RU2714757C1 - Thread-milling cutter - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to machining of metals by cutting and removal of chips. Threading cutter comprises housing, two cutting plates axially symmetrically fixed on housing, replaceable milling head fixed on working face of housing by means of bayonet joint and tightening screw. Between damper and replaceable milling head damping element is installed. Cutting plates are made in form of thread-cutting combs and fixed on body with possibility of their position and replacement adjustment.

EFFECT: as a result, reducing to one process passage the number of operations required for champing immediately before thread cutting, thread cutting and formation of groove for sealing elements, wider field of application of threaded milling cutter and increase of its productivity and service life.

1 cl, 3 dwg

Description

The present invention relates to the field of metal processing by cutting with chip removal and can be used for chamfering immediately before threading, threading and simultaneously forming grooves for sealing elements (including grooves according to GOST 8820-69) in the workpiece using a machine with numerical program control.

A rotating thread-cutting tool is known from the prior art (see patent for utility model CN 207942025 U, 10/09/2018) designed for sequentially drilling a hole in a part, milling this hole and threading, followed by a chamfer. The tool in the process has axial rotation and longitudinal movement along the axis of the workpiece. The tool movements for processing each subsequent processing element are set separately. The presented scheme for processing typical elements implies chamfering after threading in the hole, which entails the need for a metalwork operation to debur the hole and calibrate the internal thread. In addition, a one-piece metal construction significantly reduces tool life. Since one tool solves several problems, as one of the cutting edges becomes worn out, it becomes necessary to replace the entire tool by removing it from the machine. To quickly resume work, you need to install a new tool. Otherwise, the machine will stand idle until the grinding tool is installed in the turret of the machine. The description of the tool clearly indicates its narrow applicability in production, focusing on the cutting method, which requires frequent tool changes and can only be used in the medium or mass production type.

Also known from the prior art is a cutter for cutting threads (see patent for utility model CN 207681665 U, 08/03/2018), a method for cutting threads and a threaded cutter (see patent for invention RU 2468897 C1, 06/06/2011), taken as a prototype, designed for threading with a turning tool holder with interchangeable cutting inserts installed in the tool grooves. Processing is carried out by a cutter with a two-position arrangement of cutting inserts. The machining process is divided into roughing and finishing passes of the tool. A feature of processing is that the cutting with finishing passes is carried out in the zone of the positive lateral coordinate of the machine with a new cutting insert, and after continuous processing with this insert, it is removed from the socket and installed in a groove on the opposite side of the holder, where this insert is subsequently processed with rough passes . Thread cutting is performed with a rotating part around its axis. The method allows to increase the durability of the tool used by increasing the cutting edges, however, the adjustment speed and the necessary measure of constant adjustment of the control program after the measurement results makes the processing process less productive. A significant disadvantage of the method of threading is that the described tool can only be machined on the internal surfaces and only in hollow cylindrical products. Also, the method and the described cutting tool can only be used on machines with CNC turning group. Another disadvantage of a threaded cutter is the impossibility of machining threaded surfaces in radial holes, in end holes with offset axes relative to the center of the axis of the part, since processing with the specified cutter can be carried out only in holes whose axis coincides with the axis of the workpiece.

The technical problem solved by the present invention is to create a thread mill, devoid of the above disadvantages.

Thanks to the invention, the following technical results are provided:

- reduction to one technological pass of the number of operations necessary for machining the chamfer immediately before threading, threading and forming grooves for the sealing elements;

- expanding the scope of thread milling (the ability to process both internal and external surfaces of parts with the help of lathes, turning-milling and milling groups in any planes depending on the kinematics of the machine and with the type of production from experienced to medium-sized);

- increase in productivity and service life of thread mills.

The indicated technical results are achieved due to a thread mill containing the body, two cutting plates axisymmetrically mounted on the body, a replaceable milling head fixed on the working end of the body using a bayonet joint and a tightening screw. Technological tubules are provided inside the housing and the replaceable milling head for the output of lubricating and cooling process fluids. The bayonet connection provides the alignment and alignment of the holes of the technological tubules of the housing and the replaceable milling head, and the tightening screw ensures reliable fixation of the replaceable milling head on the working end of the housing. At the same time, a damping element is installed between the housing and the replaceable milling head, due to which the quality of the processed surface is improved by damping axial vibrations during milling. In addition, the cutting inserts are made in the form of thread-cutting combs and are fixed to the body with screws, which allows replacing the inserts if necessary without removing the thread mill from the machine. The oval shape of the holes for mounting in the cutting inserts allows you to adjust the position of the inserts, due to which it is possible to adjust the outer diameter of the tool along the cutting edges and threading of various steps.

The implementation of the milling head interchangeable provides the ability to quickly replace it without removing the thread mill from the machine. In addition, using a set of such interchangeable milling heads with various shapes of sharpening of the cutting edges (in accordance with the geometric parameters of the necessary groove), it is possible to form a thread mill in the workpiece any desired groove design option (for example, according to GOST 8820-69, which is most often used at a manufacturing enterprise), which allows the effective use of thread milling even in pilot production.

The design of the thread mill and its principle of operation are illustrated by the following drawings:

- in FIG. 1 shows the appearance of a thread mill;

- in FIG. 2 shows the location of all structural elements of the thread mill;

- FIG. 3 illustrates the principle of operation of a thread mill.

The thread mill contains a housing (Fig. 1, pos. 1), two cutting plates (Fig. 1, pos. 2), axisymmetrically mounted on the housing, a replaceable milling head (Fig. 1, pos. 3), fixed on the working end of the housing at using a bayonet connection (Fig. 2, pos. 5) and a tightening screw (Fig. 1, pos. 4). A damping element is installed between the housing and the replaceable milling head (Fig. 2, item 6), and the cutting inserts are made in the form of thread-cutting combs and are mounted on the housing with the possibility of adjustment of their position and replacement.

The work of the thread mill is carried out as follows: after installing the thread mill in the turret of a numerically controlled machine, the zero point of the tool is adjusted from the working end in the center of the thread mill. Next, the thread mill is brought into the cutting zone to a fixed workpiece (Fig. 3, item 7) along a safe path. The process of processing the part begins with the processing of the chamfer (Fig. 3, pos. 8) under the thread with a replaceable milling head (Fig. 3, pos. 3) of the thread mill. Further, the thread milling cutter, moving along a geometrically complex path, forms a groove (Fig. 3, pos. 9) for the sealing elements using a replaceable milling head (Fig. 3, pos. 3) on the workpiece (Fig. 3, pos. 7) at the same time, cuts the thread (Fig. 3, pos. 10) with the help of cutting inserts (Fig. 3, pos. 2). After, the thread cutter is withdrawn from the cutting zone along a safe path. The entire path of the thread mill (including the involute feed, consisting of cylindrical interpolation of the thread mill and its longitudinal feed, as well as the rotation of the thread mill around its axis), which allows proper processing of various parts, is set by the machine with numerical program control using the appropriate control program, registered in the Register of computer programs on April 12, 2019, certificate of state registration of a computer program No. 20169614781, “The module for generating control programs m of processing curved surfaces based on data with requirements for accuracy and roughness of the machining contour ”(author: Evgeny Petrovich Dyachenko, copyright: Joint Stock Company“ Scientific Research Engineering Institute ”).

The invention allows to reduce to one process pass the number of operations necessary for machining a bevel immediately before threading, threading and forming a groove for sealing elements, to expand the scope of thread milling cutters and increase its productivity and service life.

Claims (1)

A thread mill comprising a housing and two cutting inserts axisymmetrically fixed to the housing, characterized in that it further comprises a replaceable milling head fixed to the working end of the housing by means of a bayonet fitting and a tightening screw, while a damping element is installed between the housing and the replaceable milling head, and the cutting inserts are made in the form of thread-cutting combs and are mounted on the body with the possibility of adjusting their position and replacing them.

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