Abrasive machine for machining a surface of a cylindrical work piece

Information

  • Patent Grant
  • 6461229
  • Patent Number
    6,461,229
  • Date Filed
    Friday, June 29, 2001
    23 years ago
  • Date Issued
    Tuesday, October 8, 2002
    22 years ago
Abstract
Machine for machining an envelope surface of a cylindrical work piece includes a tubular cylindrical housing with a longitudinal axis and having an inner space extending from a first end of the housing, and with an axis offset from the housing axis, a shaft angularly displaceable in the inner space and provided with a recess, and a motor in the recess. A spindle is coupled to the motor and carries a first rotatable tool, a rotatable outer casing encloses the housing, and a lid is arranged for co-rotation with the casing and extends radially over the first end of housing with the lid having a central through opening with the peripheral surface. A second rotated tool is disposed on the peripheral surface, and a support device is adapted to hold the work piece between the tools. The shaft is arranged to cause the first tool to effect radial displacement relative to the second rotated tool.
Description




TECHNICAL FIELD




The present invention relates to an abrasive machine, in particular a grinder for removal of material from an envelope surface of a substantially cylindrical work piece, the machine comprising a rotatably driven tool.




BACKGROUND OF THE INVENTION




Abrasive machines such as grinding machines, lapping machines, honing machines, milling machines, etc., are known in many slightly different designs and embodiments. It is desirous that the machine be compact and as space-saving as possible. For obtaining good machining results, it is on the other hand important that the co-operating parts of the machine have a high mutual stiffness and low tendencies of vibration. These last-mentioned properties are often obtained by giving the machine a heavy bedding and a sturdy and robust design, and therefore these two requirements are often contradictory to the desires for compactness and space-saving properties.




It is known from Swedish Patent Application Nos 9702587-8 and 9702588-6 to provide abrasive machines which at least partially fulfil the above properties. In both said applications, a machine is provided which comprises a tubular cylindrical housing having a longitudinal cylindrical inner space. The cylindrical inner space has a longitudinal axis which is offset from the longitudinal axis of the housing. A shaft is arranged for angular displacement in the cylindrical inner space and has a recess accommodating a motor which is coupled to a rotatable work head. The work head together with the chucking equipment is arranged to hold and rotate a work piece to be treated. The housing is enclosed by a rotatably driven outer casing, with the casing being firmly connected to a lid member having an opening forming at its inner edge a tool, such as a grinding wheel. When the shaft is angularly displaced, the work head is displaced with the work piece in a path allowing the work piece to approach and contact the inner periphery of the tool.




The construction of the machines disclosed in said patent applications implies that the work piece and the tool are supported in a very stable manner since only very short distances are present between the work piece and the shaft which supports the work piece. Furthermore, the arrangement of the tool along the inner periphery of the lid member also implies that the tool exhibits high stability. As a result, these machines exhibit superior precision compared to conventional machines having long support shafts which are subject to vibration and thermal effects.




The machines according to said Swedish patent applications are designed to be able to grind the outer and inner envelope surfaces respectively of annular work pieces which can be gripped by conventional chucking equipment. A need exists, however, for a machine which is capable of removing material from an envelope surface of substantially cylindrical work pieces, for example rollers for bearings, which cannot reasonably be gripped by conventional chucking equipment.




SUMMARY OF THE INVENTION




This object is achieved by means of a machine in particular a grinder for removal of material from an envelope surface of a substantially cylindrical work piece, said machine comprising:




a tubular cylindrical housing extending about a longitudinal axis, said housing having a longitudinal cylindrical inner space extending from a first end of said housing, said cylindrical inner space having a longitudinal axis which is offset from the longitudinal axis of said housing;




a shaft arranged in said inner space for angular displacement therein, said shaft being provided with a recess;




a motor arranged in said recess;




a spindle coupled to said motor, said spindle carrying a first rotatably driven tool;




a rotatable outer casing peripherally enclosing said tubular cylindrical housing;




a lid member associated with said outer casing for co-rotation therewith, said lid member extending radially over a region of said first end of said tubular cylindrical housing with said lid member being provided with a central through opening having a peripheral surface;




a second rotatably driven tool disposed on said peripheral surface of said central through opening of said lid member, and




support means for holding said work piece between said first and second rotatably driven tools;




wherein said shaft is arranged in said inner space such that when said shaft executes an angular displacement in said inner space, said first rotatably driven tool is caused to effect a radial displacement relative said second rotatably driven tool.




Preferred embodiments of the invention are detailed in the dependent claims.











BRIEF DESCRIPTION OF THE DRAWINGS:




The invention will be described in greater detail in the following by way of example only and with reference to embodiments shown in the attached drawings, in which:





FIG. 1

shows in a schematic longitudinal sectional view a first embodiment of the abrasive machine according to the invention;





FIG. 2

is a schematic longitudinal sectional view on a greater scale of a part of the abrasive machine of

FIG. 1

;





FIG. 3

is an end view of the embodiment shown in

FIG. 2

;





FIG. 4

is a view corresponding to

FIG. 2

, though of a second embodiment of the abrasive machine according to the invention;





FIG. 5

is an end view of the embodiment shown in

FIG. 4

;





FIG. 6

is a schematic longitudinal sectional view of a third embodiment of the abrasive machine according to the invention;





FIG. 7

is an end view of the embodiment shown in

FIG. 6

, and





FIG. 8

is a view corresponding to

FIG. 6

, though of a further embodiment of the abrasive machine according to the invention.











DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS:




In the drawings, reference numeral


10


generally denotes an abrasive machine according to the present invention. The machine


10


incorporates a frame


11


which, in the shown embodiment, is designed as a machine bed having a portion


12


for supporting a cantilever housing. The cantilever housing is designed as an externally cylindrical and substantially tube-shaped elongate housing


13


extending about a longitudinal axis. The housing


13


is provided with a longitudinal cylindrical inner space


14


extending from a first end of the housing. The cylindrical inner space


14


has a longitudinal axis which is offset from the longitudinal axis of the cylindrical housing


13


. The cylindrical housing


13


is preferably—although not necessarily—non-rotatably connected to the frame


11


.




Rotatably supported on the outer envelope surface of the cylindrical housing


13


is a rotatable outer casing


15


, a wheel carriage, which is driven by a motor


16


, preferably an electric motor, carried by the housing


13


. Inside the eccentric inner space


14


of the housing, there is provided a shaft


17


which can be revolved or indexed and displaced axially. In the shown embodiment the shaft


17


has a reduced diameter portion


18


projecting out from the housing inner space


14


in a direction towards the supporting portion


12


of the frame


11


. The portion


18


of the shaft thus projecting from the housing is received in a space


19


provided in the supporting portion


12


of the frame


11


, and in which space there is provided means for revolving the shaft


17


, preferably a torque motor


20


, and means for axial displacement of the shaft


17


, preferably a linear motor


21


. The revolving and the axial displacement of the shaft is controlled by one or more sensors


22


and


23


respectively, which preferably are also accommodated in the space


19


of the frame portion


12


. It is evident that the means for revolving and axially displacing the shaft need not be arranged in a manner as shown in the drawings, but may for instance be contained in a recessed portion of the shaft itself.




At its end opposite the reduced diameter portion


18


, the shaft


17


is provided with a recess


24


. The recess extends substantially axially into the shaft


17


and is adapted to receive a motor


25


, for example an electric motor. The motor


25


is provided with a spindle


26


which projects out of the recess


24


. The motor is arranged within the recess such that the spindle


26


extends along an axis which is non-concentric with the longitudinal axis of the shaft


17


. At its end


27


remote from the motor


25


, the spindle


26


carries a first rotatably driven tool


28


.




As is most clearly apparent from

FIGS. 2 and 4

, the rotatable outer casing


15


or wheel carriage, extends axially beyond the first end of the housing


13


and terminates in a peripheral flange


29


. A lid member


30


is firmly connected to the outer casing


15


via the peripheral flange


29


such that the lid member is able to co-rotate with the outer casing. The lid member


30


extends radially over a region of the first end of the tubular cylindrical housing


13


with the lid member being provided with a central through opening


31


having a peripheral surface


32


. A second rotatably driven tool


33


is disposed on the peripheral surface


32


of the central through opening


32


of the lid member


30


. As is apparent from

FIGS. 2

,


3


and


5


, a work piece


34


is arranged to be held between the first and second rotatably driven tools


28


,


33


by support means


35


connected to the shaft


17


.




In accordance with the present invention, the shaft


17


is arranged in the inner space


14


such that when the shaft executes an angular displacement in the inner space, the first rotatably driven tool


28


is caused to effect a radial displacement relative the second rotatable driven tool


33


.




In the embodiments illustrated in

FIGS. 1

to


5


, the abrasive machine


10


is arranged to machine an outer envelope surface of the work piece


34


. Thus, the first rotatably driven tool


28


functions as a control wheel and serves primarily to effect rotation of the work piece


34


and to hold the work-piece against the second rotatably driven tool


33


, the second rotatably driven tool acting as a grinding wheel. As such, the first rotatably driven tool


28


does not necessarily have to have an abrasive surface, though it is advantageous if the surface has a sufficiently high coefficient of friction to ensure rotation of the work piece. The shape of the first rotatably driven tool


28


is selected depending on the shape of the work piece to be machined. In a preferred embodiment, the first rotatably driven tool


28


comprises a first region


36


of first diameter extending a first axial distance and a second region


37


of second diameter extending a second axial distance, the second diameter being greater than the first diameter. In a similar manner, the second rotatably driven tool


33


may comprise a first region


38


of first diameter extending a first axial distance and a second region


39


of second diameter extending a second axial distance, the first diameter being greater than the second diameter. Advantageously, the difference between the first and second diameter of the first rotatably driven tool


28


is substantially equal to the difference between the first and second diameter of the second rotatably driven tool


33


. This described arrangement implies that a work piece


34


of substantially cylindrical shape, though having regions of differing diameter, may have its entire envelope surface machined simultaneously. Nevertheless, it is to be understood that the first and second rotatably driven tools


28


,


33


may also comprise differing numbers of regions of different diameters. Although the first and second rotatably driven tools can have differing axial extensions, maximum usage of the axial surfaces of the first and second rotatably driven tools can be obtained when the first axial distance of the first rotatably driven tool


28


is substantially equal to the first axial distance of said second rotatably driven tool


33


, and the second axial distance of the first rotatably driven tool is substantially equal to the second axial distance of the second rotatably driven tool.




In order to ensure that the work piece


34


is imparted the correct shape, the machine


10


comprises a first dressing tool


40


for dressing the first rotatably driven tool


28


. In the embodiment shown in

FIGS. 2 and 3

, the first dressing tool


40


is carried by the lid member


30


and is annular in form. Thus, the spindle


26


of the motor


25


extends through the first dressing tool


40


. In an alternative embodiment illustrated in

FIGS. 4 and 5

, the first dressing tool


40


is in the form of an arm carried by the tubular cylindrical housing


13


. Advantageously, the machine


10


further comprises a second dressing tool


41


for dressing the second rotatably driven tool


33


, the second dressing tool being in the form of a disc carried by the spindle


26


of the motor


25


. Advantageously, the first and second dressing tools


40


,


41


may comprise a diamond-based abrasive material.




The abrasive machine illustrated in

FIGS. 6

to


8


differs from that of

FIGS. 1

to


5


in that the machine is arranged to machine an inner envelope surface of the work piece


34


. To this effect, the first rotatably driven tool


28


serves as a grinding wheel and is of sufficiently small diameter to pass within the work piece. The second rotatably driven tool


33


thereby serves as a control wheel. In the embodiment shown in

FIGS. 6 and 7

, the work piece is prevented from peripheral migration by the support means


35


connected to the housing


13


in the

FIG. 8

embodiment, on the other hand, the support means extends away from the housing


13


and is instead connected to the frame


11


of the machine. As shown in

FIG. 7

, the machine


10


for machining an internal envelope surface may have a first dressing tool


40


carried by the tubular cylindrical housing


13


. Alternatively, the first dressing tool


40


may be carried by the lid member


30


in a manner corresponding to that shown in FIG.


2


.




With particular reference to

FIGS. 3 and 5

, the machine


10


for machining an external envelope surface is operated in the following manner.




To insert the work piece


34


, the shaft


17


within the tubular cylindrical housing


13


is caused to rotate anti-clockwise to thereby increase the distance between the first and second rotatably driven tools


28


,


33


such that a gap is created which is sufficient to accommodate the work piece. The work piece


34


is inserted into this gap such that it abuts the support means


35


. Thereafter, the shaft


17


is rotated clockwise such that the first rotatably driven tool


28


approaches the second rotatably driven tool


33


until the first rotatably driven tool contacts the work piece. During both the insertion of the work piece


34


and its machining, the rotatable outer casing


15


rotates anti-clockwise at a speed of, for example, 1000 rpm. Due to the connection between the lid member


30


and the outer casing


15


, the second rotatably driven tool


33


is caused to rotate at the same speed. At the same time that the second rotatably driven tool is rotated, the first rotatably driven tool


28


rotates clockwise at a lower speed than the second tool, for example 100 rpm. The differences in rotational speed and direction between the two tools cause the work piece


34


to be pressed against the support means


35


and revolved as machining of the envelope surface of the work piece takes place. Advantageously, at least the second rotatably driven tool


33


comprises an abrasive material such as Cubic Boron Nitride so that the envelope surface of the work piece is abraded. The contact force between the work piece and the two rotatably driven tools can be regulated by rotating the shaft


17


clockwise or anti-clockwise to thereby vary the gap between the two tools.




Once machining is completed, the shaft


17


is displaced anti-clockwise and the work piece


34


is removed and replaced by the next work piece to be machined.




With reference to

FIGS. 6

to


8


, the machine


10


for machining an inner envelope surface is operated in the following manner.




To insert the work piece


34


, the shaft


17


within the tubular cylindrical housing


13


is displaced axially to the left as shown in the drawings so that the first rotatably driven tool


28


becomes axially spaced from the second rotatably driven tool


33


. The work piece


34


is then placed on the second rotatably driven tool


33


and abuts the support means


35


. The shaft


17


is caused to rotate clockwise to thereby increase the distance between the first and second rotatably driven tools


28


,


33


such that the first rotatably driven tool can be inserted within the work piece by an axial displacement of the shaft


17


to the right in the drawings without the first rotatably driven tool fouling the work piece. Thereafter, the shaft


17


is rotated anti-clockwise such that the first rotatably driven tool


28


approaches the second rotatably driven tool


33


until the distance between the first and second rotatably driven tools corresponds to the wall thickness of the work piece


34


. The rotatable outer casing


15


rotates clockwise at a speed of, for example, 100 rpm. Due to the connection between the lid member


30


and the outer casing


15


, the second rotatably driven tool


33


is caused to rotate at the same speed. At the same time that the second rotatably driven tool is rotated, the first rotatably driven tool


28


rotates anti-clockwise at a higher speed than the second tool, for example 30,000 rpm. The differences in rotational speed and direction between the two tools cause the work piece


34


to be pressed against the support means


35


and revolved as machining of the inner envelope surface of the work piece takes place. Advantageously, at least the first rotatably driven tool


28


comprises an abrasive material such as Cubic Boron Nitride so that the inner envelope surface of the work piece is abraded. The contact force between the work piece and the two rotatably driven tools can be regulated by rotating the shaft


17


clockwise or anticlockwise to thereby vary the gap between the two tools.




Once machining is completed, the shaft


17


is displaced clockwise, the work piece


34


is removed and replaced by the next work piece to be machined.




Irrespective of whether the machine


10


is used for machining inner or outer envelope surfaces, dressing of the first and second rotatably driven tools is effected in the same manner. To dress the first rotatably driven tool


28


, the shaft


17


is axially displaced to the left as shown in

FIGS. 2

,


4


,


6


and


8


to cause the first rotatably driven tool to be withdrawn into a space defined by the cylindrical housing


13


and the lid member


30


. By effecting rotation of the shaft


17


, the first rotatably driven tool


28


can be caused to contact the first dressing tool


40


. Naturally, in the

FIG. 2

embodiment, dressing takes place with the lid member


30


, and hence the dressing tool


40


, and the first rotatably driven tool


28


revolving whilst in the

FIG. 4

embodiment only the first rotatably driven tool is revolving.




To dress the second rotatably driven tool


33


, the shaft


17


is axially displaced to the right as shown in

FIGS. 2

,


4


,


6


and


8


to cause the second dressing tool


41


to enter the central opening


31


in the lid member


30


. By effecting rotation of the shaft


17


, the second dressing tool


41


can be caused to approach and contact the second rotatably driven tool


33


. Naturally, dressing takes place with both the second dressing tool


41


and the second rotatably driven tool


33


revolving.




The invention is not limited to the embodiment described above and shown in the drawings. Instead, all modifications and variations within the scope of the appended claims are to be deemed to be covered. For example, the cylindrical housing


13


has been shown having a cylindrical inner space. This space may also have a shape other than a cylindrical shape and the shaft


17


may have any appropriate cross-sectional shape which allows it to be turned or indexed within the inner space of the housing. The portion


18


of the shaft


17


received in the space


19


need not have a reduced diameter. It is further conceivable that the shaft be substituted for a system of articulated links or the like capable of turning or indexing the spindle in an appropriate manner.



Claims
  • 1. An abrasive machine for removal of material from an envelope surface of a substantially cylindrical work piece comprising:a tubular cylindrical housing extending about a longitudinal axis, said housing having a longitudinal cylindrical inner space extending from a first end of said housing, said cylindrical inner space having a longitudinal axis which is offset from the longitudinal axis of said housing; a shaft arranged in said inner space for angular displacement therein, said shaft being provided with a recess; a motor arranged in said recess; a spindle coupled to said motor, said spindle carrying a first rotatably driven tool; a rotatable outer casing peripherally enclosing said tubular cylindrical housing; a lid member associated with said outer casing for co-rotation with said outer casing, said lid member extending radially over a region of said first end of said tubular cylindrical housing with said lid member being provided with a central through opening having a peripheral surface; a second rotatably driven tool disposed on said peripheral surface of said central through opening of said lid member, and support means for holding said work piece between said first and second rotatably driven tools; wherein said shaft is arranged in said inner space such that when said shaft executes an angular displacement in said inner space, said first rotatably driven tool is caused to effect a radial displacement relative said second rotatably driven tool.
  • 2. The machine as claimed in claim 1, wherein said first rotatably driven tool is adapted to act on an outer envelope surface of the work piece.
  • 3. The machine as claimed in claim 1, wherein said first rotatably driven tool is adapted to act on an inner envelope surface of the work piece.
  • 4. The machine as claimed in claim 1, wherein said first rotatably driven tool comprises a first region of first diameter extending a first axial distance and a second region of second diameter extending a second axial distance, said second diameter being greater than said first diameter.
  • 5. The machine as claimed in claim 4, wherein said second rotatably driven tool comprises a first region of first diameter extending a first axial distance and a second region of second diameter extending a second axial distance, said first diameter being greater than said second diameter.
  • 6. The machine as claimed in claim 5, wherein the difference between said first and second diameter of said first rotatably driven tool is substantially equal to the difference between said first and second diameter of said second rotatably driven tool.
  • 7. The machine as claimed in claim 6, wherein said first axial distance of said first rotatably driven tool is substantially equal to said first axial distance of said second rotatably driven tool, and said second axial distance of said first rotatably driven tool is substantially equal to said second axial distance of said second rotatably driven tool.
  • 8. The machine as claimed in claim 1, wherein said machine comprises a first dressing tool for dressing said first rotatably driven tool.
  • 9. The machine as claimed in claim 8, wherein said first dressing tool is carried by said lid member and is annular.
  • 10. The machine as claimed in claim 8, wherein said first dressing tool is carried by said tubular cylindrical housing.
  • 11. The machine as claimed in claim 1, wherein said machine comprises a second dressing tool for dressing said second rotatably driven tool, said second dressing tool being carried by said spindle.
  • 12. The machine as claimed in claim 1, wherein said machine comprises means for axially displacing said shaft with respect to said tubular cylindrical housing.
  • 13. The machine as claimed in claim 12, wherein said shaft is provided with sensors for controlling rotational and axial displacement of said shaft.
Priority Claims (1)
Number Date Country Kind
9804617 Dec 1998 SE
Parent Case Info

This application is a continuation of International Application No. PCT/SE99/02443 filed on Dec. 21, 1999, which International Application was published by the International Bureau in English on Jul. 13, 2000.

US Referenced Citations (6)
Number Name Date Kind
4112624 Uhtenwoldt et al. Sep 1978 A
4656789 Schwar Apr 1987 A
4934104 Ibe Jun 1990 A
5205078 Takara et al. Apr 1993 A
6241590 Heijkenskjold Jun 2001 B1
6322423 Heijkenskjold Nov 2001 B1
Foreign Referenced Citations (4)
Number Date Country
512 250 Feb 2000 SE
WO 9901253 Jan 1999 WO
WO 9901254 Jan 1999 WO
WO 9901255 Jan 1999 WO
Continuations (1)
Number Date Country
Parent PCT/SE99/02443 Dec 1999 US
Child 09/893400 US