamping of the wedge-type jaw, the disadvantage of the flat push type has become prominent (large size, high cost and slow efficiency).

4) Dispute 2: The flat push jaw is particularly suitable for fully automatic electronic universal testing machines with robots.

This electronic universal testing machine usually refers to a fully automatic electronic universal testing machine that is automatically loaded and unloaded and clamped with automatic extensometers.

4. Summary.

1) The flat push type is a new jaw structure that has just started in China, and the technological maturity needs to be improved.

2) There is no more advanced problem between wedge type and flat push type. Each has its own advantages and characteristics.

3) The flat push type is mainly a single-space electronic universal testing machine. The wedge type can be either single-space or double-space. This conclusion is valid.

4) There has always been uncertainty in some debates, and development will eventually solve this problem.