RU2407625C2 - Method of producing abrasive wheel by water-ice jet - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates machine building and can be used for forming spiral groove on abrasive wheel peripheral working surface. Proposed method comprises using the device made up of housing with mixing chamber. Said chamber incorporates water jet-forming nozzle arranged along the chamber lengthwise axis whereto high-pressure water is fed through union and pipeline. Liquid nitrogen is fed into said nozzle via its union and pipeline. Particles of said liquid nitrogen are entrapped by high-pressure water jet to produce ice particles, hence, to finally form suspension water-ice jet. Abrasive wheel is rotated, while proposed device is located tangentially to wheel working surface and fed lengthwise along abrasive wheel axis, feed pitch corresponding to that of formed spiral groove per one revolution of abrasive wheel.

EFFECT: lower production costs, higher efficiency of machining.

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Description

The invention relates to mechanical engineering technology, to the mechanical processing of materials by a bonded abrasive, to grinding and the formation of a peripheral working cutting layer of a grinding wheel with an ice-water tool.

A known method and device comprising a housing with two bearing bearings, a drive disk with a friction coating, rigidly mounted on a shaft that is installed in the bearing bearings of the housing, a power tool connected to the drive disk and a fixed nut mounted coaxially to the bearing bearings of the housing, the shaft made with a threaded shank in contact with the nut, and the ruling tool is presented in the form of a thin supersonic high-pressure jet of fluid flowing out of a non-rotating nozzle; tightly connected to the inlet channel located in the sleeve, the axis of which is eccentric to the axis of rotation of the drive disk, in which rolling bearings are also eccentrically located, connecting the sleeve and the drive disk with the possibility of their relative rotational and reciprocal radial movement [1].

The known method and device have significant drawbacks: this is a narrow technological capabilities, since the method does not allow you to adjust the parameters of the applied regular microrelief, the low quality of the formation of the working surface of the grinding tool, the low resistance of the machined surfaces, low productivity and high surface roughness, in addition, the device does not allow to form a working surface in the form of a helical cutting surface capable of intensifying otsess grinding.

The objective of the invention is the expansion of technological capabilities of the formation of a regular macrorelief on the working surface, which reduces the likelihood of burns on the workpiece, improving the quality of products and the reliability of the tool, as well as reducing the complexity of the process, reducing manufacturing costs, increasing processing productivity, durability and reducing the roughness of processed surfaces.

The problem is solved by the proposed method of forming a helical groove on the peripheral working surface of the grinding wheel with an ice-water jet, including the use of a device containing a housing with a mixing chamber, inside of which is located on its longitudinal axis a water jet forming nozzle, fed through a nozzle and a pipeline with high-pressure water, and into which liquid nitrogen is supplied through the nozzle and the pipeline, the particles of which are entrained in a high-pressure water jet to form ice particles for final forming slurry vodoledyanoy jet, wherein the grinding wheel rotation report, and the device is placed at a tangent to the peripheral working surface and the cutting range report longitudinal feed of the grinding wheel along the axis at a pitch helical grooves formed in one wheel revolution.

Features of the proposed method are illustrated by drawings.

Figure 1 shows the editing scheme for the formation and formation of a helical groove in the proposed method, a General view from the end face of the grinding wheel; figure 2 is a view along A in figure 1, a General top view of the grinding wheel; figure 3 is a left view along B in figure 1; figure 4 - ice tool, a longitudinal section.

The proposed method and device are designed to form a helical groove 1 with an angle of inclination α, on the peripheral working surface of the grinding wheel 2, which reduces the likelihood of burns and microcracks on the workpiece being grinded (not shown).

The device has the ability to longitudinally move S _PR along the axis of the circle 2, equal to the step t of the formed helical groove 1 for one revolution of the grinding wheel 2, which rotates with a speed V _K. The housing 3 of the device is located so that its longitudinal axis is tangent to the peripheral working cutting surface of the circle 2 and is inclined at an angle a equal to the angle of inclination of the helix being formed.

In the housing 3 there is a mixing chamber 4, inside of which on its longitudinal axis there is a water jet forming nozzle 5. The nozzle 5 is fed with high pressure water through the nozzle 6 and the pipeline 7.

At the same time, liquid nitrogen is supplied into the chamber 4 through its nozzle and pipe 8. In the mixing chamber 4, liquid nitrogen particles are carried away by a high-pressure water jet and enter the outlet pipe 9 with the possibility of formation of ice particles, where a suspension ice-water jet 10 is finally formed.

The high-pressure water source is a unit consisting of a drive pump station, a multiplier type pressure booster and a water supply system (not shown).

The liquid nitrogen supply unit (not shown) consists of a Dewar vessel in which the liquid nitrogen supply is located, a throttle type liquid nitrogen dosing system, and connecting pipelines providing liquid nitrogen to the mixing chamber.

All elements of the ice-water tool subject to significant dynamic and thermal loads (jet forming nozzle, mixing chamber, outlet pipe) are made of hard alloy and also have the ability to quickly replace.

Preparation of the device for forming to work on the proposed method and its work are as follows.

The forming device is mounted, for example, on a support of a lathe. The grinding wheel 2 on the mandrel is fixed in the spindle, for example, using a three-jaw chuck (not shown).

Then set the rotation of the grinding wheel 2 with a speed of V _To . When a high-pressure ice-water jet is supplied with a pressure Р _{Ж, the} process of forming on the peripheral surface of the grinding wheel 2 a regular macrorelief - a helical groove with a depth of l and a step t will begin. The formation of a helical groove can be carried out both in one pass and in several passes, depending on the size of the thickness of the jet and the size of the cross section of the helical groove.

The proposed method and device allows you to adjust the parameters of the formed helical grooves on the working surface of the grinding wheel 2 depending on the processing conditions, fluid pressure, the current diameter of the grinding wheel 2 and its characteristics, which allows the grinding wheel to significantly reduce the temperature and power tension of the grinding process.

The claimed technical solution allows:

- to produce the formation of a regular macrorelief on the surface of the grinding wheel without a defective layer and wear of the ruling tool;

- to exclude dust emission during the operation of the ruling tool.

The processing showed that the roughness parameter of the surfaces processed by the formed grinding wheel decreased to Ra = 0.15 ... 0.32 μm with the initial value Ra = 3.2 ... 6.3 μm, which was carried out at a speed of V _REZ = 35 m / s ( with traditional grinding in solid circles - Ra = 0.32 ... 0.63 μm), productivity has more than doubled compared to traditional grinding, the latter was carried out at a speed of V _REZ = 25 m / s.

To conduct experimental studies on the influence of the main acting factors on the performance of the process of ice formation of the working surface of the circle, a special installation was developed consisting of three main parts: a high-pressure water source, an ice-water tool, and a liquid nitrogen supply unit.

The high pressure water source is an assembly consisting of an oil driven pump station, a multiplier type pressure booster and a water supply system (not shown).

The oil-driven pumping station is designed to supply the consumer, a pressure booster, with hydraulic energy of the oil flow and is an asynchronous electric motor mounted on a common frame, which drives the variable-speed axial piston pump, oil tank, hydraulic control and automation elements, interconnected by hydraulic pipelines. The design of the drive pump station provides a flow of hydraulic fluid - hydraulic oil with a pressure of up to 32 MPa and a flow rate of up to 90 l / min.

The pressure booster is a double-sided hydraulic cylinder that converts low oil pressure at the inlet to high water pressure at the outlet. The multiplication factor of the pressure booster used is 7 units. Reversing the movement of the piston rod is carried out using hydraulic control.

The injection of high-pressure water is carried out alternately by the right and left cavities through pressure valves into a common high-pressure pipeline. From the pressure booster, high-pressure water enters the high-pressure accumulator, designed to smooth out the pressure pulsation, and then to the ice-water tool. A special low-pressure pump unit or water supply network is used to supply the pressure enhancer with low-pressure water filling the cavity of the booster through the suction valves.

Main technical characteristics of the bench installation:

- pressure of high-pressure water - up to 400 MPa;

- the diameter of the jet forming nozzle is 0.0020; 0.005; 0.0080 m;

- the total power of the bench stand electric motors is 40 kW;

- the ratio of the diameter of the collimator and the jet nozzle - 5;

- the mass of the bench installation (excluding working fluids) - 480 kg.

The liquid nitrogen supply unit (not shown) consists of a Dewar vessel in which the liquid nitrogen supply is located, a throttle type liquid nitrogen dosing system, and connecting piping for supplying liquid nitrogen to the ice-water tool. All elements of the liquid nitrogen supply unit have a thermally insulating coating to reduce the intensity of heat exchange with the environment and to prevent icing of pipelines and other elements of the installation.

To study the influence of the geometric parameters of the mixing chamber on the saturation indexes of the jet with ice particles, it is possible to change its internal diameter and the length of the mixing chamber by means of embedded bushings (see Fig. 4).

Example. To assess the quality parameters of the surface layer polished by circles formed by the proposed method and the developed device, experimental studies of the processing of the “body” using formed and traditional circles were carried out. The blank “body” mounted on the magnetic table of the machine was polished on a surface grinding machine mod. 3P722. The blank is made of steel 40X GOST 1050-74, the allowance on the side is t = 0.35 mm.

The body was machined to a height height of 32.7 ± 0.1; the initial roughness parameter Ra = 3.2 μm, achieved - Ra = 0.63; grinding wheel with a formed helical groove, having dimensions: depth - l = 8 mm; width - 8 mm; pitch - t = 16 mm (see Fig. 2), circle mark - PP 14A25PSM2 7K1A 35 m / s; the diameter of the new circle is 450 mm, the width of the circle is 80 mm. Workpieces were processed in the following modes: circle rotation speed V _PEЗ = 35 m / s (1500 min ^-1 ); longitudinal movement speed S _PR = 16 m / min, lateral feed circle S _POP = 15 mm / table travel; supply to the depth of the passage - 0.015 mm, the lubricating-cooling technological mixture supplied to the grinding zone was sulfofresol (5% emulsion).

The required roughness and accuracy of a flat surface was achieved in T _m = 1.75 min (against T _m ^bases = 3.75 min according to the basic version in the conventional grinding treatment at the Oryol steel rolling mill OSPAZ). The control was carried out by an indicator bracket with an indicator ICh 10 B cells. 1 GOST 577-68 and on the profilometer mod. 283 type AII GOST 19300-86. In the processed batch (equal to 100 pieces), no defective parts were found. The deviation of the treated surface from the plane was not more than 0.02 mm, which is permissible.

The proposed method and device that implements the method, expand the technological capabilities of the surface finish treatment of machine parts, improves product quality and tool reliability, reduces the complexity of the process due to processing at high speeds, reduces manufacturing costs, increases processing productivity, durability and reduces the roughness of the processed surfaces.

Information sources

1. RF patent 2105656, B24V 53/12. Device for forming a grinding wheel. Stepanov Yu.S., Afanasyev B.I., Burnashov M.A., Selemenev M.F. Application No. 96110053/02. 05/21/96. 02/27/98. Bull. No. 6.

Claims (1)

A method of forming a helical groove on the peripheral working surface of the grinding wheel with an ice-water jet, comprising the use of a device containing a housing with a mixing chamber, inside of which is located a water jet forming nozzle, fed by means of a nozzle and a pipeline with high pressure water, and into which through a nozzle and a pipeline liquid nitrogen is supplied, the particles of which are carried away by a high-pressure water jet to form ice particles for the final formation of a suspension a tensile water-ice jet, rotation is reported to the grinding wheel, and the device is arranged tangentially to the peripheral working cutting surface of the wheel and the longitudinal feed along the axis of the grinding wheel is equal to the pitch of the formed helical groove in one revolution of the wheel.

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