01 General Rules of Tool Path
1) Open thick
Under the maximum load of the machine tool, in most cases, the largest possible tool should be selected, the largest possible feed amount, and the fastest possible feed. In the case of the same knife, the feed is inversely proportional to the amount of feed. Under normal circumstances, the load of the machine tool is not a problem. The principle of tool selection is mainly based on whether the two-dimensional angle and three-dimensional arc of the product are too small. After the knife is selected, the knife length is fixed. The principle is that the knife length is greater than the machining depth. For large workpieces, it is necessary to consider whether the chuck interferes.
2) Light knife
The purpose of the light knife is to achieve the processing requirements of the surface roughness of the workpiece and reserve an appropriate margin. Similarly, the light knife should be as large as possible, and the time as fast as possible, because the fine knife needs a longer time, use the most suitable feed and feed. Under the same feed, the larger the transverse feed, the faster, the curved surface feed is related to the surface roughness after processing, the size of the feed is related to the surface shape of the curved surface, and the minimum margin is left as long as the surface is not damaged. Quantity, use the largest knife, the fastest speed, and the appropriate feed.
All clamps are horizontal and vertical.
1) Vise clamping
The clamping height should not be less than 10mm, and the clamping height and processing height must be specified when processing the workpiece. The processing height should be about 5mm higher than the vise plane, the purpose is to ensure the firmness, and at the same time not to damage the vise. This kind of clamping is a general clamping, and the clamping height is also related to the size of the workpiece. The larger the workpiece, the higher the clamping height.
2) Clamping of splint
The clamping plate is coded on the worktable, and the workpiece is locked on the clamping plate with screws. This clamping is suitable for workpieces with insufficient clamping height and large processing force, generally medium and large workpieces, and the effect is better.
3) Clamping of code iron
When the workpiece is large, the clamping height is not enough, and the wire is not allowed to be locked at the bottom, the clamping iron is used. This kind of clamping needs to be clamped twice. The four corners are first coded, the other parts are processed, and then the four sides are coded to process the four corners. During the second clamping, do not let the workpiece loose, yard first and then loosen. You can also code both sides first and process the other two sides.
4) Clamping of the tool
For diameters above 10mm, the clamping length shall not be less than 30mm; for diameters below 10mm, the clamping length shall not be less than 20mm. The clamping of the tool must be firm to prevent collision with the tool and direct insertion of the workpiece.
03 Classification of tools and their application
(1) Classified by material
1) White steel knife: easy to wear, used for thickening of copper and small steel materials.
2) Tungsten steel knife: used for corner cleaning (especially steel) and light knife.
3) Alloy knife: similar to tungsten steel knife.
4) Purple knife; used for high-speed cutting, not easy to wear.
(2) According to the cutter head
1) Flat-bottomed knife: used for flat and straight sides, clearing flat corners.
2) Ball knives: used for various curved surface light and light knives.
3) Bull-nose knife (single-sided, double-sided and five-sided): used for roughing steel materials (R0.8, R0.3, R0.5, R0.4).
4) Coarse leather knife: used for roughing, pay attention to the remaining method (0.3) of the margin.
(3) According to the tool bar
1) Straight shank knife: Straight shank knife is suitable for various occasions.
2) Inclined bar knife: But it is not suitable for straight face and the surface with slope less than the slope of the bar.
(4) According to the knife edge
Two-edged, three-edged, four-edged, the more the number of blades, the better the effect, but the more work done, the speed and feed will be adjusted accordingly, and the more blades will have a longer life.
(5) The difference between ball knives and flying knives
1) Ball knife: When the concave ruler is smaller than the ball ruler, and the flat ruler is smaller than the ball R, there is no light (not clear to the bottom corner).
2) Flying knife: The advantage is that it can clear the bottom corner. Comparison of the same parameters: V=R*ω, the speed is much faster (flying knife), and things that are powerful and bright are bright. The disadvantage is that the size of the concave surface and the flat ruler are smaller than the diameter of the flying knife.
04The practice of CNC milling copper male
(1) Under what circumstances need to be a copper public
1) Do not lower the knife to make a copper male. There are still some copper males that cannot be lowered. The shape is protruding and needs to be divided.
2) The knife can go down, but the easy-to-break knife also needs to be made of copper, which depends on the actual situation.
3) Products that require fire patterns need to be made of copper.
4) If the copper can't be made, the bone position is too thin and too high, it is easy to damage and deform, and it is deformed during processing and sparking. At this time, inserts are required.
5) The surface of the east and west (especially the curved surface will be very smooth and uniform) processed by Tong Gong can overcome many problems in fine gongs and many problems in drawing.
6) Thick copper males must be made when precise shapes or large margins are required.
(2) Tonggong’s approach
1) Select the surface to be made of copper, fill in the surface to be complemented, or extend the extended surface to ensure that all edges of the copper are larger than the edges to be beaten and do not damage the surface of other products, and remove unnecessary cleaning. The plane angle that is less than (the intersection with the plane angle is a deeper glue position), fill in a regular shape;
2) Find out the largest shape of Tong Gong and add WeChat: steven52014 will send a copy of the macro program tutorial with a boundary and then project it onto the supporting surface; determine the size of the reference frame, cut off the supporting surface, and the copper diagram is basically completed;
3) Material preparation: length * width * height, length and width ≥ Ymax and Xmax as the reference frame, the length and width of the actual copper material must be greater than the reference frame on the drawing. Height ≥ theoretical size of Tonggong + base frame height + clamping height.
05 The problem of drawing fixed number
1) In the absence of a ready-made processing surface, the plane is divided into four sides, the center is to the origin, the top surface is zero, and when the top surface is not flat (for copper), a margin of 0.1 is left, that is, when the number is touched, the actual value is 0 (z ), which is 0.1 lower on the graph.
2) When there is a ready-made machined surface, make the ready-made face on the drawing 0(z), and the plane can be divided into the middle, otherwise the actual height and width of the machined surface should be checked by the number of ready-made edges (single side). , The length is different from the drawing, and it is programmed according to the actual material. Under normal circumstances, first process to the size on the drawing and then process the shape on the drawing.
3) When multiple positions are required for processing, the first position (standard position) must be the benchmark gongs of the other positions, and the length, width and height must be gongs. All the next processing benchmarks must be processed last time. The surface shall prevail.
4) Positioning of the insert: Put it in the whole, padded the bottom to a certain height, and then the drawing also raises this height. The plane is divided into the center according to the whole, and the height is locked with screws at the bottom of the figure; if it is square, it can be straight. Centering; a rougher point can be used for the centering of the largest shape; cut a fixture, center the fixture according to the fixture, determine the relative position of the insert drawing and the fixture, and then place the origin of the drawing at the center of the fixture.
06 rough tool path selection
(1) Surface grooving
1) The key is the choice of scope and the choice of surface. The area of tool path processing is: the selected surface in the selected range is the end surface, and all the places where the tool can go from the highest point to the lowest point are the principle. The selected surface is best to be the entire surface, and the boundary can only be the area to be processed. The area where there is no surface extends less than half of the tool diameter. Because the other surfaces have enough margin, they are automatically protected; it is best to extend the lowest line, because There is an R gong at the lowest point.
2) Knife selection: If the tool cannot be fed in a spiral or oblique line, or the area that cannot be machined, the area where the tool cannot be fed is sealed and left for the second roughing.
3) Before the light knife, be sure to make all the uncut areas thick, especially the small corners, including two-dimensional corners, three-dimensional corners and sealed areas, otherwise the knife will be broken. Secondary roughing: generally use three-dimensional grooving to select the range, flat-bottomed knife, and use for flat grooving and contour toolpaths. Under the condition of not hurting other surfaces, the tool center to the selected boundary is generally not refined. The rapid two-way angle depends on the situation. The spiral feed, the angle is 1.5 degrees, and the height is 1. When the groove shape is strip, it cannot Spiral cutting is used to feed in a diagonal line. Generally, the filter is opened, especially when the curved surface is thick.
4) Retraction: Generally, relative retraction is not required, but absolute retraction is used. When there is no island, relative retraction is used.
(2) Plane trenching
Milling various planes, concave flat grooves, when milling a part of an open plane, you need to define the boundary, in principle, it can feed (more than one tool diameter), and the outside of the opening is larger than half of the tool diameter, and the periphery is closed.
(3) Appearance
When the selected plane is suitable for the shape layering, use the shape layered knife lift (planar shape). When the knife lift point and the knife point are at one point, the knife does not need to be lifted. The z plane generally lifts the knife, try not to use the relative height; the compensation direction is general Right compensation (shun knife).
(4) Tool path setting for mechanical compensation
The correction number is 21, the computer correction is changed to the mechanical correction, the feed is vertical, and the place where the tool cannot pass is changed to a larger R without leaving a margin.
(5) Contour shape
It is suitable for the closed face. If the open face has four circles, the top face should be sealed. If it is within four circles or not four circles, the range and height should be selected (a certain arc is used for thickening). Circumstances: The machining distance in any plane is less than one tool diameter, if it is greater than one tool diameter, a larger tool or two contours of equal height should be used.
(6) Surface streamline
With the best uniformity and crispness, it is suitable for the light knife and can replace the contour shape in many cases.
(7) Radiation knife path
Suitable for situations with large holes in the middle (less use). Matters needing attention: Bouncing the knife, the knife is not sharp, the knife is too long, and the workpiece is too deep to walk around and not go up and down; the sharp corners of the workpiece should be divided into two tool paths, not over, the edge is best when the knife is light. Extend (use the arc to advance and retreat the tool).
07 Clear Angle
1) The clear corner here is a two-dimensional blind corner, which is a part that has not been reached in the previous process. If the light knife needs to go to the place, the corner should be cleared first, and the corner should be cleared by several knives. , Don’t use a knife to clean too many places.
2) Clear three-dimensional corners: open some small grooves and some three-dimensional corners.
3) For easy-breaking knives, we must consider the conditions such as thin knives, too long, and too large processing volume (mainly in the z-direction, depth direction).
4) Tool path: Use two-dimensional shape to walk, only small angle (R0.8) and two-dimensional plane angle can be cleared; use parallel tool path; use contour shape; there is a kind of curved surface and shape that cannot be reached by a knife. The blind corners must be sealed first, and then the corners should be cleared. Small gaps in the large surface are generally sealed first.
08 Zhongguang
1) Zhongguang: as a curved surface steel material and fine male talent Zhongguang.
2) Principle: There is more margin between the layers when the knife is roughed, which is a process to get a better effect when the light knife is used.
3) Features: fast removal, large knife and flying knife, large feed, large spacing; no need to worry about surface quality; flat workpieces do not need to be medium-gloss; contoured workpieces do not need to be medium-gloss, and the contour can be thinner when the contour is thick Putting the two processes together, the finer point refers to the surface margin and the distance between the layers; whether the light is needed, and another important factor is the working material. The harder the material, the light is considered; the processing of the light The direction and the roughing of the light knife are best relative to the things processed in this way, which will have a good effect and uniformity.
09 Light Knife
The light knife is to meet the assembly requirements of various products and molds, so be very careful, and give different tool path settings and parameter settings according to different requirements.
(1) The cutting height and final height of the light knife are changed to 0, and the tolerance design is within 1 wire, without filtering (the smaller the workpiece, the smaller the tolerance, and the tolerance affects the appearance).
(2) The front mold and the parting surface should achieve the best finish, the back mold can be inferior, and other non-matching and void spaces can be rough.
(3) Tool path design is determined by the following factors:
1) Specific shape (such as plane and other surfaces), steep surface and flat curved surface.
2) Whether there are sharp corners between the two sides (the sharp corners are separated).
3) Whether the requirements of the two parts are different (whether to leave a margin, how much margin, and the requirements for finish are different).
4) The problem of the protection surface in the light knife is a big problem. The processed surface must be protected against errors in the processing and protected according to the requirements of the protection surface. Range protection, zero protection regardless of error, height range and plane range; protection surface protection.
5) The extension of the tool path. In the light knife, it is better to make the arc advance and retreat when the tool path is processed to the edge, otherwise the surface is slightly extended in advance.
6) The problem of lifting the knife in the light knife. Lifting the knife is a waste of time, so try to avoid it.
Method 1: Set the knife clearance (small gap)
Method 2: Cover the cover and seal up the knife (small gap)
Method 3: Avoid the gap (large gap)
Method 4: Extend to the same height when contouring
7) The feed problem in the light knife. The first feed must be from the outside of the workpiece to avoid vibration and damage to the workpiece. All light knives must be set to feed.
8) Tool wear problem: When the workpiece is large, multiple tools are required to finish the same workpiece.
