EP0252180B1 - Vorrichtung zum Bearbeiten wenigstens einer Umfangsfläche eines runden Werkstückes - Google Patents

Vorrichtung zum Bearbeiten wenigstens einer Umfangsfläche eines runden Werkstückes Download PDF

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Publication number
EP0252180B1
EP0252180B1 EP19860109688 EP86109688A EP0252180B1 EP 0252180 B1 EP0252180 B1 EP 0252180B1 EP 19860109688 EP19860109688 EP 19860109688 EP 86109688 A EP86109688 A EP 86109688A EP 0252180 B1 EP0252180 B1 EP 0252180B1
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EP
European Patent Office
Prior art keywords
workpiece
pressure member
reference surface
rotation axis
bearing
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.)
Expired - Lifetime
Application number
EP19860109688
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German (de)
English (en)
French (fr)
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EP0252180A1 (de
Inventor
Hermann Abbühl
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.)
Fritz Studer AG
Original Assignee
Fritz Studer AG
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Filing date
Publication date
Application filed by Fritz Studer AG filed Critical Fritz Studer AG
Publication of EP0252180A1 publication Critical patent/EP0252180A1/de
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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
    • B24B41/00—Component parts such as frames, beds, carriages, headstocks
    • B24B41/06—Work supports, e.g. adjustable steadies
    • B24B41/061—Work supports, e.g. adjustable steadies axially supporting turning workpieces, e.g. magnetically, pneumatically

Definitions

  • the invention relates to a device for machining at least one circumferential surface of a round workpiece, which has a reference surface running at right angles to its axis of rotation and which is clamped during machining of the circumferential surface in a workpiece clamping device provided with a rotary drive, the workpiece with the reference surface on one to the axis of rotation right-angled flat surface of the workpiece clamping device.
  • the workpiece clamped in a device of the type mentioned at the outset has impact errors and out-of-roundness with respect to the reference surface due to the preceding machining operations, which are to be compensated for by the subsequent machining, in particular grinding. Due to the impact errors or out-of-roundness, the free end of the workpiece causes a wobble during the machining of its peripheral surfaces, which must not be prevented during machining, since otherwise the relationship to the reference surface would be lost. The circumferential surfaces of such workpieces are therefore machined in the workpiece on the fly. In particular, if the area that is not exposed to machining and on which the workpiece is clamped is very small, the machining system has a relatively low rigidity, so that the removal rate is relatively low. If prescribed Workpiece accuracy results in a relatively long machining time.
  • the invention has for its object to improve a device of the type mentioned so that the removal rate increases and thus the machining time can be shortened with a given accuracy.
  • the workpiece is pressed with its reference surface with relatively high forces toward the plane surface during machining, so that it is securely held against the plane surface, even if correspondingly high forces act on the workpiece in the radial direction for a relatively high removal rate.
  • the contact pressure is introduced so that the workpiece does not wobble.
  • the workpiece clamping device then essentially only has the task of centering the workpiece with respect to the axis of rotation, so that the clamping of this workpiece can take place on a circumferential surface which only extends in the direction of the axis of rotation with a relatively short length.
  • the workpiece is subjected to a damping force directed radially to the axis of rotation during machining of its peripheral surface, which damping force acts on the workpiece in the region of the end facing away from the reference surface.
  • This damping makes it possible to increase the stock removal rate even further and to reduce the machining time even further. It is expressly stated that simply because the workpiece is a is exposed to radially directed damping force, an increase in the removal rate is possible without an additional contact pressure being provided by a contact force acting on the free end.
  • a workpiece clamping device which generates a force component in the direction of the plane surface of the workpiece clamping device during clamping, an improvement in the removal rate can be achieved.
  • a prechamber (1) for an internal combustion engine with its outer contour is shown as the workpiece to be machined.
  • the prechamber (1) has a flat reference surface (2) which, after the peripheral surfaces (12, 13, 14) have been machined, must run at right angles to the axis of rotation (15) of these peripheral surfaces (12, 13, 14). This accuracy is obtained by grinding the peripheral surfaces (12, 13, 14). In the previous processing steps of the reference surface (2) and the peripheral surfaces (12, 13, 14), tolerances with respect to the flat reference surface (2) and the peripheral surfaces (12, 13, 14) are still unavoidable.
  • the pre-chamber (1) has a further circumferential surface (16) which adjoins the reference surface (2) via a narrow annular collar (17) and which is not machined.
  • This peripheral surface (16) serves as a clamping surface with which the prechamber (1) is centered over clamping jaws (7) of a workpiece clamping device.
  • the peripheral surface (16) and the collar (17) have only a relatively small extent in the axial direction of the prechamber (1).
  • the pre-chamber (1) is inserted into the workpiece clamping device in such a way that the reference surface (2) lies flat against a flat surface (6) of a spindle (5) which is exactly perpendicular to the axis of rotation (4) of the spindle, which is provided with a rotary drive .
  • the clamping jaws (7) are then advanced in the radial direction of the peripheral surface (16), as a result of which this peripheral surface (16) and thus the entire antechamber (1) are centered on the axis of rotation (4) of the spindle.
  • the previous axis of rotation (15) of the peripheral surfaces (12, 13, 14) is not exactly at right angles to the reference surface (2).
  • the free end (9) of the prechamber (1) therefore performs a wobble movement when the spindle (5) rotates, which can be of the order of 0.3 mm.
  • the exact perpendicularity of the axis of rotation (15) to the reference surface (2) is produced by the machining process to be carried out with the device shown, ie by grinding by means of a grinding wheel (8) which is fed to the prechamber (1) in the radial direction.
  • the grinding wheel (8) causes a tilting moment on the prechamber (1) around its reference surface (2), which tends to lift the reference surface (2) from the plane surface (6). Since the jaws (7) only engage in a relatively short axial distance from the reference surface (2) on the prechamber (1) and since the circumferential surface (16) available for an attack of the clamping jaws (7) has only a short axial extent, the clamping jaws (7) can only counter the tilting moment exerted by the grinding wheel (8) with a relatively small counter torque.
  • the prechamber (1) is loaded with an axial force by which the reference surface (2) contacts the plane surface (6) the spindle (5) is pressed.
  • This contact pressure is introduced into the free end (9) of the prechamber, but in such a way that the wobbling movement of the prechamber (1) and in particular also of the free end (9) is not prevented.
  • a counter tip (3) is provided, which is arranged in particular in a tailstock of a grinding machine, not shown, and which contains a pressure element (11) which, in a conically tapering recess (18), the free end (9) of the prechamber (1) records.
  • the counter tip (3) which is aligned coaxially to the axis of rotation (4) of the spindle (5), has a chamber (19) which surrounds the pressing element (11) radially to the axis of rotation (4) and in which the pressing element (11) has the wobbling movement of the free end (9) of the prechamber (1) can run with.
  • the counter tip (3) has a plane surface (10) which is radial to the axis of rotation (4) and which forms a hydrostatic bearing with the correspondingly formed opposite surface of the pressure element (11).
  • the hydrostatic bearing is supplied with hydraulic fluid via a supply line (20).
  • This pressure fluid for which cooling fluid is preferably used, which is required anyway for grinding, flows out through the hydrostatic bearing into the chamber (19) and out of it through a gap between the pressure element (11) and the counter tip (3) towards the antechamber.
  • the hydraulic medium, especially the coolant, is pumped into the hydrostatic bearing at a pressure of the order of 10 bar.
  • the pressure element (11) carries out the wobbling movement of the free end (9) of the prechamber, so that when the spindle (5) and the prechamber (1) rotate, it moves on a circular path that is central to the axis of rotation (4). Because of its movement, it has to displace the hydraulic fluid in the chamber (19), whereby a damping effect, i. H. a damping force arises. By appropriate dimensioning of the cross section of the chamber (19), this damping movement can be determined with respect to the damping frequency. This determination is made in such a way that the rotational movement of the spindle (5) and thus the wobbling movement of the pressure element (11) is practically undamped.
  • the damping frequency is designed so that it is effective in the range of the machining frequency of the tool, which is approximately a 10-potency higher than the rotational frequency of the spindle (5) and thus the prechamber (1) and the pressure element (11).
  • the workpiece in the case shown the prechamber (1), is pressed during the clamping process with its reference surface (2) through the counter tip (3) to the tarpaulin, to the axis of rotation (4) of the workpiece spindle (5), the plane surface (6) standing perpendicular (Fig. 1).
  • the prechamber (1) is then centered by the clamping jaws attached to the workpiece spindle (5).
  • the grinding wheel (8) is not yet in engagement during this phase (Fig. 1).
  • the workpiece in the embodiment shown the prechamber (1), is set in rotation via the workpiece spindle (5) and the clamping jaws (7), the free end (9) wobbling in accordance with the errors contained before the processing to be carried out now.
  • the wobbling end (9) is then supported by the pressure element, for which purpose a pressure force in the order of 300 to 400 N over the Pressure element (11) is applied in the direction of the flat surface (6) with which the reference surface (2) is pressed against the flat surface (6).
  • the grinding wheel (8) then processes it, as shown in FIG. 2.
  • the embodiment according to FIG. 3 differs from the embodiment according to FIG. 1 initially by the clamping jaws (7 ⁇ ), which are designed in the embodiment according to FIG. 3 in such a way that they correspond to the direction of the arrow shown in FIG. 3 at an angle of about 45 ° obliquely to the axis of rotation (4) of the spindle, so that they exert a force over the peripheral surface (16) and the annular collar (17) with which the reference surface (2) against the plane surface (6) of the spindle ( 5) is pressed.
  • the free end (9) of the prechamber (1) of the embodiment according to FIG. 3 is not loaded with an axial contact force.
  • the free end (9) is received in a recess (22) of a holding element (11 ⁇ ) such that only forces can be transmitted in the radial direction. 1 and 2 is located in a chamber (19) which surrounds it radially and in which a fluid, in particular cooling liquid, is introduced. Due to the wobbling movement which the holding element (11 ⁇ ) carries out with the free end (9) of the prechamber (1), damping forces are exerted on the free end (9). These damping forces make it possible to increase the removal rate compared to a comparable workpiece that is only supported on the fly.
  • FIG. 4 shows part of a device which could be used instead of the counter tip (3) and the pressing element (11) of the exemplary embodiment according to FIG. 1 to fulfill the same function.
  • a pressure element (27) is provided which is fed to the free end (9) of the prechamber with a conically tapering recess and which is supported on the opposite side by means of an axial bearing on a component (28).
  • the axial bearing contains balls (29) as rolling elements.
  • the component (28) is in turn rotatably supported and can be loaded with an axial force in the direction of the arrow, so that the prechamber (1) with its reference surface (2) against the plane surface (6) of the spindle (5) with a force of 300 to 400 N can also be pressed (Fig. 1).
  • the pressing element (27) is held in the radial direction by means of damping elements (30) on a ring (31) attached to the component (28).
  • the damping elements (30) are designed in this embodiment so that they allow the wobble movement of the free end (9) and the pressure element (27), which is supported relative to the component (28) movably via the ball (29).
  • the one-part or multi-part damping element (30) is designed so that it is not yet effective at the rotational frequency.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Grinding Of Cylindrical And Plane Surfaces (AREA)
EP19860109688 1986-07-08 1986-07-15 Vorrichtung zum Bearbeiten wenigstens einer Umfangsfläche eines runden Werkstückes Expired - Lifetime EP0252180B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH2745/86 1986-07-08
CH274586A CH671178A5 (enrdf_load_stackoverflow) 1986-07-08 1986-07-08

Publications (2)

Publication Number Publication Date
EP0252180A1 EP0252180A1 (de) 1988-01-13
EP0252180B1 true EP0252180B1 (de) 1992-10-21

Family

ID=4240655

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860109688 Expired - Lifetime EP0252180B1 (de) 1986-07-08 1986-07-15 Vorrichtung zum Bearbeiten wenigstens einer Umfangsfläche eines runden Werkstückes

Country Status (3)

Country Link
EP (1) EP0252180B1 (enrdf_load_stackoverflow)
CH (1) CH671178A5 (enrdf_load_stackoverflow)
DE (1) DE3687000D1 (enrdf_load_stackoverflow)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2784534A (en) * 1953-07-20 1957-03-12 Heald Machine Co Internal grinding machines
FR1235109A (fr) * 1958-09-12 1960-07-01 Landis Tool Co Dispositif de blocage d'une pièce, actionné par pression, pour les machines à meuler les bagues
NL243373A (enrdf_load_stackoverflow) * 1958-09-15
US3574974A (en) * 1968-05-15 1971-04-13 Skf Ind Inc Hydrostatic work support means for grinders
SE344296B (enrdf_load_stackoverflow) * 1970-06-18 1972-04-10 Lidkoepings Mekaniska Verkstad
CH526368A (de) * 1971-03-19 1972-08-15 Studer Ag Fritz Axial wirkende Anpressvorrichtung

Also Published As

Publication number Publication date
CH671178A5 (enrdf_load_stackoverflow) 1989-08-15
EP0252180A1 (de) 1988-01-13
DE3687000D1 (de) 1992-11-26

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