RU2188118C1 - Apparatus for mounting grinding disc - Google Patents

Abstract

FIELD: machine tool manufacture, possibly high speed and depth grinding of different hard-to-grind materials having tendency to formation of flaws such as burnouts and microcracking. SUBSTANCE: apparatus includes housing and connection flange with corrugated member in the form of two plate springs arranged on ends of connection flange. One end of connection flange and outer bead of housing are provided with cover strips placed in grooves symmetrically formed at both sides in base of one spring. Sleeve rigidly secured to housing is arranged between housing and connection flange. Vibration proofness of system is increased due to application of oscillations whose direction coincides with disc rotation axis upon rotation motion of disc. In the result of such application relief of ground surface is significantly improved due to cutting off protrusions caused by surface roughness and bulks formed at grinding. EFFECT: enhanced quality of ground surface due to increased stability and favorable kinematics of relative motion of disc and part. 7 dwg

Description

 The invention relates to machine tools, processing with an abrasive tool and can be used for high-speed and deep grinding of various hard-grinding materials, prone to defect formation in the form of burns and microcracks.

 Known prefabricated grinding wheel made in the form of fixed on a common shaft with an axial clearance of one relative to the other and inclined to the plane of rotation of the abrasive discs [1].

 A disadvantage of the known prefabricated grinding wheel is the complexity of the processing process, since when grinding wide surfaces, longitudinal and transverse feeds are necessary. When grinding only with a transverse feed, the joints of the disks leave defects on the surface to be treated, which is unacceptable.

 In addition, when grinding wide surfaces, friction increases in the zone of contact of the wheel with the product, as a result of harmful intense vibrations with the frequency of their own bending vibrations of either the product or the grinding spindle with the wheel. Due to the decrease in stability and the occurrence of such harmful vibrations during the grinding process, the known prefabricated grinding wheel quickly loses its cutting properties, increased roughness appears and burns form on the treated surface.

 As a prototype, a device for mounting the grinding wheel at an angle to a plane perpendicular to the axis of rotation of the wheel was selected, and the wheel is mounted on the spindle using an elastic corrugated element [2].

 The disadvantages of the known device for attaching the grinding wheel are the rapid wear of the contacting surfaces of the housing and the elastic sleeve, which are mated on a sliding fit H7 / h6, while the appearance of an increased clearance decreases the stability of the process, harmful vibrations occur that worsen the roughness of the processed surface, the grinding wheel quickly loses cutting properties, burns and microcracks are formed on the surface being polished.

 In addition, the degree of elasticity of the elastic corrugated element for different conditions and processing modes requires different. The design of the prototype does not provide any adjustment of the degree of elasticity, nor the change of the elastic corrugated element.

 The objective of the invention is to reduce heat stress with increased removal of metal, increasing tool life and processing productivity while maintaining the advantages of the intermittent grinding process, as well as increasing the vibration resistance of the process and improving the quality of the surface, in addition, increasing the reliability and the ability to adjust and change the corrugated element when changing processing conditions and cutting conditions.

 The problem is solved using the proposed device for mounting the grinding wheel, comprising a housing and a transitional flange with a corrugated element, the corrugated element is made of two disk springs and installed from the ends of the transitional flange and secured with an additional nut, one of the ends of the transitional flange and the outer flange of the housing is equipped with slats installed in grooves made symmetrically on both sides at the base of one of the cup springs, and between the housing and the adapter flange bush it is fixedly bonded to the housing.

 The design features of the device for mounting the grinding wheel is illustrated by drawings.

 Figure 1 shows the proposed device for mounting the grinding wheel at an angle to the plane of rotation, a longitudinal section; figure 2 is a left view along A in figure 1; figure 3 is a top view along B in figure 1; figure 4, 5 - elastic spring washers; figure 6 - element In figure 1; in Fig.7 is a view along D in Fig. 6.

 A device for attaching the grinding wheel 1 at an angle to the axis of rotation contains a housing 2 mounted on the spindle of the machine, clamping oblique washers 3 and 4, the angle between the ends of which determines the angle of inclination of the wheel to the plane of rotation, the adapter flange 5 in the form of a sleeve with a shoulder on one side and a threaded neck, on the other hand, a nut 6 for fastening the circle 1 on the adapter flange 5, a corrugated element consisting of two cup springs: small 7 and large 8, which are installed from the ends of the adapter flange 5 using an additional nut 9, allowing guide to adjust their firmness. In addition, between the housing 2 and the transitional flange 5 is a sleeve 10, which acts as a sliding bearing, which is pressed onto the housing.

 To transmit torque from the housing 2 to the flange 5 with a circle 1, one of the ends (right, see Fig. 1) of the adapter flange 5 has straps 11 (Figs. 6-7), which are located radially and enter into grooves cut in a plate spring 8, and the outer flange of the housing 2 has straps 12, which are also located radially and enter into the grooves cut in the Belleville spring 8.

The installation of the grinding wheel 1 at an angle α to the plane of rotation and the resulting axial displacement of the cutting peripheral layer leads to the appearance of an additional longitudinal component of the cutting force P _x in the oncoming movement, for example, the left end face (see figure 3) and the workpiece moving with a longitudinal feed S _np . Moreover, the force P _x arises and acts in the longitudinal direction during a half-revolution of the grinding wheel, when its left end faces the workpiece.

Over the next half-turn of the circle, when the movement of the cutting zone in the longitudinal direction coincides with S _{np of the} workpiece, the longitudinal force P _x acting on the left end face drops to zero. The above is true for the grinding process with longitudinal feed, while the elastic disk spring 8 works only in compression and the circle 1 receives longitudinal vibrational displacements in an amount equal to the frequency of rotation of the circle. When changing the direction of supply for compression, a disk spring 7 will work.

When grinding with a transverse feed, a longitudinal additional force P _x alternately arises from the ends of the circle 1, when the ends run onto the workpiece surface to be machined. In this case, the elastic disk springs 7 and 8 work for compression and tension, while the magnitude of the longitudinal vibrational displacements A _pr is increased in an amount equal to the frequency of rotation of the circle. The value of A _pr (figure 1) will depend on the design parameters and stiffness of the elastic disk springs 7 and 8, cutting conditions - S _nр ; S _t2x and the angle of inclination of the circle.

When selecting the magnitude of the amplitude A _{pr of} longitudinal axial vibrations, it is necessary to take into account the average distance between the protrusions of the microroughness formed by abrasive grains. This increases the cutting ability and self-sharpening of the wheel and significantly improves the roughness of the treated surface, due to the principle of originality of the trace, where each subsequent abrasive grain does not fall into the risk-scratches previously cut by the previous grains.

 A grinding wheel, movable by axial vibrations, creates a kinematics favorable for cutting and friction of the relative motion of the abrasive grains of the wheel and the surface of the part being grinded, smooths microroughnesses and strengthens the surface layer of the material.

 Oscillations superimposed on the rotational movement of the circle, the direction of which coincides with the axis of rotation of the circle, increases the vibration resistance of the system during processing. As a result of the overlay, the relief of the machined surface is significantly improved, since the bulk and protrusions arising during grinding are cut off.

 Thus, an improvement in the quality of the machined surface is achieved not only by increasing stability, but also due to the favorable kinematics of the relative movement of the circle and the part.

Example. The bore holes were machined on the mod grinding machine. ZK227V. The material of the workpiece is steel 45 GOST 1050-88 (HB260), the diameter of the machined hole is 130 mm, the cutting tool is an abrasive wheel PV 100 • 40 • 20 24A25PS25K8A. Processing modes: workpiece speed - 40.8 m / min (100 • 1 / min), tool rotation speed - 31.4 m / s, tool rotation speed - 6000 min ^-1 ; cutting depth - 0.8 mm. Coolant - emulsion, processing was carried out in one pass. To measure the vibrations of the machine-tool-tool-tool-workpiece technological system, the low-frequency vibration measuring equipment NVA-1 was used.

 Favorable cutting conditions, vibration resistance, minimal heating of the workpiece were noted, although processing was carried out with increased metal removal performance, the appearance of burns on the treated surface was not recorded. The surface roughness is Ra = 0.63 μm.

 In the grinding process, the proposed device reduces the roughness of the treated surface by 1.5-2 times and increases the resistance of the wheel up to 3 times in comparison with traditional grinding.

Sources of information
1. US patent 1976233, CL. 51-34, 1934.

 2. RF patent 2146586, MKI B 24 V 1/00, 45/00. Grinding method. Stepanov Yu.S., Afanasyev B.I., Borodin V.V. Application 98113502/02 application. 07/15/98. publ. 03/20/2000. Bull. 8 is a prototype.

Claims (1)

 A device for attaching a grinding wheel comprising a housing and a transition flange with a corrugated element, characterized in that the corrugated element is made in the form of two disk springs installed from the ends of the transition flange and secured with an additional nut, one of the ends of the transition flange and the outer flange of the case equipped with slats installed in grooves made symmetrically on both sides at the base of one of the disk springs, and a sleeve is rigidly located between the housing and the adapter flange Mounts with the case.

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