EP4005731A1 - Schleifmaschine und verfahren zum betrieb einer solchen schleifmaschine - Google Patents

Schleifmaschine und verfahren zum betrieb einer solchen schleifmaschine Download PDF

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Publication number
EP4005731A1
EP4005731A1 EP21208976.7A EP21208976A EP4005731A1 EP 4005731 A1 EP4005731 A1 EP 4005731A1 EP 21208976 A EP21208976 A EP 21208976A EP 4005731 A1 EP4005731 A1 EP 4005731A1
Authority
EP
European Patent Office
Prior art keywords
workpiece
working
contact surface
contact
support blade
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21208976.7A
Other languages
English (en)
French (fr)
Inventor
Marco Leonesio
Giacomo Bianchi
Jeremi Wójcicki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Consiglio Nazionale delle Richerche CNR
Original Assignee
Consiglio Nazionale delle Richerche CNR
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Consiglio Nazionale delle Richerche CNR filed Critical Consiglio Nazionale delle Richerche CNR
Publication of EP4005731A1 publication Critical patent/EP4005731A1/de
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B5/00—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor
    • B24B5/18—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor involving centreless means for supporting, guiding, floating or rotating work
    • B24B5/22—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor involving centreless means for supporting, guiding, floating or rotating work for grinding cylindrical surfaces, e.g. on bolts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B41/00—Component parts such as frames, beds, carriages, headstocks
    • B24B41/06—Work supports, e.g. adjustable steadies
    • B24B41/067—Work supports, e.g. adjustable steadies radially supporting workpieces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B5/00—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor
    • B24B5/18—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor involving centreless means for supporting, guiding, floating or rotating work
    • B24B5/307—Means for supporting work

Definitions

  • the present invention relates to a grinding machine, in particular of the centreless plunge type and a method for operating such grinding machine to minimize the formation of corrugations on a workpiece, according to the preamble of claim 1 and 6, respectively.
  • the grinding machine which is the object of the present invention is used in the field of mechanical processing for removing shavings.
  • a workpiece is arranged between a driving wheel and a working wheel rotating about a respective axis of rotation, and is supported by a support blade.
  • This particular configuration in which the workpiece is supported on three points, makes the process susceptible to roundness errors, as the workpiece is free to swing while being worked, thus generating a plurality of lobes on its surface.
  • this roundness error depends on geometric working factors such as the working angle and height.
  • working angle means the inclination of the surface of the support blade at the point contacting the workpiece
  • working height means the distance of the centre of the workpiece from the plane containing the axis of rotation of the operating wheel and the medium point of the axis of rotation of the driving wheel.
  • centreless grinding machines that are adapted to minimise the formation of lobes on the workpiece profile by acting on the working height during the process itself.
  • document US 20040209558 A1 discloses a centreless plunge grinding machine adapted to move the blade along a vertical direction to modify the working height, so as to minimise the occurrence of lobes on the workpiece profile.
  • Support blades for known centreless plunge grinding machines have a flat contact surface adapted to support the workpiece as it rotates.
  • the flat contact surface has a constant angle of inclination at every point and can be identified with the working angle.
  • centreless plunge grinding machines are for instance reported in US2897636A and KR102028879B1 .
  • document US2897636A discloses a centreless plunge grinding machine comprising a blade inclination mechanism adapted to allow for grinding processes with different working angles by a same blade. It is worth noting that the blade used in the machine described in document US2897636A is of the standard type and does not have any particular work profile to allow for grinding processes with different working angles.
  • Document KR102028879B1 discloses a centreless grinding machine comprising a support blade configured to contact the workpiece with a single working angle, and an auxiliary support blade adapted to accept the workpiece during automatic loading.
  • centreless grinding machines of the known type do not allow to easily modify the working angle, as this requires the replacement of the support blade or an automatic blade orientation system.
  • the grinding machine disclosed in US2897636A requires to modify the common machines by introducing a specific blade inclination mechanism in order to be able to carry out grinding processes with different working angles by the same support blade.
  • the technical task underlying the present invention is to provide a grinding machine which overcomes the above described drawbacks of the prior art .
  • the grinding machine comprises a first and a second grinding wheel separated by a gap and configured to contact a workpiece, in order to work thereupon as it rotates.
  • the grinding machine further comprises a support blade, arranged in the gap, and adapted to support the workpiece.
  • Such support blade has a contact surface adapted to support the workpiece and a work profile shaped to contact the workpiece at one and only one point at a time.
  • the work profile is shaped to contact the workpiece with different angles in different respective working steps.
  • such working surface and profile of the support blade make it possible to easily vary the working angle.
  • the work profile is shaped to contact the workpiece with at least two different working angles in at least two respective working steps, so that the formation of lobes on the work profile of the workpiece can be minimised by varying the working angle during the process.
  • the present invention relates to a grinding machine 1, in particular a centreless plunge grinding machine.
  • the grinding machine 1 comprises a first and a second grinding wheel 2a, 2b separated by a gap 3 and configured to contact a workpiece 100 to perform a mechanical grinding operation.
  • the first and second grinding wheel 2a, 2b are respectively configured to rotate about a first and a second axis of rotation A-A, B-B to work the workpiece 100 as it rotates.
  • the first and the second grinding wheel 2a, 2b are configured to both contact the workpiece 100 to rotate it about an axis of rotation while removing material from its surface.
  • the first and the second grinding wheel 2a, 2b are arranged in such a way that the first and the second axis of rotation A-A, B-B are at an angle with each other, so that by rotating about their respective axes of rotation they push the workpiece 100 against an abutment pad 5 adapted to hold the workpiece in position while being worked.
  • the first and second grinding wheel 2a, 2b preferably have an axial-symmetric geometry, and extend along the first and second axis of rotation A-A, B-B respectively.
  • the extension of the grinding wheels 2a, 2b along their axis of rotation A-A, B-B is defined as the height of the grinding wheel.
  • the height of the first grinding wheel h M 1 is defined as the extension of the first grinding wheel 2a along the first axis of rotation A-A
  • the height of the second grinding wheel 2b h M 2 is defined as the extension of the second grinding wheel 2b along the second axis of rotation B-B.
  • the first and second grinding wheel 2a, 2b are commonly referred to as the operating wheel and the driving wheel, typically, but not necessarily, the operating wheel has a larger diameter than the driving wheel.
  • the grinding machine further comprises a support blade 4 arranged in the gap 3, i.e. between the first and second grinding wheel 2a, 2b.
  • the support blade 4 has a contact surface 4a to support the workpiece 100 in order to impose a working angle ⁇ .
  • the contact surface 4a of the support blade 4 has a work profile 40a shaped to contact the workpiece at one and only one point at a time.
  • the work profile 40a is shaped to allow contacting the workpiece 100 with different working angles ⁇ in different respective working steps.
  • the support blade 4 is therefore configured to arrange the workpiece 100 with at least a first and a second working angle ⁇ 1 , ⁇ 2 respectively in a first and a second working step.
  • the working angle ⁇ means the inclination of the support blade at a contact point C with the workpiece. More precisely, the working angle ⁇ is defined as the inclination of the tangent line T-T to the work profile 40a drawn at the contact point C of the workpiece 100 with the contact surface 4a. Preferably, the working angle ⁇ is defined by the inclination of the tangent line T-T to the work profile 40a with respect to a plane containing the first axis of rotation A-A and the medium point of the second axis of rotation B-B.
  • the medium point of the second axis of rotation B-B is the medium point of the height of the second grinding wheel h M 2 i.e. the point that divides the height of the second grinding wheel h M 2 into two segments having equal length.
  • the support blade 3 also has the function of supporting the workpiece 100 while it's been worked by imposing a working height and a working height h w .
  • Working height h w means the distance of the centre of the workpiece from the plane containing the first axis of rotation A-A and the medium point of the second axis of rotation B-B.
  • the support blade 4 extends mainly along a vertical direction X-X, and the work profile 40a has at least two tangent lines T-T having different inclinations with respect to the vertical direction X-X.
  • the contact surface 4a comprises at least two flat surfaces having different inclinations.
  • the work profile 40a has at least a first and a second rectilinear stretch 41a, 42a respectively corresponding to the first and second flat surfaces, and having different inclinations with respect to the vertical direction X-X.
  • the support blade 4 of figure 3 allows to easily modify the working angle ⁇ by moving the contact point C of the workpiece 100 with the contact surface 4a from the first to the second flat surface and vice versa.
  • the grinding machine 1 object of the present invention allows to modify the working angle ⁇ without having to replace the support blade 4.
  • the first embodiment of the support blade 4 may comprise more than two flat surfaces, each one having a different inclination and corresponding to a rectilinear stretch of the work profile.
  • the contact surface 4a comprises a curved surface 43
  • the work profile 40a comprises a curved stretch 43a corresponding to the curved surface 43.
  • the contact point C of the workpiece 100 with the contact surface 4a on the curved surface 43 it is possible to vary the working angle ⁇ continuously between a minimum working angle ⁇ min and a maximum working angle ⁇ max .
  • the curved surface 43 therefore allows greater flexibility of use, as it allows to continuously vary the value of the working angle ⁇ .
  • a variation in the working angle ⁇ also corresponds to a variation in the working height h w .
  • the working height h w varies continuously between a maximum h w,max and a minimum working height h w,min , as the working angle ⁇ varies between the maximum ⁇ max and minimum working angle ⁇ min .
  • Each possible contact point C of the workpiece 100 with the contact surface 4a therefore corresponds to a certain working angle ⁇ and a certain working height h w . It is therefore possible to specifically design the contact surface 4a and the corresponding work profile 40a in order to have a certain range of variation of the working angle and height ⁇ , h w .
  • the curved surface 43 as a curve in itself, has a concavity and a radius of curvature.
  • the concavity of the curved surface 43 is turned the opposite way with respect to the workpiece 100, when the latter is resting on the contact surface 40a.
  • the concavity of the curved surface 43 is turned towards the workpiece 100, when the latter is resting on the contact surface 40a.
  • the convex support blade does not impose any lower limits on the radius of curvature of the curved surface 43, as the workpiece 100, regardless of its size, always rests on the contact surface 4a at a single point. Conversely, the concave support blade cannot have a curved surface 43 having a radius of curvature smaller than that of the workpiece 100, otherwise the workpiece 100 would be resting on the contact surface 4a at two separate points, thus making grinding impossible.
  • the concave support blade allows grinding small workpieces 100 with large working angles without generating problems of interference of the first grinding wheel 2a with the support blade 4.
  • the concave support blade unlike the convex support blade, allows to reach the greatest working angles when the contact point between the workpiece 100 and the curved surface 43 is at the first grinding wheel 2a, therefore the first grinding wheel 2a is well spaced apart from the support blade 4.
  • a method for operating a grinding machine in particular the grinding machine 1 of the centreless plunge type described above, is also an object of the present invention.
  • Such method comprises a first working step in which the support blade 4, according to one of the previously described embodiments, is configured to arrange the workpiece 100 at a first working height h w 1 with respect to the plane containing the first axis of rotation A-A and the medium point of the second axis of rotation B-B, according to what has been previously described.
  • the method further comprises a second working step in which the support blade 4 is configured to arrange the workpiece 100 at a second working height h w 2 , which is different from the first working height h w 1 , with respect to the plane containing the first axis of rotation A-A and the medium point of the second axis of rotation B-B.
  • the work profile 40a of the contact surface 4a of the support blade 4 is configured to arrange the workpiece 100 with a first working angle ⁇ 1 in the first working step, and with a second working angle ⁇ 2 other than the first working angle ⁇ 1 in the second working step.
  • the method object of the present invention thus comprises at least two working steps characterised by different working heights and angles h w , ⁇ .
  • the contact surface 4a and the work profile 40a of the support blade 4 are configured to arrange the workpiece 100 in the first working step at the first working height h w 1 with the first working angle ⁇ 1 and in the second working step at the second working height h w 2 with the second working angle ⁇ 2 .
  • the first and second grinding wheel 2a, 2b can be neared/distanced to change the position of the workpiece 100 on the contact surface 4a, and thus the working height and/or angle of h w , ⁇ .
  • the method comprises a transition step interposed between the first and second working steps, in which the distance between the first and second grinding wheel 2a, 2b varies so as to change the first working angle, the height ⁇ 1 in the second working angle ⁇ 2 and the first working height h w 1 in the second working height h w 2 .
  • the transition step can also take place without stopping the working process, i.e. during the grinding process the distance between the grinding wheels 2a, 2b varies gradually so that the working height and angle are continuously varied h w , ⁇ from the values of the first working step to those of the second working step.
  • the workpiece 100 in the first working step the workpiece 100 is resting on the contact surface 4a of the support blade 4 at a first contact point, while in the second working step the workpiece 100 is resting on the contact surface 4a of the support blade 4 at a second contact point other than the first contact point.
  • the contact surface 4a at the first and second contact points is respectively configured to arrange the workpiece 100 at the first working height h w 1 with the first working angle ⁇ 1 and at the second working height h w 2 with the second working angle ⁇ 2 .
  • the method object of the present invention therefore allows to easily carry out a working process with multiple steps, each one having different working angles and heights ⁇ , h w .
  • the method according to the present invention described above may be extended to a generic number "n" of steps, each of which differs from the others in at least the working angle and/or height ⁇ , h w .
  • the method object of the present invention makes it possible to minimise the formation of lobes on the profile of the workpiece by easily varying the working angle ⁇ without having to replace the support blade 4.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Turning (AREA)
  • Grinding Of Cylindrical And Plane Surfaces (AREA)
EP21208976.7A 2020-11-25 2021-11-18 Schleifmaschine und verfahren zum betrieb einer solchen schleifmaschine Pending EP4005731A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT102020000028397A IT202000028397A1 (it) 2020-11-25 2020-11-25 Macchina rettificatrice e metodo per operare tale macchina rettificatrice

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Publication Number Publication Date
EP4005731A1 true EP4005731A1 (de) 2022-06-01

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EP21208976.7A Pending EP4005731A1 (de) 2020-11-25 2021-11-18 Schleifmaschine und verfahren zum betrieb einer solchen schleifmaschine

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EP (1) EP4005731A1 (de)
IT (1) IT202000028397A1 (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2897636A (en) 1956-11-28 1959-08-04 Norman Ind Inc Van Work rest for a centerless grinder
US20040209558A1 (en) 2001-08-14 2004-10-21 Erwin Junker Method and device for centerless cylindrical grinding
KR102028879B1 (ko) 2019-01-23 2019-10-04 조기선 소형 부품 가공용 센터리스 연삭기

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2897636A (en) 1956-11-28 1959-08-04 Norman Ind Inc Van Work rest for a centerless grinder
US20040209558A1 (en) 2001-08-14 2004-10-21 Erwin Junker Method and device for centerless cylindrical grinding
KR102028879B1 (ko) 2019-01-23 2019-10-04 조기선 소형 부품 가공용 센터리스 연삭기

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Publication number Publication date
IT202000028397A1 (it) 2022-05-25

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