Mini Light String,Mini String Lights,Mini Led Christmas Lights,Led Mini String Lights DONGGUAN JIANXING LIGHTING ELECTRIC APPLIANCES CO., LTD , https://www.szrslightstring.com
First, the choice of tools
1. Types of commonly used tools for CNC milling
There are many types of CNC milling tools. In order to adapt to the high speed, high efficiency and high degree of automation of CNC machine tools, the tools are developing in the direction of standardization, generalization and modularization, mainly including milling tools and hole machining tools. In order to meet the requirements of efficient and special milling, special tools for special applications have been developed. There are many methods for classifying CNC milling tools. According to the tool structure, it can be divided into: 1 integral type; 2 inlaid type, using welding or machine clamp type connection, and the machine clamp type can be divided into two types: non-indexing and indexable. 3 special types, such as composite tools, shock-absorbing tools, etc. According to the materials used in the manufacture of tools can be divided into: 1 high-speed steel tools; 2 carbide tools; 3 diamond tools; 4 other material tools, such as cubic boron nitride tools, ceramic tools. From the cutting process can be divided into: flat end mill, round end mill, ball head knife and taper milling cutter.
2, CNC milling processing requirements for the tool
In order to ensure the machining accuracy of CNC milling machine tools, improve the production efficiency of CNC milling machine tools and reduce the consumption of tool materials, when selecting CNC milling machine tool and tool materials, in addition to meeting the basic conditions that ordinary machine tools should have, it is also necessary to consider Many factors such as the working conditions of the tool in the milling machine, such as the chip breaking performance of the chip and the rapid adjustment and replacement of the tool, therefore put forward higher requirements for the tool and tool material.
1) The rigidity of the milling cutter is better. One is to use the large cutting amount to improve the production efficiency; the other is to adapt to the difficulty of adjusting the cutting amount during the processing of the CNC milling machine. When the machining allowances of the workpieces are very different, the general milling machine can easily solve the situation by using the layered milling method, and the CNC milling must advance according to the specified path of the program. Like “uniform strain†like a universal milling machine, unless it can be pre-conceived during programming, the milling cutter must return to the origin and start from the beginning by changing the cutting surface height or increasing the tool radius compensation value. However, this will inevitably lead to the emptying of the place where the margin is small, which reduces the production efficiency. If the rigidity of the tool is good, it is not necessary to do so. 2) The durability of the milling cutter is high, especially when a milling cutter has a lot of processing contents, such as the tool is not durable and wears faster, it will affect the surface quality and machining accuracy of the workpiece, and will increase the adjustment caused by the tool change. The number of knives and tooling will also leave the working surface with a knife step formed by the tooling error, which reduces the surface quality of the workpiece. In addition to the above two points, the interchangeability is good, and it is convenient to change the knife quickly; the size of the tool is easy to adjust to reduce the adjustment time of the tool change; the tool should be able to reliably break the chip or the chip to facilitate the elimination of the chip; serialization, Standardization to facilitate programming and tool management, etc. These are the different requirements for CNC machining and general machining.
3, the choice of CNC milling tool type
The selection of the tool is carried out in the human-computer interaction state of the NC programming. The tool and tool holder should be selected correctly according to the machining capacity of the machine tool, the performance of the workpiece material, the machining process, the amount of cutting and other relevant factors. The general principle of tool selection is: easy installation and adjustment, good rigidity, durability and high precision. Under the premise of meeting the processing requirements, try to choose a shorter tool holder to improve the rigidity of the tool processing. In production, the geometry of the part being machined is the primary basis for selecting the type of tool. 1) Selection of milling tools: When machining curved parts, in order to ensure that the cutting edge of the tool and the machining contour are tangent at the cutting point, and avoid the interference between the cutting edge and the contour of the workpiece, a ball-end knife is generally used, and a two-edge milling cutter is used for rough machining. Four-blade milling cutters for semi-finishing and finishing; in milling larger planes, in order to improve production efficiency and improve surface roughness, insert-type disc milling cutters are generally used; general milling is generally used for milling facets or step faces Knife; When milling the keyway, in order to ensure the dimensional accuracy of the groove, generally use two-blade keyway milling cutter; 2) Selection of hole machining tool: CNC machine tool hole machining generally has no die, due to the rigidity of the drill bit and poor cutting conditions, the drill diameter is selected. D should meet the condition of L/D≤5 (L is the drilling depth); use the center drill to locate the hole before drilling to ensure the positioning accuracy of the hole processing; before the fine twisting, the floating reamer can be used, and the hole before the reaming should be poured Angle; when boring, try to use a symmetrical multi-blade boring head for cutting to balance the boring vibration; try to choose a thicker and shorter shank to reduce the cutting vibration. In the economical NC machining, since the sharpening, measuring and replacing of the tool are mostly manual and manual, the occupation time is long. Therefore, the order of the tools must be arranged reasonably. Generally, the following principles should be followed: 1 Minimize the number of tools; 2 After a tool is clamped, all the machining parts that can be carried out should be completed; 3 The rough-finished tools should be used separately, even for tools of the same size; 4 First milling and drilling; 5 first surface finishing, then 2D contour finishing; 6 When possible, the automatic tool change function of CNC machine tools should be used as much as possible to improve production efficiency. In addition, the durability and accuracy of the tool are highly dependent on the tool price. It must be noted that in most cases, the choice of a good tool increases the tool cost, but the resulting processing quality and processing efficiency increase. , can make the entire processing cost greatly reduced. In short, according to the heat treatment state, cutting performance and machining allowance of the workpiece material to be processed, selecting a milling cutter with good rigidity and high durability is a prerequisite for fully utilizing the production efficiency of the CNC milling machine and obtaining satisfactory processing quality.
Second, the determination of cutting amount
During NC programming, the programmer must determine the amount of cut for each process and write it in the program as an instruction. The amount of cutting includes the cutting speed, the amount of back-feeding or the amount of side-feeding and the feed rate. For different processing methods, different cutting amounts are required. The selection principle of cutting amount is to ensure the machining accuracy and surface roughness of the parts, to maximize the cutting performance of the tool, to ensure reasonable tool durability and to fully utilize the performance of the machine to maximize productivity and reduce costs.
(1) Determination of cutting speed The cutting speed of milling is inversely proportional to the durability of the tool T, the feed amount per tooth fz, the amount of back-feeding knife ap, the amount of side-feeding knife ae, and the number of milling cutter teeth Z, and the diameter of the milling cutter d Just proportional. The reason is that when fz, ap, ae, and Z increase, the number of simultaneous working teeth increases, the blade load and the cutting heat increase, and the tool wear is accelerated, so the tool durability limits the cutting speed. If the diameter of the milling cutter is increased, the heat dissipation condition can be improved and the cutting speed can be increased accordingly. The table below lists the reference values ​​for the milling cutting speed.
Cutting speed reference table during milling
Workpiece material hardness (HBS) cutting speed Vc (m / min)
High speed steel milling cutter carbide milling cutter
Steel <22518~4266~150
225~32512~3654~120
325~4256~2136~75
Cast iron <19021~3666~150
190~2609~1845~90
260~3204.5~1021~30
(2) Determination of feed rate Feed speed F is an important parameter in the cutting amount of CNC machine tools. It is mainly selected according to the machining accuracy and surface roughness requirements of the parts and the material properties of the tools and workpieces. The maximum feed rate is limited by the machine stiffness and the performance of the feed system. In contour machining, the feed rate should be appropriately reduced near the corner to overcome the "overtravel" or "underrun" phenomenon at the corner of the contour due to inertia or process system deformation. The principle of determining the feed rate: 1) When the quality requirements of the workpiece can be guaranteed, in order to improve the production efficiency, a higher feed rate can be selected. Generally, it is selected in the range of 100~200mm/min. 2) When cutting or machining deep holes or machining with high speed steel tools, it is advisable to select a lower feed rate, generally in the range of 20~50mm/min. 3) When the machining accuracy and surface roughness are high, the feed rate should be selected to be smaller, generally in the range of 20~50mm/min. 4) When the tool is in the free travel, especially when the distance is “return to zeroâ€, the highest feed speed given by the CNC system can be selected.
(3) Determination of the amount of back-feeding knife (or side-cutting knife) Under the premise of ensuring the processing quality of the machined surface quality, the amount of back-feeding knife (ap) should be determined according to the rigidity of the machine tool, workpiece and tool, and the rigidity is allowed. Under the condition, the amount of backing knife should be equal to the machining allowance of the workpiece as much as possible, which can reduce the number of passes and improve production efficiency. The surface roughness of the workpiece is required to be Ra3.2~12.5μm. It is divided into rough milling and semi-finishing milling. The rough milling has a semi-finishing allowance of 0.5~1.0mm. The surface roughness of the workpiece is Ra0.8~3.2. Mm, can be divided into rough milling, semi-finishing milling, fine milling three-step milling, semi-finishing milling end milling cutter or circumferential milling side cutting knife taking 1.5~2mm, finishing milling end milling cutter 0.5~1mm, the circumference of the milling side is 0.3~0.5mm.
In short, CNC programming of parts has great flexibility. Only by correctly understanding the above process parameters and summarizing them in practice, can we produce high-quality machining programs and produce high-quality mold parts.
Christmas Mini Light String is waterproof and durable.
Can be used in any season and many applications such as wedding, party,
garden etc. We have different wire model and Replacement Bulb type to
choose.
Decorative string
lights are not just for holidays anymore . Instantly transform indoor
and outdoor spaces with a wide selection of covers and finishes that match current trends and personal tastes and expressions.
Celebrate any season ,event or inspired whim with a charming new set of outdoor string lights!
Discussion on the problem of determining tool selection and cutting amount
As we all know, in the process of numerical control programming with CAM software, the selection of the tool and the determination of the cutting amount are very important. It not only has a great impact on the quality of the machined parts, but also can determine the function of the machine tool and the smooth production of safety. . Therefore, whether it is manual programming or computer-aided programming, selecting a reasonable tool and cutting amount during the programming process is a prerequisite for the preparation of high-quality machining programs. In this paper, the problem of tool selection and cutting amount determination that must be faced in NC programming is discussed. Several principles and suggestions are given, and the problems that should be paid attention to are discussed.