RU2270078C1 - Milling cutter mounting device - Google Patents

Abstract

FIELD: metal working, namely working of rolling profile of wheel pairs of railway road transport vehicles.

SUBSTANCE: apparatus includes mandrel on which milling cutter is mounted. In order to enhance strength of milling cutter due to gradual in-feed process device includes damping member in the form of disc spring and coupling. The last has riffled end for engaging with reciprocal riffled end of milling cutter; it is mounted on mandrel with possibility of motion in axial direction and it is forced to milling cutter by means of damping member with use of nut. Milling cutter is mounted on mandrel with possibility of rotation in sliding bearings including sleeves and thrust rolling bearings. Other end of milling cutter is forced by means of nut through one of said thrust bearing assemblies.

EFFECT: improved strength of milling cutter.

2 cl, 7 dwg

Description

The invention relates to metalworking, to mechanical engineering technology, in particular to the designs of metal-cutting tools, and can be used in the design and manufacture of mills, for example, for processing the profile of the rolling surface of wheelsets of railway vehicles.

Known prefabricated cutter containing a housing with cutters, damping elements made in the form of thin-walled bushings, and an intermediate disk [1].

The disadvantages of the known milling cutter are the limited technological capabilities, since the milling cutter is intended only for machining planes and does not allow machining bodies of revolution and surfaces of complex shape, which are obtained on CNC machines or using a copier, as well as the complexity of the design, assembly and adjustment - all this does The milling process is expensive and inefficient.

A device for attaching a cutter containing a mandrel on which the cutter is installed [2]. The disadvantages of the known device for mounting the cutter are the limited technological capabilities, since the device does not respond to thermomechanical and other damages encountered in the workpiece and causing vibrations and shock-discontinuous processing, which reduces the quality and productivity of processing, as well as tool breakage.

The objective of the invention is the expansion of technological capabilities for processing bodies of revolution and surfaces of complex shape, as well as simplifying the design, assembly and tuning, increasing productivity, processing quality and tool life by ensuring a smooth embedding process and translating the kinetic energy of the impact into the potential bending energy of an elastic disk spring.

The problem is solved using the proposed device for mounting the cutter, containing a mandrel on which the cutter is mounted, and it is equipped with a damping element in the form of a disk spring and a coupling having a grooved end, designed to interface with a mating groove end made on the cutter mounted on the mandrel axially movable on the splines and pressed against the mill by means of a damping element with a nut, while the mill is mounted on a mandrel with the possibility of rotation on bearings nets in the form of bushings and thrust rolling bearings, and the second end of the cutter is preloaded by a nut through one of the mentioned thrust bearings.

In addition, the device is intended for processing the profile of the surface of the rolling wheelsets of railway vehicles.

The essence of the design of the device for fixing the cutter is illustrated by drawings.

Figure 1 shows the proposed device for mounting a shaped cutter, General view of the Assembly, a partial longitudinal section; figure 2 is a section aa in figure 1; figure 3 is a section bB in figure 1; figure 4 is a cross-section bb in figure 1; figure 5 - element D in figure 1; figure 6 is a diagram of the processing profile of the surface of the rolling wheels of a railway vehicle; in Fig.7 is a section GG in Fig.6.

The proposed device is used for fastening a shaped cutter 1, intended for processing the profile of the surface of the rolling wheels 2 of railway transport. The device comprises a mandrel 3, on which a shaped mill 1 and a damping element 4 are installed. The damping element 4 is taken in the form of a disk spring (for example, according to GOST 3057-79) of high stiffness made of spring steel (GOST 14963-78).

The mill 1 is mounted on the mandrel 3 with the possibility of rotation on sliding bearings in the form of bushings 5 and thrust rolling bearings 6 and 7. One end (for example, left, see figure 1) of the mill 1 is made corrugated with radial triangular flutes 8, the profile angle of which equal to 90 °. This end of the cutter 1 is mated with a counter profile made of grooved radial triangular flutes 9 at the end of the coupling 10. The coupling 10 is mounted on the mandrel 3 on the splines 11 movably in the axial direction and pressed against the mill 1 by a disk spring 4 using a nut 12 and a lock nut 13.

The axial force created by the Belleville spring 4 is received through the clutch 10 and the mill 1 by a thrust rolling bearing 6, which is made in the form of bored tracks for balls on the second end of the mill and on the end of the nut 14, the latter is fixed from self-unscrewing by the lock nut 15. The raceways of the angular contact ball bearings 7 are made on the mandrel 3 and in the hole of the cutter 1.

This design of bearings 6 and 7 allows to reduce the dimensions of the device, however, as bearings 6 and 7 can be taken standard, respectively thrust and angular contact ball bearings.

The device is assembled with a prefabricated cutter 1, in which the required shaped profile is created as an envelope curve to a set of simple-shaped edges of its individual cutting elements, designed to process the profile of the rolling surface of railway wheelset pairs.

The mill [2] consists of a body, in the grooves of which are mounted rails with round hard alloy plates fixed to them with a diameter of 12 ... 16 mm.

To obtain the necessary roughness of the machined surface, the nests for plates on adjacent rails are offset from each other by 1.5 ... 2 mm.

The proposed device with a shaped assembly cutter allows self-adaptation to the heterogeneity of the processed material, to fluctuations in the allowance and other thermomechanical damages that cause an increase in cutting force, and to reduce impact loads on the tool teeth during processing, which will increase the durability of the cutting elements.

An additional degree of freedom - turning relative to the longitudinal axis allows the tooth that came into contact with the workpiece to reduce the angle of rotation of the cutter under the action of the increased cutting force, thereby reducing the thickness of the chip removed.

The reduction in the angle of rotation of the cutter is due to the extraction of the coupling 10 and the instantaneous stop of the cutter with continuous and uniform rotation of the mandrel.

Thus, when faced with an increased allowance or thermomechanical damage on the treated surface, the device with the cutter 1 will react and the flutes 9 of the coupling 10 will disengage from the flutes 8 of the cutter 1, the cutter will begin to slip relative to the coupling.

After passing the area with increased cutting force, slippage will stop and the cutter will continue to rotate uniformly, driven by the coupling.

When the accepted angle of 90 ° of the triangular grooves 8 and 9, the ratio of the cutting force P _z at optimal cutting conditions and the pressing force of the coupling R _d to the cutter due to the elasticity of the damper 4 is as follows:

- at P _z <P _d , the normal operation of the cutter is observed, without slipping and clicking;

- when P _z > P _d there is a slipping of the cutter relative to the coupling and characteristic clicks are heard.

The device with a mill, shown in figures 1-7, are designed to process the profile of the surface of the rolling wheelsets of railway vehicles. However, this design of the device can be effectively used for milling any surfaces of various workpieces.

For machining, when restoring the profile of the rolling surface of railway wheelsets, a different cutting tool is used, for which replaceable plates of different shape and composition are used for the cutting part.

The main obstacle to the effective use of the tool is the thermomechanical damage to the wheel rim that occurs during operation [2].

When the cutter rotates at a constant speed at the time of cutting the tooth into the workpiece at a place of increased hardness, the circumferential feed rate V _{f of the} cutting tooth of the cutter decreases due to the bending of the elastic damper - Belleville spring and the width of the chip removed.

This ensures a smooth embedding process and the transition of the kinetic energy of the impact into the potential energy of the bend of the elastic disk spring.

After the tooth comes out of contact with the workpiece, the previously deformed elastic element returns to its original state, restoring the engagement of the coupling flutes with the cutter flutes.

Due to the presence of an elastic damper, by means of which the circumferential feed rate V _{f of the} cutter is reduced, a smoothly intermittent entry and exit of the cutter teeth out of contact with thermomechanical damages of the processed surface is provided.

During production tests, the rolling surface of the wheelset of the railway transport with thermomechanical damages was processed, the diameter of the wheel blank was 1009 mm, the diameter of the finished parts after processing was 995 mm, the processing was carried out in one pass, so the milling depth was 7 mm.

Induction annealing was carried out before mechanical treatment of the rolling surface; the average hardness in the rolling circle after heat treatment was 289 HB. The wheel is made of steel grade 2 in accordance with GOST 10791-89, the chemical composition of steel: C - 0.60%; Mn - 0.78%; Si - 0.31%; P - 0.03%; S - 0.03%, the rest is iron.

Machining modes: rotation speed of the wheel blank - V _s = 5 m / min (n _s = 1.6 min ^-1 ); cutter rotation speed - V _f = 342 m / min (n _and = 320 min ^-1 ). Shaped mill mounted on the proposed design of the device for mounting it, had the number of teeth z = 10; outer diameter - 340 mm; cup plates RPUX2710MO of hard alloy T14K8.

Processing was carried out on a modernized wheel-turning lathe machine mod. KZh 1836 (manufactured at Kramatorsky KZTS).

The tests established that, with the same performance, the tool life installed on the proposed device increased by 2 ... 2.5 times compared to traditionally fixed milling cutters, the surface roughness improved and the vibration resistance of the process increased, productivity increased and marriage was reduced.

Sources of information taken into account

1 A.S. 1569105 USSR, MKI 5 V 23 C 5/06. Team cutter. V.I. Petrov and others. Application No. 4340167 / 31-08, decl. 12/07/88, publ. 06/07 90. Bull. No. 21.

2 Bogdanov A.F. and others. Restoring the profile of the surface of the rolling wheelsets, S-Pb, PGUPS, 2000, S.50-54, Fig.2.7. - prototype.

Claims (2)

1. The device for mounting the cutter, containing the mandrel on which is installed, a cutter, characterized in that it is equipped with a damping element in the form of a disk spring and a clutch having a grooved end, designed to interface with a mating grooved end made on the cutter mounted on the mandrel axially movable on the splines and pressed against the cutter by means of a damping element with a nut, while the cutter is mounted on a mandrel with the possibility of rotation on sliding bearings in the form of bushings and thrust bearings ah rolling cutter and the second end of the nut is biased in one of said thrust bearings. 2. The device according to claim 1, characterized in that it is intended for processing the profile of the surface of the rolling wheelsets of railway vehicles.

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