RU2268111C2 - Milling method by adaptable tool - Google Patents

Abstract

FIELD: machine engineering, working profiles of rolling surfaces of wheel pair of railway road transport vehicles.

SUBSTANCE: method comprises steps of imparting rotation and feed motion along worked surface to blank and to milling cutter in body of which cutters having round cutting tips of hard alloy are mounted. In order to enhance efficiency and quality of working milling cutter is provided with damping member in the form of washer like corrugated spring. Body of milling cutter has trapezoidal radial grooves enlarged to axis of milling cutter and designed for placing said cutters with cutting tips of hard alloy engaged with damping member. Surfaces of radial grooves are faced with bronze porous self-lubricating plates. All said plates except one lateral plate are plane-parallel and they are fixed to body. Said lateral plate is in the form of wedge and it is designed for adjusting gap between it and cutter with use of screw. Cutters in the form of trapezium reciprocal to radial groove of milling cutter body are mounted in said grooves by sliding fit and they are hold in grooves by means of first lid at one end and by means of damping member and second lid at other end. Lids are secured to body by means of screws designed for adjusting elasticity of damping member.

EFFECT: enhanced operational reliability, increased vibration resistance of milling cutter.

2 cl, 7 dwg

Description

The invention relates to metalworking, to mechanical engineering technology, in particular, for processing the surface profile of the rolling wheelsets of railway vehicles.

A known method of milling surfaces of revolution, in which the workpiece and the milling cutter, comprising a housing with cutters with mechanical fastening of the cutting round plates of the hard alloy, report the rotational movement and the feed movement along the machined surface [1].

The disadvantages of this method are the limited technological capabilities, since the mill that implements the method does not allow for smoothness and vibration resistance of the embedding process and subsequent processing - all this makes milling expensive and inefficient.

The objective of the invention is the expansion of technological capabilities for processing bodies of revolution and surfaces of complex shape using CNC machines, copiers, etc., as well as simplifying the design of the tool, assembling and adjusting it, increasing productivity, processing quality and tool life by ensuring a smooth process plunging, vibration resistance and transfer of kinetic energy of impact into potential energy of bending of an elastic plate.

The problem is solved using the proposed method of milling surfaces of revolution, in which the workpiece and the milling cutter, comprising a body with cutters with mechanical fastening of the cutting round plates of hard alloy, report rotational movements and the feed movement along the surface to be machined, and the milling cutter is provided with a damping element made in the form of a washer-shaped corrugated springs, while the cutter body is made with radial grooves of a trapezoidal shape with an extension to the axis of the cutter, in which I mention molded cutters with hard alloy cutting plates attached to them, interacting with a damping element, the surfaces of the radial grooves are lined with bronze porous self-lubricating plates that perform the functions of sliding bearings, while the plates, except for one side, are made plane-parallel and fixed to the body motionless, and the said side the plate is movable in the form of a wedge and is designed to regulate the gaps between it and the cutter with a screw screwed into the threaded hole, os which passes along the contact plane of the side plate in the form of a wedge with the body and half is drilled in the plate and the other half is drilled in the body, while the thread is cut only in the body half of the hole, while the cutters are trapezoidal, the corresponding shape of the radial grooves of the mill body, installed in them on a sliding fit and held in the housing from one end by a cover, and from the other by a damping element and a second cover, while the covers are attached to the body by screws, wrapping or unscrewing which make reg adjusting the elasticity of the damping element to increase vibration resistance and reliability of the cutter.

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

The essence of the proposed method is illustrated by drawings.

Figure 1 shows a milling cutter, with the help of which a method is implemented, a view from a spring-loaded end; figure 2 - a view of figure 1, rotated; figure 3 is a section bB in figure 1; figure 4 is a cross-section bb in figure 1; figure 5 - diagram of the processing and the forces acting on the cutting edge; figure 6 - washer-shaped corrugated spring, front view; Fig.7 - washer-shaped corrugated spring, end view.

The proposed method is intended for milling of surfaces of revolution, in which the workpiece and the milling cutter, comprising a body with cutters with mechanical fastening of the cutting round carbide inserts and a damping element, report rotational movements and a feed movement along the surface to be treated. However, the method can be used in the processing of flat surfaces.

The cutter, with the help of which the proposed method is implemented, comprises a housing 1 with cutters 2 with mechanical fastening of hard alloy cutting round plates 3 and a damping element 4. The housing 1 has radial trapezoidal grooves 5 extending from the axis of rotation, the surfaces of which are lined with bronze porous self-lubricating plates 6, 7 and 8, performing the functions of sliding bearings.

Plane-parallel plates 6 and 7 are fixed (by known methods, for example, glued or with screws) on the housing motionless. The side plate 8 is made in the form of a wedge with an angle a, is movable and serves to regulate the gaps between the cutters 2 and the plates 6, 7 and 8.

Clearance adjustment is carried out using a screw 9 screwed into a threaded hole, the axis of which passes along the plane of contact of the wedge-shaped plate 8 with the body 1 at an angle α to the axis of rotation and half drilled in the plate 8, and the other half in the body 1, while the thread is cut only in the body half of the hole. Half of the drilled hole in the plate 8 is blind, the threaded half of the hole in the housing 1 is through. When adjusting the screw 9 abuts against the end face of the blind hole of the plate 8 and makes it move in the longitudinal direction

Cutters 2 are made of a trapezoidal shape, the reciprocal form of the grooves 5, made in the housing. Cutters 2 are installed in the housing 1 on the plates 6, 7 and 8 on a sliding fit and are held in it by covers 10 and 11.

From one end, the cover 10 is directly attached to the housing 1 by screws 12, and from the other end, the cover 11 through the washer-shaped corrugated spring 4 is also attached to the housing 1 by screws 12. In this case, the protrusions of the corrugations of the spring 4 must contact the cutters 2. The number of protrusions of the spring should be equal the number of cutter cutters.

A combined mill that implements the proposed method allows itself to adapt to the heterogeneity of the processed material, to fluctuations in the allowance and other thermomechanical damages and to reduce impact loads on the teeth of the tool during processing, which will increase the durability of the cutting elements, the reliability of the tool and the vibration resistance of the process. An additional degree of freedom allows the tooth under the action of the cutting force P _{x to} move along the guide plates in the axial direction, in contact with the elastic element and overcoming its resistance. After coming out of contact with the workpiece being processed, the elastic element returns the tooth to its original position. In order to improve the reliability of the design, one side guide plate is made wedge-shaped and movable, which allows you to select and adjust the technological gaps.

The mill shown in figures 1-7, is intended for processing the profile of the surface of the rolling wheelsets of railway vehicles. However, this design 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]. The preload of the elastic element 4 is provided by screws 12.

In this case, before processing, the elasticity of the damping element 4 is controlled depending on the size of the removed allowance, the hardness of the processed material, the nature of thermomechanical damage, etc. by screwing or unscrewing the screws 12 that secure the cover 11 and the washer-shaped corrugated spring 4 to the housing 1 in order to increase vibration resistance and reliability. The determination of the elasticity value of a particular damping element is carried out empirically. According to the proposed method, when the milling cutter rotates at a constant speed at the time of cutting the tooth into the part at a place of increased hardness, the axial displacement of the cutting tooth occurs due to the bending of the elastic spring corrugation and reduction of 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 bending of the elastic spring. After the tooth comes out of contact with the workpiece, the previously deformed elastic element comes to its original state, returning the tooth to its original position.

Due to the presence of elastic tooth supports and its axial displacement due to the bending of the elastic corrugated spring, a smoothly intermittent entry and exit of the cutter teeth from contact with thermomechanical damage to the processed surface is ensured.

Example. On a modernized wheel lathe mod. KZh 1836 (manufactured at Kramatorsky KZTS) treated the rolling surface of a railway wheel pair with thermomechanical damage, the diameter of the wheel blank was 1009 mm, the diameter of the finished wheels 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 _and = 342 m / min (n _and = 320 min ^-1 ); feed per revolution - S _o = 2.7 mm / rev. The mill of the proposed design had the number of teeth z = 10; outer diameter - 340 mm; cup plates RPUX2710MO of hard alloy T14K8.

The tests found that, with the same performance, the resistance of the tool working according to the proposed method increased by 2.1 ... 2.5 times in comparison with the processing of traditional cutters, the roughness of the treated surface improved and the vibration resistance of the process increased.

Information sources

1. DE 4418823 C 1 V 23 C 3/04. (NILES-SIMMONS INDUSNRIENLAGEN GMBH). The method of milling surfaces of revolution. 07/27/1995 - a prototype.

2. Bogdanov A.F. et al. Restoring the profile of the surface of the wheelset: A training manual / A.F. Bogdanov, I.A. Ivanov, M. Sitage. - SPb .: PGUPS, 2000, p. 44.

Claims (2)

1. The method of milling surfaces of revolution, in which the workpiece and the milling cutter, comprising a body with cutters with mechanical fastening of the cutting round carbide inserts, indicate rotational movements and a feed movement along the machined surface, characterized in that the cutter is provided with a damping element made in the form of a washer-shaped corrugated springs, while the cutter body is made with radial grooves of a trapezoidal shape with an extension to the axis of the cutter, in which the said cutters are placed with cutting mounted on them with carbide plates interacting with a damping element, the surfaces of the radial grooves are lined with bronze porous self-lubricating plates that perform the functions of sliding bearings, while the plates, except for one side, are made plane-parallel and fixed to the body motionless, and the said side plate is made movable in the form of a wedge and is designed to regulate the gap between it and the cutter with a screw screwed into a threaded hole, the axis of which passes along the plane of contact a side plate in the form of a wedge with a body and half drilled in the plate, and the other half in the body, while the thread is cut only in the body half of the hole, while the cutters are made in trapezoidal shape, the reciprocal form of the radial grooves of the mill body, installed in a sliding fit and are held in the housing from one end by a lid, and from the other by a damping element and a second lid, while the lids are attached to the housing by screws, wrapping or unscrewing which adjust the elasticity of the damping ele cient to increase the vibration resistance and reliability of the milling operation. 2. The method 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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