RU19275U1 - TAP - Google Patents

Abstract

A tap consisting of a sampling and calibrating part, characterized in that the sampling part is made in the form of several conically arranged conical surfaces with a gradually increasing largest cone diameter, with a distance between the generators of two adjacent conical surfaces located 1/3 to 1/5 of the thread profile height and the length of each such surface, equal to 3-4 steps of the thread being cut.

Description

20011P6Q04

SHCHILISHMKSHYAM ° °

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TAP

, The solution relates to the processing of metals by cutting and can be applied to tapping in difficult to process materials. In modern industry, super-hard and ultra-strong materials are being used more and more, which, in turn, are very poorly processed by cutting, which is exacerbated by their high plasticity. In addition, many tools (broaches, drills, countersinks, taps, etc.) are made of quick cutters; their steels having insufficiently high hardness, strength, heat resistance, and wear resistance. Thus, one of the main reasons for the failure of a tool is its breakdown. Of particular difficulty is the cutting of internal threads in holes of small diameters. This is due to the limited rigidity and strength of the taps of small diameters, which, in the presence of large cutting forces and torques arising in connection with a large number of simultaneously working teeth in the confined zone of chip formation, its compaction and packaging in grooves, creates extremely unfavorable conditions in the processing zone. Therefore, one of the main directions for solving this problem is the design of new designs of taps that reduce friction and increase tool life. The most used in industry for processing high-strength hard-to-work materials are taps with a staggered tooth arrangement of various modifications. GOST 17927-72 “Taps for machining stainless heat-resistant steels. The main difference between these taps is that the teeth are cut in different variants through one or two teeth, thereby reducing the friction of the tines of the tap on the treated surface. One of the drawbacks of such taps is the real possibility of distortion (reduction) of the thread pitch. To eliminate these

of errors some taps are made with a staggered arrangement of teeth

only on the calibrating part. Another disadvantage of this design is that the working teeth are concentrated in a limited area of the first turns, which leads to frequent breakdowns of the tool.

A modification of staggered taps is a set of three taps. Taps for difficult materials. Information leaflet for design documentation No. 313-86-KS 1-2622-4070, Gorky: Gorky Central Scientific Research Institute, 1986, and at the last - third tapping tooth cutting is not performed. In addition, the difference in average diameter is reduced, starting from the second tap, thereby achieving better centering of the tool when cutting with the second and third taps. The disadvantage of a set of several taps is the low processing performance.

One of the features that reduce the durability of machine taps is the large allowance removed by the teeth on the intake cone and the first tooth on the calibrating part of the tap, since during machining, threading is done with one tap and not with a set of 2-3 pieces.

To eliminate this drawback, a combined (multi-stage) tap is made, the design of which is selected as the prototype of a multi-stage tap. Information leaflet for design documentation No. 879-83 according to copyright certificate 1006119. M.: NIAT, 1983. The first stage is a draft tap, and the second is a fine one. Thus, the tap consists of conical surfaces - intake cones of the draft and finishing stages, and two calibrating parts (draft and finishing). In addition, the first step is made with an additional angle of 120 ° along the profile and a cylindrical ribbon along the outer diameter of the thread 0.18-0.22 in width from the thread pitch. The section between the ends of the intake parts of the steps is made along a length equal to or slightly greater than the length of the cut

carvings. The disadvantage of this tap is the uneven distribution of the load along its length, which when processing, especially viscous materials, leads to the appearance of large cutting forces and torques, and this, in turn, provokes a premature failure of the tool due to breakage.

The objective is to increase tool life.

The technical result is to reduce the magnitude of the torque and, as a consequence, the likelihood of tool breakage due to an increase in the length of the intake part for a more even distribution of the load along its length.

This result is achieved by the fact that in the tap, consisting of the intake and calibrating parts, the intake part is made in the form of several conically arranged conical surfaces with a gradually increasing largest cone diameter, with a distance between the generators of two adjacent conical consecutive surfaces located h 1 / 3-1 / 5 the height of the thread profile and the length of each such surface equal to 4 steps p of the cut thread.

The proposed design of the tap is presented in figure 1 - General view, figure 2 is an enlarged section of the thread profile. The developed tap consists of the intake part 1, the calibrating part 2 and the shank 3. The intake part 1 of the tap is made in the form of several conically arranged conical surfaces with a gradually increasing maximum diameter of the cone. The distance h between the generatrix of each successively conical surface

is 1 / 3-1 / 5 of the height of the thread profile depending on the number of conically located conical surfaces (from 3 to 5), and the length of each conically located conical surface is equal to 3-4 thread steps p depending on the workability of the material. The first thread of thread on each conically located conical surface is completely cut off (as in chess taps). Apart from this first cut thread, each in succession

located conical surface consists of 2-3 threads. When cutting threads in corrosive and heat-resistant steels, it is advisable to use a tap design having 3 threads on each conical surface located consecutively, which is explained by the high viscosity of these materials. The height of the thread profile increases from the first thread of each triple to the last.

A prototype designed for the processing of heat-resistant and corrosive steels, intake 1 and calibrating 2 parts, which are made of high-speed steel P9K5, and the shank 3 is made of steel 40X has the following dimensions:

Tap diameter - Mb.

The degree of accuracy is -G2.

The tap length is 75 mm.

The length of the working part is 20 mm.

Length to the place of welding - 30 mm.

The length of the foot is 10 mm.

The transverse size of the foot is 3.5 mm.

The core diameter is 3mm.

The diameter of the circumference of the depressions is 4.773 mm.

The diameter of the circumference of the peaks is 6.06-o, 02 mm.

The diameter of the three-wire measurement is 6.26-o, oi8 mm.

The radius of the chip groove from the back of the head is 4.8 mm.

The radius of the chip groove from the front surface is 1.2 mm.

Geometric parameters of a tap:

rake angle at 10 ° ± 1 °;

back angle a 4 ° ± 0 ° 30;

reverse taper 0.03 °;

ribbon width 0.6 mm.

According to the thread profile, the oblique oblique is reduced to 1 °;

backing of the surfaces is 3-4 °.

The presented tap works as follows. As noted above, the proposed design has an elongated lead-in cone, which is secured by the complete cutting of one thread of the thread every three threads. The first thread of each follows; three of it is lower than the last thread of the previous three and acts as a guide for the last two threads. The second thread of each three is almost equal in height to the last thread of the previous three. It practically does not participate in cutting, but plays the role of an element performing surface-plastic deformation, which improves the structure and accuracy of the formed thread, and also plays the role of a guide for the third thread of the triple. The stickiness of this element allows to reduce the roughness of the machined threaded surface and increase its service life. Thus, at the same time, two threads of the thread (third threads of each triple) are involved in the metal cutting, i.e. 6 cutting teeth, and not 15-18 (for 5-6 threads) like conventional taps, or 10-13 teeth, like chess taps with cut teeth on the intake cone. Complete and final formation of the thread profile is carried out by the last tooth of the last stage of the intake cone and the subsequent calibrating tap teeth.

Dynamometric and resistance tests carried out in laboratory conditions showed that the proposed tap design reduces the torque by 15-20% and significantly increases the performance of the taps due to the reduction of breakdowns.

The proposed design of the tap allows you to have a more uniform loading of the tool, because all cutting teeth are dispersed over a considerable length of the tool

and when threading, for example, in a standard nut, simultaneously involved teeth located on 2-3 threads. Thus, the proposed tap device can significantly reduce the torque when threading, which increases the tool life and processing productivity, and also improves the accuracy of machining "..

Claims (1)

A tap, consisting of a sampling and calibrating part, characterized in that the sampling part is made in the form of several conically arranged conical surfaces with a gradually increasing largest cone diameter, with a distance between the generators of two adjacent conical surfaces located 1/3 to 1/5 of the thread profile height and the length of each such surface, equal to 3 to 4 steps of the thread being cut.