SU1303263A1 - Method of working by cutting - Google Patents

Description

one

The invention relates to metalworking and can be used in mechanical engineering enterprises in turning, planing and boring blanks of hard-to-work viscous materials.

There is a known method of machining with a cup cutter, which in the process of cutting rotates forcibly or under the action of contact with a part.

The disadvantage of this method is that most of the heat generated during the cutting process (more than 50%) goes into the cutter. This causes a great heat stress in the tool. In addition, the cutting edge of the tool is cooled at the time of idle run, and then heated at the time of cutting, which creates stresses of different signs in it, and fatigue cracks appear on the tool blade as a result of cyclic stresses, leading to chipping of the blade.

The purpose of the invention is to increase the durability of the cutter.

This goal is achieved by the fact that the cutter periodically stops during cutting, while the time of the cutter in the stopped state is equal to its durability in the specified state, reduced by two to three orders of magnitude.

FIG. 1 shows the installation of the cutter relative to the part; in fig. 2 is a view B in FIG. one; Fig, 3 - scheme of the cutter.

The cutter 1 is installed relative to the axis of the part 2 in the general case at two angles, for example tj and p (Fig. Different options for installing the cutter are possible: | 3 O, 0; 90 °, MO h); cx) O, p O (in this case, the cutter is forced to rotate), etc. The contact angle of the tool with the part, measured along the cutting blade, is H, and the contact width is L

 df, where d is the diameter of the cutter. Points

A and B are the extreme points of contact of the blade of the tool with the part, while This point B of the blade of the tool is located at the shortest distance from the axis of the part and is a shaping point.

The treatment according to the proposed method is carried out as follows.

032632

The cutter contacts with the part and rotates under the action of contact with it or forcibly. The cutter, rotating from the part or from the drive, is given the opportunity to rotate through an angle, or equal to the contact angle H. The turning time of the cutter at the angle F is equal to t. Then the cutter is braked and during the time t., It does not

10 rotates. In the following, the cutter cycle is repeated (Fig. 3).

The operation time of the cutter in the stopped state is determined from the fact that the area of the cutting blade,

15 worn out by a certain amount over time to, should not leave risks on the treated surface during subsequent processing cycles. For different processed materials

20, the amount of wear of the tool at time t,., Is different; it also depends on the cutter material. Practically for steels in normal condition.

25

t

thirty

where T is the cutter's durability in the retarded (stopped) state. For. Verdyh materials, for example

hardened steels, equal to 1 - 30 s.

are chosen

The angle t-p of rotation of the tool during its rotation must be less than the angle of 35 h for the following reasons. When machining with a rotating cutter, when removing an allowance, each blade point passes from point A, the point of greatest thickness of the slice (Fig. 2) to

 points B are the points of the smallest slice thickness (or vice versa), i.e., each blade point has the same volume of the removed metal. According to the proposed method, each point

 Blades only work in a fixed position, i.e. at a certain slice thickness. If H, then there is an area of the blade that does not participate at all in removing the allowance, which

50 increases the load on other parts of the blade. Therefore, and the smaller the difference H -, the more equal is the load on any point of the blade, i.e. over several revolutions of the cutter, as a result of its discrete turns, each point removes the same volume of metal.

As a result of the discrete movement of the cutting edge, the tool life is significantly increased. This is due to the fact that the proposed process combines the advantages inherent in conventional cutting with a prismatic or circular braked (non-rotating) cutter and cutting with a rotating cutting tool.

When cutting with a stopped (non-rotating) cutter according to the proposed method, all the heat released during the cutting process, except for 2.5%, goes to chips and parts. At the same time, the cutting zone AC (Fig. 2), adjacent to its active zone AB, is heated during the cutting time t. AC AB. When the tool is rotated by an AC angle less than or equal to the V angle, the AC zone is heated in operation. Therefore, in this case, much less heat is supplied to the cutter than when cutting with a constantly rotating cutter when the blade point of the cutter passes from point B to point. 2) it cools down considerably and the cutter takes 50% of the total heat released. The smaller the angle H of rotation of the tool when it is rotated, the smaller the temperature differences of the surface of the tool in the cutting zone, the less heat goes into the tool when it is rotated at the time of rotation. It also determines the amount of restriction imposed on the angle of rotation of the tool when it is rotated.

The reduction of heat leaving the cutter, as well as the elimination of temperature differences on the cutting edge of the cutter, eliminates the appearance of fatigue temperature microcracks. As a result, the durability of the cutter during processing by the proposed method is significantly increased (more than 10 times).

0 (, By changing the time t of the tool to turn, the angle H and the time t of the tool to work in a stopped state, it is possible to regulate the amount of heat going to the tool, the part and chips, i.e. to adjust the tool life.

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Editor A. Ogar

Compiled by I. Pavlov

Tehred V. Kadar Proofreader L. Patay

Order 1247/11 Circulation 976 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5

Production and printing company, Uzhgorod, st. Project, 4

FC & .З

Claims (1)

METHOD OF TREATMENT BY CUTTING by a cup cutter rotating forcibly or by contact with the part during the cutting process, 'characterized in that, in order to increase the resistance of the cutter, it is periodically stopped during cutting, while the working time of the cutter in a stopped state is equal to its resistance in the specified state reduced by two to three orders of magnitude. 1 - 130