Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D7/00—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting otherwise than only by their periphery, e.g. by the front face; Bushings or mountings therefor
  • B24D7/14—Zonally-graded wheels; Composite wheels comprising different abrasives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
  • B24D5/00—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting only by their periphery; Bushings or mountings therefor
  • B24D5/06—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting only by their periphery; Bushings or mountings therefor with inserted abrasive blocks, e.g. segmental
  • B24D5/063—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting only by their periphery; Bushings or mountings therefor with inserted abrasive blocks, e.g. segmental with segments embedded in a matrix which is rubbed away during the grinding process

Definitions

• the invention relates to a grinding wheel for the material-removing machining of at least one workpiece, preferably a grinding wheel for the simultaneous material- removing machining of at least two flat workpieces, wherein the grinding wheel is provided with a base body and a grinding layer arranged thereon for the grinding machining of the at least one workpiece, and wherein the grinding layer comprises a plurality of surface segments, wherein, in each case, a plurality of surface segments is provided both in the circumferential direction and in the radial direction.
• Such grinding wheels in which the hardness of the surface segments is matched to the respective application, are known from practice.
• workpieces such as copper, are known.
• hardness is used as the term for the modulus of elasticity of the material, since the modulus of elasticity correlates with the "hardness” (in the linguistic sense) of a grinding tool as a measure of wear resistance.
• harder is understood as a higher modulus of elasticity value and “less hard” or “softer” designates a lower modulus of elasticity value.
• the modulus of elasticity should be in the range of 40 GPa to 120 GPa, preferably 70 GPa to 105 GPa.
• the modulus of elasticity for determining such values is determined using the resonance method, also known as acoustic hardness testing.
• the elasticity modulus is determined in accordance with DIN EN 843-2 (2006).
• the natural frequency of a test specimen is used in conjunction with sample dimensions and additional material properties (density) to calculate the modulus of elasticity.
• the test specimen is brought into direct contact with a piezo transducer and continuously vibrated over a fixed frequency spectrum (at most between 100 Hz and 100 kHz) [DIN EN 843-2 (2006)]. If the excitation frequency corresponds to the fundamental frequency of the sample, resonance oscillation with maximum amplitude occurs. In this manner, the natural frequency can be determined with the assistance of another piezoelectric sensor.
• the natural frequency is used for a subsequent calculation of the modulus of elasticity according to DIN EN 843-2 (2006).
• the measuring instalment used for this can, for example, be a ZVUK 130 (supplier: ABRASIV, a.s., Pod Borkem 312, 293 01 Mlada Boleslav, Czech Republic).
• a disadvantage of the previously known grinding wheels is that, in practice, situations arise in which, in a short time sequence, hard workpieces and less hard workpieces have to be machined in alternation. This means that either different grinding wheels are used and, in this respect, the grinding machine used has to be modified accordingly. In addition to the increased financial expenses for holding the various grinding wheels available, the set-up times also lead to a reduced useful life of the grinding machine, which also constitutes a financial impairment.
• the object of the invention is to avoid the aforementioned disadvantages and to specify a grinding wheel with which both harder and softer workpieces can be machined with good machining results and good wear behavior of the grinding wheel.
• the grinding layer comprises at least two different types of surface segments, which have different degrees of hardness.
• the different surface segments of the grinding wheel are of the same height when the grinding wheel is unused, and remain at the same height as a result of uniform wear of the surface segments.
• the roughness of the workpiece surface produced which is also negatively affected by scratches from material inclusions in the grinding layer of the grinding wheel, is improved compared to a grinding wheel that only has surface segments with the high degree of hardness.
• a grinding wheel that only has surface segments with the high degree of hardness.
• at least a first group of harder surface segments and a second group of softer surface segments can be provided.
• the hardness of the respective surface segments is influenced by the bond (usually by means of glass frit) and the type and proportion of the grain size (for example, diamond or CBN), as well as by the proportion of the binder (for example, glass frit) and the proportion of a secondary grain, for example aluminum oxide.
• the ratios of the differently hard surface segments to each other can be arbitrary; for example, a distribution of harder surface segments / softer surface segments of 20%/80% up to 80%/20% is possible. Preferably, the distribution can amount to 30%/70% up to 70%/30%. With more than 2 different hard types of surface segments, other divisions are also possible.
• the proportion of harder surface segments can always be higher than the proportion of softer surface segments or vice versa.
• the harder surface segments can have a hardness that is at least 5% harder than the hardness of the softer surface segments, preferably 10% to 20% harder than the hardness of the softer surface segments.
• At least some of the surface segments can be either circular or annular, or even hexagonal.
• the entirety of the surface segments can form a total surface without a high proportion of free spaces between the surface segments.
• At least some of the surface segments can also be quadrangular with straight and/or curved side edges.
• At least two adjacent surface segments may be separated from one another by a recessed area, for example in the form of a groove.
• the recessed areas can also be used, for example, for the intake/removal of coolants and/or lubricants.
• At least one recessed area can extend over the entire radial extension of the grinding wheel and/or, viewed in the radial direction, at least one recessed area can extend only over a partial area of the radial extension of the grinding wheel.
• adjacent surface segments can be arranged directly adjacently to each other (that is, "butt jointed").
• At least one recessed area can extend radially or in the form of an involute.
• At least one recessed area may be filled, at least partially, preferably completely, with a filling material, such as epoxy resin.
• at least one recessed area, preferably each recessed area may have a width of at least 1 mm, preferably 3 mm to 5 mm.
• At least one harder surface segment and at least one softer surface segment can be provided at each radial position of the grinding wheel when viewed in the circumferential direction. This ensures that the desired machining result can be achieved with every radial position of the grinding wheel.
• the proportion occupied by the at least one harder surface segment and the proportion occupied by the at least one softer surface segment can advantageously be of approximate uniform size.
• the material thickness of the surface segments can be at least 3 mm, preferably 5 mm to 10 mm.
• the depth of the recessed areas can correspond to the material thickness of the surface segments, or at least be slightly smaller.
• the invention also relates to a grinding wheel set with two grinding wheels for the simultaneous material -removing machining of both sides of at least two flat workpieces.
• An additional object of the invention in this respect is to avoid the disadvantages mentioned above and to specify a grinding wheel set with which both harder and softer workpieces can be machined with good machining results and good wear behavior of the grinding wheels of the grinding wheel set.
• FIG. 1 shows a grinding wheel 1, which has a base body and a grinding layer arranged thereon for the grinding machining of at least one workpiece not shown in the drawing.
• the grinding layer comprises a plurality of surface segments 2, 3, which are hexagonal in the exemplary embodiment shown, wherein, in each case, a plurality of surface segments is provided both in the circumferential direction and in the radial direction.
• adjacent surface segments 2, 3 are separated from each other by a recessed area 4 in the form of a groove.
• the recessed area 4 viewed in the radial direction, extends over the entire radial extension of the grinding wheel 1.
• the grinding wheel 1 also comprises a base body 5, to which the surface segments 2, 3 are preferably attached by gluing.
• the surface elements 2, 3 of the grinding layer are divided into two different types of surface segments 2, 3, which have different degrees of hardness, and comprise a first group of harder surface segments 2 and a second group of softer surface segments 3.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Polishing Bodies And Polishing Tools (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=62186329

Family Applications (2)

Family Applications Before (1)

Country Status (4)

Family Cites Families (11)

• 2018
  • 2018-05-16 EP EP18172592.0A patent/EP3569360A1/de not_active Withdrawn
• 2019
  • 2019-05-15 WO PCT/IB2019/054039 patent/WO2019220373A1/en unknown
  • 2019-05-15 EP EP19734883.2A patent/EP3793774A1/de not_active Withdrawn
  • 2019-05-15 US US17/052,876 patent/US20210069867A1/en not_active Abandoned
  • 2019-05-15 CN CN201980032630.8A patent/CN112135711A/zh active Pending

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