Influence on cutting temperature: cutting speed, feed rate, back cutting amount.
Influence on cutting force: back cutting amount, feed rate, cutting speed.
Influence on tool durability: cutting speed, feed rate, back cutting amount.
02
When the amount of back engagement doubles, the cutting force doubles;
When the feed rate is doubled, the cutting force increases by about 70%;
When the cutting speed doubles, the cutting force gradually decreases;
In other words, if G99 is used, the cutting speed will increase, but the cutting force will not change much.
03
According to the discharge of iron filings, it can be judged whether the cutting force and cutting temperature are within the normal range.
04
When the actual value X measured and the diameter Y of the drawing is greater than 0.8, the turning tool with a secondary deflection angle of 52 degrees (that is, the commonly used turning tool with a blade of 35 degrees and a leading deflection angle of 93 degrees) The R out of the car may wipe the knife at the starting position.
05
The temperature represented by the color of iron filings: white is less than 200 degrees
Yellow 220-240 degrees
Dark blue 290 degrees
Blue 320-350 degrees
Purple black greater than 500 degrees
Red is greater than 800 degrees
06
FUNAC OI mtc generally defaults to G command:
G69: not sure
G21: Metric size input
G25: Spindle speed fluctuation detection disconnected
G80: Canned cycle cancel
G54: default coordinate system
G18: ZX plane selection
G96 (G97): constant linear speed control
G99: Feed per revolution
G40: Tool nose compensation cancel (G41 G42)
G22: storage stroke detection ON
G67: Macro program modal call cancel
G64: not sure
G13.1: Cancellation of polar coordinate interpolation mode
07
The external thread is generally 1.3P, and the internal thread is 1.08P.
08
Thread speed S1200/pitch*safety factor (generally 0.8).
09
Manual tool nose R compensation formula: from bottom to top, chamfering: Z=R*(1-tan(a/2)) X=R(1-tan(a/2))*tan(a) from top to top Get off the chamfer and change the minus to plus
10
Every time the feed increases by 0.05, the speed decreases by 50-80 revolutions. This is because reducing the speed means that the tool wear decreases, and the cutting force increases slowly, so as to make up for the increase in the feed that causes the cutting force to increase and the temperature to increase. Impact.
11
The influence of cutting speed and cutting force on the tool is very important, and the main reason for the tool to collapse due to excessive cutting force. The relationship between cutting speed and cutting force: when the cutting speed is faster, the feed remains unchanged, and the cutting force decreases slowly. The higher it is, when the cutting force and internal stress are too great for the blade to bear, it will avalanche the knife (of course, there are also reasons such as stress and hardness drop caused by temperature changes)
12
When machining CNC lathes, the following points should be paid special attention to:
1) For the current economical CNC lathes in our country, ordinary three-phase asynchronous motors are generally used to realize stepless speed change through frequency converters. If there is no mechanical deceleration, the output torque of the spindle is often insufficient at low speeds. If the cutting load is too large, it is easy to get bored , but some machine tools have gear positions to solve this problem very well.
2) As far as possible, the tool can complete the processing of one part or one work shift. In the finishing of large parts, special attention should be paid to avoid changing the tool in the middle to ensure that the tool can be processed at one time.
3) When turning threads with CNC lathes, use as high a speed as possible to achieve high-quality and efficient production.
4) Use G96 whenever possible.
5) The basic concept of high-speed machining is to make the feed exceed the heat conduction speed, so that the cutting heat is discharged with the iron filings to isolate the cutting heat from the workpiece, so as to ensure that the workpiece does not heat up or heats up less. Therefore, high-speed machining is to choose a very high cutting speed. The speed is matched with the high feed while selecting a smaller amount of back engagement.
6) Pay attention to the compensation of tool nose R.
13
Workpiece Material Machinability Grading Table (Minor P79)
Commonly used thread cutting times and back engagement scale (big P587)
Calculation formulas of commonly used geometric figures (big P42)
Inches to Millimeters Conversion Chart (Large P27)
14
Vibration and tool breakage often occur during grooving. The root cause of all this is that the cutting force becomes larger and the tool rigidity is not enough. The shorter the tool extension length, the smaller the relief angle, and the larger the blade area, the better the rigidity. With the greater cutting force, but the greater the width of the groove cutter, the cutting force it can withstand will increase accordingly, but its cutting force will also increase. On the contrary, the smaller the groove cutter, the smaller the force it can withstand, but its The cutting force is also small.
15
The reasons for the vibration during the slotting:
(1) The extension length of the tool is too long, resulting in a decrease in rigidity.
(2) The feed rate is too slow, which will cause the unit cutting force to increase and cause large-scale vibration. The formula is: P=F/back cutting amount*f P is the unit cutting force F is the cutting force, and the speed is too fast It will also vibrate the knife.
(3) The rigidity of the machine tool is not enough, that is to say, the tool can bear the cutting force, but the machine tool cannot bear it. To put it bluntly, the machine tool does not move. Generally, new beds do not have this kind of problem. The bed with this kind of problem is either old or old. Either you often encounter machine tool killers.
16
When I was driving a product, I found that the size was fine at the beginning, but after a few hours of work, I found that the size had changed and the size was unstable. The reason may be that the cutting force was not very strong because the knives were all new at the beginning. Large, but after a period of time, the tool wears out and the cutting force becomes larger, causing the workpiece to shift on the chuck, so the size is old and unstable.
17
When using G71, the value of P and Q cannot exceed the sequence number of the entire program, otherwise an alarm will appear: G71-G73 instruction format is incorrect, at least in FUANC.
18
The subroutines in the FANUC system have two formats:
1) The first three digits of P000 0000 refer to the number of cycles, and the last four digits are the program number
2) The first four digits of P0000L000 are the program number, and the last three digits of L are the number of cycles
19
If the starting point of the arc remains unchanged, and the end point is shifted by a mm in the Z direction, the position of the bottom diameter of the arc is shifted by a/2.
20
When drilling deep holes, the drill does not grind the cutting groove to facilitate the chip removal of the drill.
twenty one
If you use a tool holder to drill holes, you can turn the drill bit to change the diameter of the drilled holes.
twenty two
When drilling stainless steel center holes, or when drilling stainless steel holes, the drill bit or center drill center must be small, otherwise it will not move. When drilling with cobalt drills, do not grind the groove to avoid annealing of the drill bit during the drilling process.
twenty three
According to the process, there are generally three types of blanking: one material, two goods, and the whole bar.
twenty four
When an ellipse appears during threading, it may be that the material is loose, and it is enough to use a dental knife to make a few more cuts.
25
In some systems that can input macro programs, macro programs can be used instead of subprogram loops, which can save program numbers and avoid a lot of trouble.
26
If the drill bit is used for reaming, but the hole jumps a lot, then a flat bottom drill can be used for reaming, but the twist drill must be short to increase rigidity.
27
If you directly use a drill bit to drill holes on a drilling machine, the hole diameter may deviate, but if you use a 10MM drill bit to ream the hole on the drilling machine, the diameter of the expanded hole is generally within 3mm. Wire tolerance approx.
28
When turning small holes (through holes), try to make the chips roll continuously and then discharge them from the tail. The main points of chip rolling are: 1. The position of the knife should be raised appropriately; For the amount, remember that the knife should not be too low, or it will be easy to break the chip. If the secondary deflection angle of the knife is large, even if the chip breaks, it will not get stuck on the tool holder. Out of danger.
29
The larger the cross-section of the knife bar in the hole, the less likely it is to vibrate the knife. In addition, a strong rubber band can be tied on the knife bar, because the strong rubber band can play a certain role in absorbing vibration.
30
When turning copper holes, the tip R of the knife can be appropriately larger (R0.4-R0.8), especially when turning the taper, the iron parts may not be fine, and the copper parts will be very stuck.
