How much difference in production power? The conclusion is that the fixture used in the CNC machine tool is not suitable, which makes the production power of the CNC machine tool drop drastically.
How to improve the utilization of CNC machine tools? After skill analysis, there is a great connection between the use of fixtures. According to the response of the gold powder, there are often CNC machine tools in the operation because the fixture selection is unreasonable or improperly applied, but presents the phenomenon of “women's work”; from another point of view, there is a lot of articles on the selection and application of CNC machine tool fixtures. Do it because it contains considerable potential economic benefits.
Correct selection of fixture types is the basis for efficient machining
At present, machining can be divided into two categories according to the production batch: one is single, multiple, small (small batch production); the other is small, large batch (referred to as mass production). In the meantime, the former accounts for 70-80% of the total value of mechanical processing, and is the main body of machining.
Suitable for CNC machine tool fixtures produced in small batches
Small batch production cycle = production (preparation / waiting) time + workpiece processing time Because the "workpiece processing time" is small in small batch production, the length of "production (preparation / waiting)" has a crucial influence on the processing cycle. . In order to improve the production power, we must find ways to shorten the production (preparation / waiting) moments.
The following three types of small-volume production of CNC machine tool fixtures that can be prioritized are recommended:
Combined fixture
The combination fixture is also called “building block fixture”. It consists of a series of machine tool fixture components with standardized planning, different functions and different standard scales. The customer can quickly assemble the same according to the processing requirements. Various types of machine tool fixtures. Because the combination fixture eliminates the need to plan and manufacture special fixtures, it greatly shortens the production preparation time, thus effectively shortening the small batch production cycle, that is, improving the production power. In addition, the combined fixture also has the advantages of high positioning accuracy, large clamping flexibility, repeated use of the cycle, production of energy-saving materials, and low cost of use. Therefore, small batch processing, especially when the shape of the product is more complicated, can give priority to the use of combined fixtures.
Fine combination pliers
The fine combination pliers are actually “combined parts” in the combined fixtures. Compared with other combination fixture components, they are more versatile, more standardized, more compact and more secure. They are widely available on a global scale. Use. The fine combination pliers have the advantages of rapid device (opening) and rapid clamping, so that the production preparation time can be shortened and the small batch production power can be improved. At present, the precision combination clamps commonly used in the world are usually within 1000mm, and the clamping force is usually within 5000Kgf.
The demand is that the fine combination pliers mentioned here are not old-fashioned machines and vise. The old-fashioned machine plus vise has a single function, low production precision, can not be used in groups, and has short service life. It is not suitable for CNC machine tools and processing bases. Apply on.
The fine combination pliers mentioned here are a series of new flat-nose pliers which are originated from the developed countries of Europe and the United States and specially designed for the characteristics of CNC machine tools and processing bases. These products have large clamping flexibility, high positioning accuracy and clamping diseases. Speed, can be used in groups and other features, especially suitable for CNC machine tools, processing base applications.
Electric permanent magnet fixture
The electric permanent magnet fixture is a new type of fixture which is planned by using the new permanent magnet data such as neodymium iron boron as the magnetic source and using the modern magnetic circuit principle. Many machining internships indicate that the electric permanent magnet fixture can greatly improve the inductive processing efficiency of CNC machine tools and processing bases.
The clamping and loosening process of the electric permanent magnet fixture takes only about 1 second, which greatly shortens the clamping time; the positioning component and the clamping component of the conventional machine tool fixture occupy a large space, and the electric permanent magnet fixture does not have such space. Compared with conventional machine tool fixtures, the assembly of electric permanent magnet fixtures is larger, which is beneficial to make full use of the operating table and machining stroke of CNC machine tools, which is beneficial to improve the inductive machining efficiency of CNC machine tools. The suction force of the electric permanent magnet clamp is usually 15~18Kgf/cm2, so it is necessary to ensure that the suction force (clamping force) satisfies the resistance to the cutting force. Under normal circumstances, the adsorption area should not be less than 30cm2, that is, the clamping force is not less than 450Kgf.
CNC machine tool fixture suitable for large batch processing
High-volume machining cycle = machining waiting time + workpiece machining time + production preparation time "machining waiting time" mainly includes the time at which the workpiece is clamped and replaced. The traditional manual machine tool fixture "work clamping time" can reach 10~30% of the large-scale machining cycle, so that "workpiece clamping" becomes a key factor affecting the production power, and it is also the key object of the machine tool fixture "tapping potential". Therefore, it is advisable to use special fixtures for rapid positioning and rapid clamping (release) for high-volume processing. The following three types of machine tool fixtures can be given priority:
Hydraulic/pneumatic clamp
The hydraulic/pneumatic clamp is a special fixture that uses hydraulic pressure or air pressure as a power source to complete positioning, support and compression of the workpiece through hydraulic components or pneumatic components.
The hydraulic/pneumatic clamp can accurately and accurately determine the mutual orientation between the workpiece and the machine tool and the tool. The azimuth accuracy of the workpiece is guaranteed by the fixture, and the machining precision is high. The positioning and clamping process is agile, which greatly saves the clamping and release of the workpiece. The moment; together with compact structure, multi-station clamping, high-speed heavy cutting, automatic control and other advantages.
The above advantages of the hydraulic/pneumatic clamp make it particularly suitable for use in CNC machine tools, processing bases, and flexible production lines, and are particularly suitable for large-volume processing.
Electric permanent magnet fixture
The electric permanent magnet fixture has the advantages of rapid clamping, easy completion of multi-station clamping, multi-face machining in one clamping, stable and firm clamping, energy saving and environmental protection, and automatic control. Compared with conventional machine tool fixtures, the electric permanent magnet fixture can greatly shorten the clamping time, reduce the number of clamping times, and improve the clamping power, so it is not only suitable for small batch production, but also suitable for mass production.
Glossy clamp base
There are not many applications of glossy fixture bases in China, but they are widely used in industrialized countries such as Europe and the United States. It is actually a finished blank of the finished fixture base, the positioning part of the component and the machine tool positioning part and the positioning surface of the part on the fixture are now finished. Users can process and manufacture special fixtures according to their actual needs.
The smooth jig pedestal can shorten the cycle for producing a dedicated jig and reduce the production preparation time. Therefore, the cycle of mass production can be shortened as a whole, and the production power can be improved. Together, the production cost of the special jig can be reduced. Therefore, the base of the smooth surface fixture is particularly suitable for mass production in a tight cycle.
Rational use of fixtures to explore equipment potential
Experience has shown that in order to improve the processing efficiency of CNC machine tools, it is not enough to just "select the right" CNC machine tool fixtures. It is also necessary to work hard on "using good" CNC machine tool fixtures.
Here are three common ways to do this:
Multi-station method
The basic principle of the multi-station method: After a plurality of workpieces are clamped at one time, the unit shortening unit clamping time is reached, and the intention of cutting the useful cutting moment of the tool is prolonged. A multi-station jig is a jig having a plurality of positioning clamping orientations.
With the development of CNC machine tools and the demand for power production by users, the use of multi-station fixtures is increasing. Multi-station planning is becoming more and more popular in the construction planning of hydraulic/pneumatic clamps, combined fixtures, electric permanent magnet fixtures and fine combination pliers.
Group application
Putting the same fixtures on the same workbench, the same can be done for the "multi-station" setup. The fixtures touched by this method should usually be "standardized planning, high-precision production", otherwise it is difficult to reach the requirements of CNC machine tool processing.
The group application method can make full use of the CNC machine tool stroke, which is beneficial to the balanced wear of the machine tool transmission parts; the related fixtures can be used independently, complete the multi-piece clamping, and can be combined to complete the large standard workpiece clamping.
Partial quick change method
Part of the quick change method is to replace the part of the CNC machine tool fixture (positioning component, clamping component, tool setting component and guiding component) with the rapid replacement of the function or application mode of the agile fixture. For example, the quick-change combination pliers can be used to change the clamping function through the rapid replacement of the jaws, for example, from the clamping material to the clamping bar; and the clamping method can be changed by rapidly replacing the clamping elements. For example, from manual clamping to hydraulic clamping. Partial quick change method has greatly shortened the time of replacing and adjusting the fixture, and the advantage is obvious in small batch production.