RU2205743C1 - Builtup intermittent grindng wheel with axially shifted cutting layer - Google Patents

Abstract

FIELD: manufacture of abrasive tools, possibly for depth peripheral abrasive working of hard-to-grind materials having tendency to occurring flaws such as burnouts and microcracking. SUBSTANCE: builtup intermittent grinding wheel is mounted on spindle by acute angle α relative to plane normal to rotation axis. Grinding wheel includes n abrasive discs eccentrically mounted on spindle by means of eccentric rings with opening shifted relative to outer surface. Eccentricity value is determined depending upon allowance for grinding. Symmetry axes of abrasive discs are arranged by the same central angles β = 360 degrees/n one relative to another. Discs are mounted on spindle at axial gap no more than height half of discs with possibility of periodical rotation around lengthwise axis relative to respective rings. Builtup abrasive wheel with intermittent peripheral axially shifted outer cutting surface completely changes kinematics of grinding process due to eccentric mounting of abrasive discs. EFFECT: lowered temperature of grinding process, enhanced dimensional stability and total strength of tool, improved efficiency and grinding quality. 2 cl, 6 dwg

Description

 The invention relates to the field of manufacturing abrasive tools and can be used for deep peripheral abrasive processing of hard to grind materials predisposed to defect formation in the form of burns and microcracks.

 Known intermittent abrasive wheel made from a standard abrasive disk by cutting grooves on the working peripheral surface [1].

 The disadvantages of this circle are the additional cost of cutting grooves on special or tool grinding machines equipped with dividing devices. At the same time, intermittent grinding wheels of this design reduce the vibration resistance of the processing process, have a reduced strength and area of the working surface, which reduces the dimensional and overall tool life, the quality and productivity of processing, as well as the relatively high consumption of abrasive tools.

 Known prefabricated discontinuous grinding wheel containing a shaft on which are placed two pairs of mounting flanges with beveled ends and installed between the pairs at an angle to the axis of rotation of the abrasive discs, as the latter used cutting wheels installed without axial clearance [2].

 The disadvantage of this circle is the lack of standard thin detachable abrasive discs with the necessary grain size and the necessary bond, which are required for grinding this material. At the same time, thin disks have lower mechanical strength, which limits the cutting conditions and reduces productivity. In addition, the dressing of the wheel is characterized by a relatively high consumption of abrasive, because after wear of any part of the wheel you have to remove the abrasive layer along the entire profile.

 The objective of the invention is to increase the productivity of the grinding process by applying the principle of running contact, the use of standard, common use abrasive discs, increasing durability, vibration resistance and processing productivity, as well as reducing the grinding temperature and consumption of abrasive tools due to a change in the kinematics of the finishing process.

The problem is solved by the proposed intermittent grinding wheel with an axially offset cutting layer, which is mounted on the spindle at an acute angle α to a plane perpendicular to the axis of rotation, while a grinding wheel made of n abrasive discs mounted eccentrically on a common spindle is taken as a grinding wheel using eccentric rings with a displaced hole relative to the outer surface, and the amount of eccentricity is determined by the formula
ε≥h,
where h is the allowance for grinding, and the symmetry axis of the eccentric abrasive discs are located at equal central angles β = 360 ^° / n to each other.

In addition, the disks are mounted on the spindle with an axial clearance of no more than half the height V _{d of the} disks, while the disks are periodically rotated around the longitudinal axis relative to the respective rings by the value of the central angle in the range from α _min = α _d to α _max = β, where α _d - the Central angle, tightening the arc of contact of the disk with the workpiece.

 In FIG. 1 schematically shows the proposed assembled intermittent grinding wheel with an axially offset cutting layer, side view, longitudinal section along BB in FIG. 2; figure 2 is the same, front view along A in figure 1; figure 3 is a processing diagram of a combined intermittent grinding wheel with an axially offset cutting layer (in the cutting zone is an abrasive disk 2); figure 4 - scan trace of a new not worn circle on the work surface; figure 5 is a section along bb in figure 1; Fig.6 is a scan of the trace of a worn and newly filled circle with maximum arcs of contact of the abrasive discs with the treated surface.

 The proposed prefabricated discontinuous grinding wheel with an axially offset cutting layer is composed of several abrasive disks 1,2,3, ..., which are mounted on the spindle eccentrically, and their number is determined by the width of the surface to be grinded and the required performance.

The circle thus formed is mounted on the spindle 4 at an acute angle α to the plane perpendicular to the axis of rotation, using fastening flanges 5 with beveled ends, spacers 6 and nuts 7. Abrasive discs 1,2, 3 can be located both parallel and inclined to a plane perpendicular to the rotational axis, the smooth regulation of the angle α of inclination of disc by using the relative rotation of the flange 5, in which the bevelled ends formed at an angle α _max / 2, wherein rotation of one flange with one end at some yz l respect to the spindle rotation axis must correspond to the same angle of the other flange on the other end of the composite disk.

Spacer washers 6, the thickness of which affects the heat stress of the grinding process, are adopted with a height equal to not more than half the height V _{d of the} abrasive disk.

 An increase in the angle α of the inclination of the circle has a positive effect on the free running of hard-to-grind materials that are prone to defect formation in the form of burns and microcracks.

Another design feature of the intermittent grinding wheel is the eccentric installation of the abrasive disks 1, 2, 3, ... on the spindle 4. The abrasive disk 1 is mounted on the spindle 4 using a special eccentric ring 8, in which the axis of the hole is offset by the amount of eccentricity ε relative to the outer surface , also disk 2 - using ring 9 and disk 3 - using ring 10 etc. In this case, the symmetry axes of the eccentrically mounted abrasive disks are placed at equal central angles β = 360 ^° / n to each other, where n is the number of your abrasive disc. For example, in a circle made up of three disks, the axis of symmetry Г ₁ -О _{ш of the} first disk is positioned at a central angle β = 120 ^° to the axis of symmetry Г ₂ -О _{ш of the} second disk and Г ₃ -О _ш - of the third one (see figure 2) .

When forming a circle, the installation of eccentric abrasive disks at equal central angles β to each other can be carried out, for example, using longitudinal marks Ж ₁ , Ж ₂ , Ж ₃ (see figure 5), which are applied to spindle 4.

In the extreme operating position, for example, of the disk 2 (see FIG. 3), its axis O ₂ —O ₂ (see FIG. 1) is shifted by a distance ε from its geometric axis O _w -O _w , where ε> h, where h is the total allowance left for grinding. Another extreme position of this disk, when it is out of contact with the workpiece and rotated 180 ^o relative to the axis O _W - O _W spindle. As can be seen in figure 3, the second abrasive disk is in contact with the surface to be machined along the arc G ₂ -D ₂ , through β = 360 ^° / n = 120 ^° (for n = 3) the rotation of the spindle, the third disk will come into contact with the workpiece section G ₃ -D ₃ , then the first disk section G- ₁ D ₁ , etc. (see Fig. 4). Thus, an intermittent peripheral cutting surface of the assembly wheel is formed, contributing to a reduction in grinding temperature.

After the profile of each disk is worn in sections G ₁ -D ₁ , G ₂ -D ₂ , G ₃ -D ₃ (see Fig. 3), the disks periodically turn around the axis O _w -O _w relative to the corresponding rings 8, 9, 10 on the value of the central angle in the range from α _min = α _d to α _max = β - the magnitude of the arc, tightening the central angle β, of each disk.

Under these conditions, the circle does not work on the entire peripheral surface, but in small sections G ₁ -D ₁ , G ₂ -D ₂ , G ₃ -D ₃ . Therefore, these sections wear out first, and then other (not worn out) sections are introduced (when the disks are turned through the angle α _e ), etc. This allows you to maintain high enough and the same accuracy of a large batch of parts due to grinding without additional restoration of the profile of the wheel and helps to reduce the consumption of abrasive.

 It should be noted that a circle with worn sections of the profile can be repeatedly used for preliminary grinding with the successive replacement of more worn sections with less worn ones. In this case, the total grinding depth should be less than the height of the profile remaining on the working area of the wheel.

 As the circle is operated, the arc length of the contacts of the protrusions of the disks with the surface being machined increases due to self-sharpening, and the intermittent grinding process stabilizes: vibration decreases, heat stress decreases, surface quality improves, metal removal and productivity increase.

 Abrasive machining around with a discontinuous peripheral outer axially displaced cutting surface allows a 2 ... 2.5 times increase in the cutting depth compared to the traditional one, in which a high-quality machined surface with the required roughness (without burns and microcracks) is obtained due to the intermittent oscillating cutting zone, and reduce the consumption of abrasive by 2 ... 2.4 times.

 A prefabricated abrasive wheel with a discontinuous peripheral axially displaced outer cutting surface changes the kinematics of the grinding process by eccentrically attaching the abrasive discs of the composite wheel and setting them at an angle to the axis of rotation, thereby reducing the grinding temperature, increasing the dimensional and overall tool life, productivity and machining quality.

 The proposed design of an intermittent grinding wheel does not require additional costs, equipment and devices for implementation, it is simple and reliable.

 Grinding wheels with a discontinuous surface are vibration-resistant, since when cutting there are no impacts and depressions smoothly pass into the protrusions, and vice versa.

 The simplicity of the changeover of conventional standard wheels to intermittent indicates the effectiveness of the proposed design of prefabricated intermittent grinding wheels with an axially offset cutting layer.

Sources of information taken into account
1. Yakimov A.V. Grinding process optimization. M.: Mechanical Engineering, 1975 - S. 97-99.

 2. RF patent 2137592, MKI B 24 B 53/00, B 24 D 5/00. The method of forming an intermittent grinding wheel. Stepanov Yu.S., Afanasyev B.I., Borodin V.V. Application 98107295/02, application. 04/14/98, publ. 09/20/99. Bull. 26 is a prototype.

Claims (2)

1. An intermittent discontinuous grinding wheel with an axially offset cutting layer composed of n abrasive disks mounted on the spindle at an acute angle α to a plane perpendicular to the axis of rotation, characterized in that the abrasive disks are mounted eccentrically on the spindle by means of eccentric rings offset from the outside the surface of the hole, and the symmetry axis of the abrasive discs are located at equal central angles β = 360 ^° / n to each other, while the amount of eccentricity is chosen from the condition
ε≥h,
where h is the allowance for grinding. 2. The assembled intermittent grinding wheel according to claim 1, characterized in that the disks are mounted on the spindle with an axial clearance of not more than half the height V _{D of the} disks with the possibility of periodic rotation around the longitudinal axis relative to the respective rings by the value of the central angle in the range from α _min = α _d to α _max = β, where α _d is the central angle, tightening the arc of contact of the disk with the workpiece.

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