In the field of machining, after CNC machining process methods and division of processes, the main content of the process route is to rationally arrange these processing methods and processing sequence. In general, CNC machining of mechanical parts includes cutting, heat treatment and auxiliary processes such as surface treatment, cleaning and inspection. The sequence of these processes directly affects the quality, production efficiency and cost of the parts. Therefore, when designing CNC machining routes, the order of cutting, heat treatment and auxiliary processes should be reasonably arranged, and the connection problem between them should be solved.

In addition to the basic steps mentioned above, factors such as material selection, fixture design and equipment selection need to be considered when developing a CNC machining route. Material selection is directly related to the final performance of parts, different materials have different requirements for cutting parameters; The fixture design will affect the stability and accuracy of the parts in the process of processing; Equipment selection needs to determine the type of machine tool suitable for its production needs according to the characteristics of the product.

1, the processing method of precision machinery parts should be determined according to the characteristics of the surface. On the basis of familiar with the characteristics of various processing methods, mastering the processing economy and surface roughness, the method that can ensure the processing quality, production efficiency and economy is selected.

2, select the appropriate drawing positioning reference, according to the principle of crude and fine reference selection to reasonably determine the positioning reference of each process.

3, When developing the machining process route of the parts, it is necessary to divide the rough, semi-fine and finishing stages of the parts on the basis of the analysis of the parts, and determine the degree of concentration and dispersion of the process, and reasonably arrange the processing sequence of the surfaces. For complex parts, several schemes can be considered first, and the most reasonable processing scheme can be selected after comparison and analysis.

4, determine the processing allowance and process size and tolerance of each process.

5, select machine tools and workers, clips, quantities, cutting tools. The selection of mechanical equipment should not only ensure the quality of processing, but also be economical and reasonable. Under the conditions of mass production, general machine tools and special jigs should generally be used.

6, Determine the technical requirements and inspection methods of each major process.Determining the cutting amount and time quota of each process is usually decided by the operator for a single small batch production plant. It is generally not specified in the machining process card. However, in the medium batch and mass production plants, in order to ensure the rationality of production and the balance of rhythm, it is required that the cutting amount must be specified, and must not be changed at will.

First rough and then fine

The processing accuracy is gradually improved according to the order of rough turning - semi-fine turning - fine turning. The rough lathe can remove most of the machining allowance of the workpiece surface in a short time, thereby increasing the metal removal rate and meeting the requirement of the uniformity of the allowance. If the residual amount left after the rough turning does not meet the finishing requirements, it is necessary to arrange a semi-finishing car for finishing. The fine car needs to ensure that the outline of the part is cut according to the drawing size to ensure the processing accuracy.

Approach first and then far

Under normal circumstances, the parts close to the tool should be processed first, and then the parts far away from the tool to the tool should be processed to shorten the moving distance of the tool and reduce the empty travel time. In the process of turning, it is beneficial to maintain the stiffness of the blank or semi-finished product and improve its cutting conditions.

The principle of internal and external intersection

For parts that have both an inner surface (inner cavity) and an outer surface to be processed, when arranging the processing sequence, the inner and outer surfaces should be roughed first, and then the inner and outer surfaces should be finished. Must not be part of the surface of the part (outer surface or inner surface) after processing, then processing other surfaces (inner surface or outer surface).

Base first principle

Priority should be given to the surface used as the finishing reference. This is because the more accurate the surface of the positioning reference, the smaller the clamping error. For example, when machining shaft parts, the center hole is usually machined first, and then the outer surface and end face are machined with the center hole as the precision basis.

The principle of the first and the second

The main working surface and assembly base surface of the parts should be processed first, so as to find out the modern defects on the main surface in the blank early. The secondary surface can be interspersed, placed on the main machined surface to a certain extent, before the final finishing.

The principle of the face before the hole

The plane outline size of the box and bracket parts is large, and the plane is generally processed first, and then the hole and other sizes are processed. This arrangement of processing sequence, on the one hand with the processed plane positioning, stable and reliable; On the other hand, it is easy to process the hole on the machined plane, and can improve the processing accuracy of the hole, especially when drilling, the axis of the hole is not easy to deviate.

When developing the machining process of parts, it is necessary to select the appropriate processing method, machine tool equipment, clamp measuring tools, blank and technical requirements for workers according to the production type of parts.

Sheet metal, CNC, 3D printing, is the current market for equipment shell, structural parts, the most common three processing methods.

Each has its own advantages and disadvantages, and sheet metal processing is relatively simple because of the characteristics of forming, high efficiency and low cost, and there are advantages in sample, small batch and mass production.

The common raw materials for sheet metal processing are iron, aluminum, stainless steel and other metal plates, and the main processing technology is laser cutting, bending, riveting, stamping, welding, spraying and other major processes.

Sheet metal raw materials are standard plates, mainly divided into the following three categories: iron, aluminum, stainless steel.Under the same area, iron plate is the cheapest, followed by aluminum plate, stainless steel is the most expensive.

Material property

1. Rust

Iron plate must rust, 201 May rust, 304 does not rust, aluminum plate does not rust.

The iron plate is definitely rusty, the general appearance of the parts are through the surface treatment process such as spraying, painting, etc., to solve such problems, but the surface treatment has increased some costs, the price may not be high, but it is particularly important in mass production.

In order to solve this problem, there is also a kind of iron plate called galvanized plate（Galvanized sheet is divided into two kinds of galvanized sheet with flowers and without flowers）, it is on the basis of the original plate, plated with zinc, or almost the same price, but to solve the problem of rust, but the galvanized layer of bumps and scratches will also rust.

In order to reduce costs, galvanized sheets are generally used in the internal structure of the equipment. Of course, it can also be used as an exterior part.

（In terms of material characteristics, stainless steel 201 is relatively much harder than 304, and 304 toughness will be greater）

2. Machinability

The two main processing processes of sheet metal: bending and welding. In terms of materials, the ductility and tensile strength of iron plates and stainless steel are relatively stable, and bending and welding can be done.

Here focuses on the aluminum this material, it has different series, common 5052, 6061, 7075.

7 series aluminum, also called aviation aluminum, the highest strength, high hardness, but the hardness is too high is not suitable for bending, a break.

6 series aluminum, strength, hardness in the medium distance, but also not suitable for bending, there is also a risk of breaking.

5 series aluminum, ductility and tensile strength are also stable, suitable for bending.

The choice of aluminum, in addition to whether it is suitable for bending, the difference is also the common surface treatment oxidation process of aluminum, and the color of different series of aluminum after oxidation will also have a little difference.

In addition, compared with iron and stainless steel, the thermal conductivity of aluminum is high, welding is difficult compared with iron and stainless steel, the general factory does not necessarily have the ability to weld aluminum parts, so the welding cost is high, which is also a large part of the reason for affecting the production cost.

Conclusion

1, iron plate is the cheapest, but easy to rust, generally with spray surface treatment process, do internal structural parts and appearance parts can be. Commonly used iron plate is mainly divided into cold rolled plate and galvanized plate two kinds, the difference is whether there is a galvanized layer, the price is similar.

2, aluminum plate material cost is good, can do anodizing, can bend only 5 series, 6 series, 7 series bending will split (there are other 1 series is not introduced), not easy to rust suitable for internal structural parts, welding costs are higher, do special-shaped parts cost will be higher.

3, stainless steel does not do surface spray treatment, can do wire drawing effect, can do structural parts, shaped parts, the only disadvantage is the high price.

Before explaining the process, let's first think about what problems are mainly solved by these processing processes in several major processing industries such as CNC, sheet metal, stamping, injection molding and now 3D printing?

Aside from the specific processing details from the overall point of view, in fact, they are solving the 3D molding problem of different raw materials.

It means that although it is a different processing process, using different raw materials, the purpose of these processing processes is the same - to make a structural part with length, width and height + other characteristics.

In order to introduce the sheet metal forming process more clearly and intuitively, as well as its efficiency and advantages, we will analyze the core process of sheet metal processing - sheet metal bending from the three angles of forming principle, bending principle and cost accounting.

In actual processing, a palm-sized 3D structural part can be formed in just ten seconds, and for slightly larger workpieces, in addition to taking and placing complex points, the molding time is only tens of seconds. Do not have to open a mold to make such a big thing, tens of seconds to form the processing technology can also have? Fast forming and low cost, which is the main advantage of sheet metal bending!

One more detail, the raw material is soft before bending, but after bending, it becomes strong! This detail is a very important concept in sheet metal structural design, sheet metal can be bent to increase strength!

For example, to make a part with a relatively large area, in order to prevent deformation, we can use this strategy to directly strengthen the thin plate by bending, which can both reduce the weight and reduce the cost of raw materials.

Summary of advantages

1, low cost of raw materials: can use very thin materials to achieve a large volume; The bending process can also be used to increase the strength of the plate to solve the deformation risk. It can also be rapidly formed from the plate to the three-dimensional part by bending (remember that a large volume can be mentioned here, referring to the advantages of the sheet class at this level).

2, the molding speed is fast, the molding cost is low, the molding speed does not depend on the size, does not need to open the mold, suitable for proofing and mass production.

Sheet metal processing principles

The bending principle is that through the extrusion of the upper and lower molds, bending workpieces of different Angle sizes can be folded, and the molds are mainly composed of the lower molds and the upper molds. In addition to a molding mold, the lower mold is generally a V-slot lower mold, and different bending molds are selected according to the thickness of the bending material.

The commonly used bending die is mainly divided into two kinds of straight knife and curved knife, the main difference between the straight knife and curved knife is to consider the bending interference avoidance problem.

In addition to some special shapes, in order to ensure accuracy and improve efficiency, some molding molds will also be prepared in advance, such as shutters (which can be processed by bending machines or by punching machines), and commonly used arc molds.

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No machine can be made without holes. To connect the parts together, a variety of different sizes of screw holes, pin holes or rivet holes are required; In order to fix the transmission parts, various mounting holes are needed; The machine parts themselves also have many kinds of holes (such as oil holes, process holes, weight reduction holes, etc.). The operation of machining holes so that the holes meet the requirements is called hole machining.

The surface of the inner hole is one of the important surfaces of the mechanical parts. In mechanical parts, parts with holes generally account for 50% to 80% of the total number of parts. The types of holes are also diverse, there are cylindrical holes, conical holes, threaded holes and shaped holes. Common cylindrical holes are divided into general holes and deep holes, and deep holes are difficult to process.

1. First of all, the difference between U drill and ordinary drill is that U drill uses the peripheral blade and the center blade, at this Angle, the relationship between U drill and ordinary hard drill is actually similar to the relationship between the machine clamping turning tool and the welding turning tool, and the blade can be replaced directly after the tool is worn without regrinding. After all, the use of indexable blades still saves material than the whole hard drill, and the consistency of the blade makes it easier to control the size of the part.

2. The rigidity of U drill is better, you can use a high feed rate, and the processing diameter of U drill is much larger than that of ordinary drill, the maximum can reach D50~60mm, of course, U drill can not be too small due to the characteristics of the blade.

3.U drill encounter a variety of materials only need to replace the same type of different grades of blade, hard drill is not so convenient.

4. Compared with hard drilling, the precision of the hole drilled by U drilling is still higher, and the finish is better, especially when the cooling and lubrication are not smooth, it is more obvious, and U drilling can correct the position accuracy of the hole, and hard drilling can not be done, and U drilling can be used as a bore knife.

1. U drill can punch holes on surfaces with inclination angles less than 30~ without reducing cutting parameters.

2. After the cutting parameters of U drilling are reduced by 30%, intermittent cutting can be achieved, such as processing intersecting holes, intersecting holes, and phase perforation.

3. U drilling can realize the drilling of multi-step holes, and can boring, chamfer, eccentric drilling.

4. When drilling, the drilling chips are mostly short chips, and the internal cooling system can be used for safe chip removal, without cleaning the chips on the tool, which is conducive to the continuity of the processing of the product, shorten the processing time and improve efficiency.

5. Under the condition of standard length-diameter ratio, no chip removal is required when drilling with U drill.

6. U drill for indexable tool, blade wear without sharpening, more convenient replacement, and low cost.

7. The surface roughness value of the hole processed by U drilling is small, and the tolerance range is small, which can replace the work of some boring tools.

8. The use of U drilling does not need to pre-punch the center hole, and the blind hole bottom surface processed is relatively straight, eliminating the flat-bottom drill.

9. The use of U drilling technology can not only reduce drilling tools, and because U drilling is the head of the cemented carbide blade, its cutting life is more than ten times the ordinary drill, at the same time, there are four cutting edges on the blade, blade wear can be replaced at any time cutting, the new cutting saves a lot of grinding and replacing the tool time, can improve the average efficiency 6-7 times.

1. When using U drill, the rigidity of the machine tool and the neutrality of the tool and the workpiece are high, so U drill is suitable for use on high-power, high-rigidity and high-speed CNC machine tools.

2. When using U drilling, the center blade should be used with good toughness, and the peripheral blade should be used with relatively sharp blades.

3. When processing different materials, should choose different groove blade, under normal circumstances, small feed, small tolerance, U drilling length to diameter ratio, choose the groove blade with smaller cutting force, on the contrary, rough machining, large tolerance, U drilling length to diameter ratio is small, then choose the groove blade with larger cutting force.

4. When using U drilling, we must consider the power of the machine tool spindle, the stability of U drilling clamping, the pressure and flow of cutting fluid, and control the chip removal effect of U drilling, otherwise it will greatly affect the surface roughness and dimensional accuracy of the hole.

5. When installing the U drill, it is necessary to make the U drill center coincide with the center of the workpiece and be perpendicular to the surface of the workpiece.

6. When using U drilling, the appropriate cutting parameters should be selected according to different parts materials.

7. When drilling test cutting, be sure not to reduce the feed or speed at will because of caution and fear, so that the U drill blade is damaged or the U drill is damaged.

8. When using U-drill processing, when the blade is worn or damaged, it is necessary to carefully analyze the reasons and replace the blade with better toughness or more wear-resistant.

9. When using U drill to process step holes, it is necessary to start processing from large holes and then process small holes.

10. When drilling, pay attention to the cutting fluid to have enough pressure in order to flush out the chips.

11. The blade used on the center and edge of the U drill is different, must not be misused, otherwise it will damage the U drill rod.

12. When drilling with U-drill, workpiece rotation, tool rotation, and simultaneous rotation of the tool and workpiece can be used, but when the tool is moved in a linear feed mode, the most common method is to use the workpiece rotation mode.

13. The performance of the lathe should be considered when machining on the CNC car, and the cutting parameters should be adjusted appropriately, generally reducing the speed and low feed.

1. The blade is damaged too fast, easy to break, and the processing cost increases.

2. A harsh whistle is emitted during processing, and the cutting state is abnormal.

3. Machine jitter, affecting the machining accuracy of machine tools.

1. The installation of U drill should pay attention to the positive and negative directions, which blade is up, which blade is down, which is facing inside and which is facing outside.

2. The center height of U drilling must be corrected, according to its diameter size to require the control range, generally controlled within 0.1mm, the smaller the diameter of U drilling, the higher the center height requirements, the center height is not good U drilling two sides will wear, the aperture will be larger, the blade service life will be shortened, small U drilling is easy to break.

3. U drill has very high requirements for coolant, it must be ensured that the coolant is emitted from the center of U drill, the greater the pressure of the coolant, the better, the excess water outlet of the tower can be blocked up to ensure its pressure.

4, U drilling cutting parameters in strict accordance with the manufacturer's instructions, but also to consider different brands of blades, machine power, processing can refer to the load value of the machine tool size, make appropriate adjustments, generally using high speed, low feed.

5.U drill blade to check often, timely replacement, different blades can not be installed reverse.

6. According to the hardness of the workpiece and the length of the tool suspension to adjust the feed amount, the harder the workpiece, the larger the tool suspension, the smaller the cutting amount.

7. Do not use excessive wear of the blade, should be recorded in the production of blade wear and the relationship between the number of workpieces can be machined, timely replacement of new blades.

8. Use sufficient internal coolant with correct pressure. The main function of the coolant is chip removal and cooling.

9.U drill can not be used for processing softer materials, such as copper, soft aluminum, etc.

Honscn has more than ten years of cnc machining experience, specializing in cnc machining, hardware mechanical parts processing, automation equipment parts processing. Robot parts processing, UAV parts processing, bicycle parts processing, medical parts processing, etc. It is one of the high-quality suppliers of cnc machining. At present, the company has more than 50 sets of cnc machining centers, grinding machines, milling machines, high-quality high-precision testing equipment, to provide customers with precision and high-quality cnc spare parts processing services.