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Author: MULAN -Plastic Molding Manufacturer
1. Technological measures to improve machining productivity (1) Shorten the working hours of a single piece First, the technological measures to shorten the basic time. In mass production, since the basic time accounts for a large proportion of the unit time, productivity can be improved by shortening the basic time. The main ways to shorten the basic time are as follows: 1. Increase the amount of cutting, increase the cutting speed, feed rate and back cutting amount, all of which can shorten the basic time. This is an effective method widely used in machining to improve productivity .
However, the improvement of the cutting amount is restricted by the durability of the tool, the power of the machine tool, and the rigidity of the process system. With the emergence of new tool materials, the cutting speed has been rapidly increased. At present, the cutting speed of cemented carbide turning tools can reach 200m/min, and the cutting speed of ceramic tools can reach 500m/min. The cutting speed of polycrystalline synthetic diamond and polycrystalline cubic boron nitride tools that have appeared in recent years to cut ordinary steel can reach 900m/min.
In terms of grinding, the development trend in recent years is high-speed grinding and powerful grinding. 2. Use multiple cutters to cut at the same time. 3. Multi-piece processing This method is to improve productivity by reducing the cutting-in and cutting-out time of the tool or overlapping the basic time, thereby shortening the basic time of each part processing.
There are three ways of multi-piece processing: sequential multi-piece processing, parallel multi-piece processing, and parallel sequential multi-piece processing. 4. Reduce machining allowance. Advanced technologies such as precision casting, pressure casting, and precision forging are used to improve the manufacturing accuracy of blanks and reduce machining allowances to shorten the basic time. Sometimes, machining is not even required, which can greatly improve production efficiency.
Second, shorten the auxiliary time. Auxiliary time also occupies a large proportion in the single piece time, especially after the cutting amount is greatly increased, the basic time is significantly reduced, and the proportion of auxiliary time is even higher. At this time, taking measures to reduce auxiliary time becomes an important direction to improve productivity.
There are two different ways to shorten the auxiliary time, one is to realize the mechanization and automation of auxiliary actions, thereby directly reducing the auxiliary time; the other is to make the auxiliary time coincide with the basic time, and indirectly shorten the auxiliary time. 1. Directly reduce the auxiliary time. The workpiece is clamped with a special fixture, and the workpiece does not need to be aligned during clamping, which can shorten the time for loading and unloading the workpiece.
In mass production, high-efficiency pneumatic and hydraulic fixtures are widely used to shorten the time for loading and unloading workpieces. In single-piece small batch production, due to the limitation of the manufacturing cost of special fixtures, in order to shorten the time for loading and unloading workpieces, combined fixtures and adjustable fixtures can be used. In addition, in order to reduce the auxiliary time of shutdown measurement during processing, active detection devices or digital display devices can be used for real-time measurement during processing to reduce the measurement time required during processing.
The active detection device can measure the actual size of the machined surface during processing, and automatically adjust the machine tool and control the work cycle according to the measurement results, such as the automatic measurement device for grinding. The digital display device can continuously and accurately display the movement amount or angular displacement of the machine tool during the machining process or machine tool adjustment process, which greatly saves the auxiliary time of stopping the measurement. 2. Indirectly shorten the auxiliary time.
In order to fully or partially overlap the auxiliary time and the basic time, the method of multi-station fixture and continuous processing can be used. 3. Shorten the time for setting up work. Most of the time for arranging work is spent on changing tools, so the number of tool changes must be reduced and the time required for each tool change must be reduced. Improving the durability of the tool can reduce the number of tool changes.
The reduction of tool change time is mainly realized by improving the installation method of the tool and adopting the tool fixture. For example, various quick-change tool holders, tool fine-tuning mechanisms, special tool-setting samples or sample pieces, and automatic tool-changing devices are used to reduce the time required for tool loading and unloading and tool setting. For example, the use of indexable carbide insert tools on lathes and milling machines not only reduces the number of tool changes, but also reduces the time for tool loading and unloading, tool setting and sharpening.
4. Technological measures to shorten the preparation and termination time. There are two ways to shorten the preparation and finalization time: first, expand the production batch of products to relatively reduce the preparation and finalization time allocated to each part; second, directly reduce the preparation and finalization time. The expansion of product production batches can be realized through the standardization and generalization of parts, and the production can be organized by group technology.
(2) Carrying out supervision of multiple machine tools The supervision of multiple machine tools is an advanced labor organization measure. It is obvious that a worker can manage several machine tools at the same time to improve productivity, but two necessary conditions should be met: First, if one person is in charge of M machine tools, the sum of the operating time of workers on any M-1 machine tools should be less than another Second, each machine tool must have an automatic parking device. (3) Adopting advanced techniques 1. Blank preparation.
Using new technologies such as cold extrusion, hot extrusion, powder metallurgy, precision forging, and explosive forming can greatly improve the precision of the blank, reduce the workload of machining, save raw materials, and significantly increase productivity. 2. Special processing. For extra-hard, extra-tough, extra-brittle and other difficult-to-process materials or complex profiles, the use of special processing methods can greatly improve productivity.
If the general forging die is processed by electrolysis, the processing time can be reduced from 40 to 50 hours to 1 to 2 hours. 3. Use less and no cutting processing. Such as cold extrusion gear, rolling screw, etc.
4. Improve processing methods, reduce manual and low-efficiency processing methods. For example, in mass production, broaching and rolling are used instead of milling, reaming and grinding, and fine planing, fine grinding and diamond boring are used instead of scraping and grinding. (4) Using automated manufacturing system The automated manufacturing system is an organic whole composed of a certain range of processed objects, various equipment with a certain degree of flexibility and automation, and high-quality people. It accepts external information, energy, funds, and accessories. And raw materials, etc., under the joint action of humans and computer control systems, a certain degree of flexible and automated manufacturing is realized, and finally products, documents, waste materials, and environmental pollution are output.
The use of automated manufacturing systems can effectively improve labor conditions, significantly increase labor productivity, greatly improve product quality, effectively shorten production cycles, and significantly reduce manufacturing costs. 2. Design measures to improve machining productivity When designing, under the premise of ensuring the performance of product parts, the parts structure should have a good processing technology, and materials with good processing technology should be selected to reduce processing difficulties and improve labor productivity. So as to obtain good economic benefits. (1) Improve the structural manufacturability of parts In order to make mechanical products have good structural manufacturability, the following measures are often adopted in the design: 1. Improve the degree of "three modernizations" of parts and components (standardization of parts, generalization of parts, product series As far as possible, use the mastered technology and standardized and serialized parts and components, and try to borrow the same type of parts that have been produced by our factory, so that the designed structure has a good inheritance.
2. Use parts with simple surface geometry and arrange them on the same plane or on the same axis as possible to facilitate processing and measurement. 3. Reasonably determine the manufacturing accuracy of parts and the assembly accuracy of products. On the premise of ensuring the performance of the product, the manufacturing precision and assembly precision should be reduced as much as possible.
4. Increase the proportion of parts made by non-cutting methods and parts made by lower-cost cutting methods. Obviously, the larger the proportion of these two parts in the product, the better the craftsmanship of the product. (2) Select the workpiece material with good machinability The machinability of the workpiece material directly affects the cutting efficiency, power consumption and surface quality of the part.
When designing products, under the premise of ensuring the performance of the product, the workpiece material with good cutting performance should be selected as much as possible and the heat treatment measures that can improve the cutting performance of the material should be adopted to improve productivity and reduce cutting processing costs. The machinability of a material mainly depends on the physical and mechanical properties of the material. Generally speaking, materials with high strength and hardness, good plasticity and toughness, and poor thermal conductivity have poor cutting performance, and vice versa.
In actual production, heat treatment is often used to change the metallographic structure and mechanical properties of materials to improve the machinability of workpiece materials. For cast iron with high hardness, high-temperature spheroidizing annealing is generally used to spheroidize the flake graphite to reduce the hardness and improve the machinability of the material. Summary: Improving the production efficiency of machining is not only an update of the process concept, but also an improvement of the management concept.
Adopt advanced cutting tools and machine tools to achieve high-speed and efficient cutting, and at the same time use related technologies and management methods to optimize the entire processing technology, and use various methods to improve processing efficiency and achieve high-speed cutting. Efficient cutting, efficient processing. The ultimate goal.