Flowtam Light Industry Machinery Co., Ltd. , http://www.flowtamtank.com
Keywords: product design principles and skills
1 Product design principles
Reasonable design should make the manufacturing cost the lowest under the premise of ensuring the necessary functions of the product, which is the subject to be explored in this paper.
(l) Customer's requirements for product features and services must be met. The construction machinery provides customers with not only the functions of the products, but also the after-sales services that support these functions. Therefore, in the design process, it is necessary to aim at different functional features of the product, and to make the product have good maintenance convenience.
(2) Comply with the state's industrial development policies and relevant laws and regulations.
(3) Adhere to the principle of “three-oriented†of standardization, generalization and serialization.
(4) Meet the social requirements for environmental protection.
(5) In line with the laws of technological innovation, attach importance to the protection of intellectual property rights.
(6) From the actual process level and production capacity of the enterprise, emphasize the combination of design, process and production. Product design is not just a pattern design, but also a process design and production design. Production design should be studied mainly from the following aspects:
1 simplify the function or shape of the part;
2 to maximize the standardization, generalization and serialization of products;
3 Make the material grades, varieties and specifications specified in the design drawings as consistent as possible with the existing materials;
4 Considering the blank process and the processing process more effectively;
5 Judging the rationality of the process design according to the processing technology, operation rules and related information used in the current normal production of the enterprise;
6Select the dimensional tolerance and surface roughness that can be guaranteed by the mature processing technology;
7 Comprehensive analysis of the information related to the production process, the necessary value engineering analysis of the main components.
2 Product design skills
2.1 Adopting the principle of “three-in-one†(l) Parts should be replaced with standard parts or standard parts or purchased parts.
(2) When designing splines and threads, it should be easy to use standard tools and measuring tools for processing and testing. In particular, priority should be given to the existing tools and measuring tools.
(3) For the design of large structural parts and steel castings, use fasteners that do not need to be tapped as much as possible, such as replacing the screw holes with welded nut plates. When designing large workpieces, consider using a well-formed hole as a reference to weld the nutplate.
(4) Try to use existing mature parts or mature structures and process methods to make the products serialized and generalized. With this "building block" method, the design speed can be accelerated, the prototype period of new product prototypes can be shortened, and the market can be occupied as early as possible.
(5) Establish the company's own “standard parts library†and speed up the design and trial progress. The author's company has now established and gradually improved the “factory standard parts†system and the “factory standard parts libraryâ€, and selected the same or similar parts used in more than three main products as factory standard parts.
(6) Select a uniform taper, consistent thickness and size of the steel casting material as much as possible.
2.2 Improved design from shape and structure (1) Minimize parts. Combine several parts into one part, for example, change the weldment to a stamped part to reduce the number of parts.
(2) Design the part into a symmetrical structural form.
(3) Designing parts with similar shapes for use in several products to be designed as universal parts.
(4) Simplify the shape of each part, improve the shape of the part, reduce the shape of the bend, and sometimes change the part that is difficult to ensure the dimensional accuracy during the pressing to the welded part.
2.3 Improved process plan (l) Avoid unnecessary cutting, especially the unnecessary cutting of the clamping surface.
When welding parts are prepared by welding with a highly automated welding robot, pre-weld processing of the components should be considered to ensure the mutual positional dimensions between the components of the welded parts. Otherwise, the error will be too large and the robot will not be able to automatically track the welding.
(2) Under the premise of ensuring reliable and reasonable use of components, reduce the machining accuracy level requirements such as dimensional tolerance, surface roughness and shape tolerance.
(3) Reduce the bending shape and complexity of parts, reduce scrap rate and manufacturing costs.
(4) When the steel is subjected to length cutting, the flame cutting should be changed to the steel cutting and cutting; the flame cutting of the general material is changed to shearing with the shearing machine; the rectangular strip workpiece is changed from the four sides to the cutting. With strip steel, it is only the shearing of the length.
2.4 Process technology that saves resources and reduces pollution (1) Cast steel parts are changed to welded parts.
It is difficult for the foundry industry to completely solve the environmental pollution problem and it is easy to produce casting defects, which can be easily solved by welding techniques and welding parts.
(2) Under the premise of ensuring the strength of the parts and optimizing the thickness of the plate, the weight of the parts is minimized. The design of the structural weldment must be such that the rib is stressed and the weld is stressed. The use of thick plates in the construction of structural weldments is often not a requirement for strength, but a need for stiffness, i.e., small deformation of the slab during welding, or small deformation when the weldment is loaded. Some individual slabs can often be replaced by thinner plates with appropriate ribs, which not only reduces the total weight, but also increases the load carrying capacity.
(3) Select reasonable parameters such as weld length and weld angle. A considerable number of designers often confuse “strength welds†with “joint weldsâ€. In design, there is often a tendency for the welds in the weldments to be welded and the weld angles to be better. In fact, the choice of welding penetration or welding is not necessary, the designer should carefully consider the decision. The stress state of the weldment should be carefully studied before deciding the weld angle and weld length to be used. The use of intermittent welds is never required to be fully welded in the full length direction, so that one can save welding processing costs, and the second can also reduce welding deformation; can use fillet welds, try not to open the groove after the parts Re-weld to reduce the process of opening a bevel.
(4) A process with less or no cutting is used to increase the strength of the workpiece and reduce the manufacturing cost. For gear processing, the automotive industry has long used a large number of methods of integral rolling and precision forging to reduce or even eliminate the machining of the tooth profile. The drive axle differential gears of construction machinery are also beginning to use precision forged gears. Precision forging makes the metal fiber envelop in the direction of tooth formation. Unlike the general gear cutting the metal fiber, the precision forging gear greatly improves the bearing strength of the gear, reduces the cutting amount, and even eliminates the need for tooth forming. , reducing manufacturing costs.
(5) Replace some free forging forgings with welded parts as much as possible.
(6) Uniform parts heat treatment technical requirements and process specifications, so that different parts can be simultaneously heat treated in the same furnace to improve the utilization rate of the electric furnace;
(7) Make full use of the residual heat of the forging, continue heating after forging, and directly perform heat treatment such as forging and normalizing.
(8) According to the specific conditions of the parts, develop reasonable heat treatment technical requirements.
Medium carbon steel or alloy medium carbon steel parts are treated with quenching and tempering, which can effectively improve and fully exert the mechanical strength and other properties of the material. However, for the shaft parts with relatively large shaft diameter, the effective layer of quenching during quenching and tempering is only a few millimeters, and there is little left after quenching and tempering, and the state of the heart is not actually improved. Therefore, according to the author's experience, the solid shaft parts above φ70 can be considered to be processed by normalizing ten machining or normalizing ten hardening ten grinding outer circle. Because shaft parts are often quenched by high frequency or medium frequency, heating only occurs on the outer surface of the outer circle, and the core weave is practically impossible to be hardened. If heated in a salt bath furnace, the core can be heated, but the hardenability of the material is limited, and the quenching during quenching and tempering is actually hardened in the core. Normalizing can effectively improve the overall organization of the parts and refine the metallographic structure of the heart, which is enough for some parts.
(9) When designing the hydraulic system, the overall layout of the machine should be fully considered. The volume of the hydraulic oil tank should be sufficient to minimize the amount of hydraulic oil; the pipeline is simple and compact, and the length is as short as possible. In the same way, when designing the electrical system and the brake pipe system, the cable or brake pipe should be made reasonable and the length should be the shortest.
3 Conclusion
Product design is a complex process of comprehensive information processing. The final result is to draw lines, symbols and numbers into reasonable design drawings. Designers should consider the following aspects comprehensively;
(l) Simplify the shape of each part to make the machine structure simple;
(2) Combine the functions of parts and reduce the type or quantity of parts;
(3) Apply new structures, new processes, new materials, and new principles to simplify product structure and improve product reliability;
(4) Decompose the components and study the simplest structure of assembly and assembly;
(5) grouping similar parts;
(6) Serialization analysis of similar products according to the standard number sequence;
(7) Realize the generalization and standardization of product parts.
The key to improving the design quality of product designers is to consciously and actively learn the knowledge related to the production process and processing technology, and master the design skills.
Product design principles and techniques
Abstract: The lowest manufacturing cost is the ultimate goal of product design. This paper introduces the principles and product design techniques that should be followed in the design process of engineering machinery products, and provides excellent and reasonable products for engineers and technicians, and provides means and methods for reference.