1
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 engagement amount.
2
When the amount of back cutting is doubled, the cutting force is doubled;
When the feed rate is doubled, the cutting force increases by approximately 70%;
When the cutting speed doubles, the cutting force gradually decreases;
In other words, if G99 is used and the cutting speed becomes larger, the cutting force will not change much.
3
It can be judged based on the discharge of iron chips whether the cutting force and cutting temperature are within the normal range.
4
When the actual measured value The R of the car may be scratched at the starting position.
5
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 is greater than 500 degrees
Red is greater than 800 degrees
6
FUNAC OI mtc generally defaults to G command:
G69: Not sure
G21: Metric size input
G25: Spindle speed fluctuation detection disconnected
G80: Fixed cycle cancel
G54: Coordinate system default
G18: ZX plane selection
G96 (G97): constant linear speed control
G99: Feed per revolution
G40: Tool nose compensation cancel (G41 G42)
G22: Stored stroke detection is on
G67: Macro program modal call canceled
G64: Not sure
G13.1: Polar coordinate interpolation mode canceled
7
The external thread is generally 1.3P and the internal thread is 1.08P.
8
Thread speed S1200/thread pitch*safety factor (generally 0.8).
9
Manual tool tip R compensation formula: chamfering from bottom to top: Z=R*(1-tan(a/2)) X=R(1-tan(a/2))*tan(a) from top to top Get off the car and change the chamfer from minus to plus.
10
Every time the feed increases by 0.05, the rotational speed decreases by 50-80 rpm. This is because lowering the rotational speed means that the tool wear decreases and the cutting force increases more slowly, thus making up for the increase in cutting force and temperature caused by the increase in feed. Impact
11
The influence of cutting speed and cutting force on the tool is crucial. Excessive cutting force is the main reason for tool collapse. The relationship between cutting speed and cutting force: the faster the cutting speed, the feed remains unchanged and the cutting force decreases slowly. At the same time, the faster the cutting speed, the faster the tool wears, making the cutting force larger and larger, and the temperature will also increase. The higher it is, when the cutting force and internal stress are too great for the blade to bear, the blade will chip (of course there are also reasons for this, such as stress caused by temperature changes and a decrease in hardness).
12
When processing CNC lathes, special attention should be paid to the following points:
(1) At present, economic CNC lathes in our country generally use ordinary three-phase asynchronous motors to achieve stepless speed change through frequency converters. If there is no mechanical deceleration, the spindle output torque is often insufficient at low speeds. If the cutting load is too large, it is easy to get boring. However, some machine tools are equipped with gear gears to solve this problem.
(2) Try to enable the tool to complete the processing of one part or one work shift. Pay special attention to the finishing of large parts to avoid tool changes midway to ensure that the tool can be processed in one go.
(3) When turning threads with a CNC lathe, use a higher speed as much as possible to achieve high-quality and efficient production.
(4) Use G96 as much as possible.
(5) The basic concept of high-speed machining is to make the feed exceed the heat conduction speed, thereby discharging the cutting heat with the iron chips to isolate the cutting heat from the workpiece to ensure that the workpiece does not heat up or heats up less. Therefore, high-speed machining is to choose a very high temperature. Match the cutting speed with high feed and select a smaller back cutting amount.
(6) Pay attention to the compensation of tool tip R.
13
Workpiece material machinability classification table (small P79)
Commonly used thread cutting times and back cutting table (large P587)
Commonly used geometric calculation formulas (Large P42)
Inches and millimeters conversion table (large P27)
14
Vibration and tool chipping often occur during grooving. The root cause of all this is the increase in cutting force and insufficient rigidity of the tool. The shorter the tool extension length, the smaller the clearance angle, the larger the blade area, the better the rigidity, and it can With the greater cutting force, the wider the width of the groove cutter, the cutting force it can withstand will also increase accordingly, but its cutting force will also increase. On the contrary, the smaller the groove cutter, the less force it can withstand, but its The cutting force is also small.
15
Reasons for vibration when turning the groove:
(1) The extension length of the tool is too long, which reduces the rigidity.
(2) The feed rate is too slow, which will cause the unit cutting force to increase and cause large vibrations. The formula is: P=F/back cutting amount*f. P is the unit cutting force and F is the cutting force. In addition, the rotation speed is too fast. The knife will also vibrate.
(3) The machine tool is not rigid enough, which means that the cutting tool can withstand the cutting force, but the machine tool cannot. To put it bluntly, the machine tool cannot move. Generally, new beds will not have this kind of problem. The beds that have this kind of problem are either very old. Or you often encounter machine tool killers.
16
When I was turning a product, I found that the dimensions were fine at the beginning, but after a few hours I found that the dimensions had changed and the dimensions were unstable. The reason may be that the knives were all new at the beginning, so the cutting force was not very strong. It is large, but after turning for a period of time, the tool wears and the cutting force becomes larger, causing the workpiece to shift on the chuck, so the dimensions are often off and unstable.
