FR2529496A1 - APPARATUS AND METHOD FOR MACHINING HOLES IN PIECES AND SIMULTANEOUS, NO-INK RECTIFICATION OF EXTERNAL REVOLUTION SURFACES - Google Patents

Abstract

THE INVENTION RELATES TO AN APPARATUS FOR MACHINING CENTERING HOLES IN A PART WHILE THIS LATTER IS SUBJECT TO A CLASSIC OPERATION OF RECTIFICATION, WITHOUT CENTER, OF EXTERIOR SURFACES OF REVOLUTION. TWO CENTERING HOLE MACHINING TOOLS 38 ARE APPLIED AGAINST THE OPPOSITE ENDS OF A PART AT THE SAME TIME THAT THE OUTSIDE SURFACE OF THE LATTER IS SUBJECT TO A RECTIFICATION OPERATION, WITHOUT CENTER, PERFORMED BY MEANS OF A 12 WHEEL OF RECTIFICATION AND A DRIVE WHEEL 13. THE AXES OF THE SPINDLES 36 CARRYING THE TOOLS 38 ARE RADIALLY OFFSET FROM THE AXIS 16 OF A PREDETERMINED CYLINDER TO BE SHAPED BY PART 14. FIELD OF APPLICATION: MACHINING OF CYLINDRICAL PARTS SUCH AS SHAFTS.

Description

1.

  The invention relates to the field of rectification

  tion, and more particularly the grinding of tree-shaped parts, on which several operations

to be executed.

  In the processing of shaft-like parts, such as drive shafts, centering holes are made by machining or stamping in the opposite ends of such a shaft, so that turning operations can be performed, while that the part is rotated on centers During operations

  following grinding operations without a center of

  outside evolution, some of the surfaces of revolution produced are made concentrically to each other, but the concentricity of these surfaces with the

  centering holes and the central axis of the shaft is destroyed.

  If, for example, a machining operation of gear teeth is carried out after the grinding operation without a center of external surfaces of revolution, the centering holes must be re-established in the workpiece.

  that the machining of the gear teeth can be achieved.

  The difficulty posed by the opera-

  described above and it was determined that it was very

  desirable to have a room which, at the end of the

  centerless grinding line, has holes in

  concentric centering on external surfaces of revolution

  The difficulties encountered during the successive machining operations of the prior art have been avoided and an apparatus and a method of grinding have been devised.

  without centers of external surfaces of revolution and usu-

  swims centering holes in the ends of the shaft,

in the same assembly.

  The operation of machining centering holes

  can be performed at the same time as the

  external surfaces of revolution, or immediately

afterwards.

  The invention is represented in the form of a centerless grinding machine which uses grinding wheels 2. for driving and grinding external surfaces of revolution carried by a base, as well as an axial end stop and a blade of rotation. support of the piece worn by

  the base, between the grinding and grinding wheels

  However, in the machine according to the invention, mounting means are provided on the opposite side faces of the grinding wheel, these mounting means comprising first and second slides arranged fixedly, one in relation to each other,

  on the base and each carrying a movable slide

  In addition, each slider comprises a rotating machining central spindle, the two opposite machining central spindles being mounted so as to have the same extent and

  to be parallel to the axis of rotation of the grinding wheel

  external grinding surfaces The grinding and driving wheels define, with the blade

  of the workpiece, the axis of a predetermined cylinder cir-

  The first and second centering hole machining tools are mounted on the machining spindles and means are provided for moving the sliders.

  axially according to a predetermined operating cycle.

  In one embodiment of the invention, the axes of the center machining pins are radially offset from the axis of the predetermined cylindrical piece so that the centering holes can be made or disengaged while outer surfaces of revolution are made.

  are made by centerless grinding.

  In another embodiment of the invention,

  the axes of the machining pins of the centers coincide with the axis of the predetermined cylindrical part so that the centering holes can be drilled or otherwise

  Machined after rectification operation without center.

  In this other form of machining, a pressure roller assembly is used to apply radial force to the workpiece to maintain it between the work wheel

and the support blade.

  The invention will be described in more detail with reference to the accompanying drawings by way of nonlimiting examples 3 and in which: FIG. 1 is a partial plan view of a centerless grinding machine comprising the apparatus for machining centering holes in a room during a centerless grinding operation according to the invention; Fig. 2 is an elevation of the center machining apparatus for machining an end of a shaft, which elevation corresponds to the direction of the boom 2 of Fig. 1; FIG. 3 is an enlarged partial sectional view along line 3-3 of FIG. 2 of a machining spindle of a centering hole; FIG. 4 is a partial section along the line 4-4 of FIG. 3 of a centering hole machining tool and a centering hole produced with this tool;

  Figure 5 is a diagram of a hydraulic circuit

  that, suitable for a typical tool feed device used in the present invention; Figure 6 is a partial end view of another embodiment of the invention; Figure 7 is an elevation of the form of

  embodiment shown in Figure 6.

  FIG. 1 is a plan view of a centerless grinding machine (10) comprising a base (11) and wheels (12) and (13) rotated and intended respectively for a surface grinding function.

  external revolution and a drive function.

  These wheels are mounted on the base (11) and can be moved relative to each other to the position

  of a predetermined cylindrical part, for example a cylinder

  dre (14) indicated by way of example and formed by the grinding wheels (12) and (13) and a blade (15) for supporting the workpiece mounted on the base (11) of the machine, between the grinding wheels ( 12) and (13) of grinding and driving, in a manner well known to those skilled in the art. A shoulder (14b) of the workpiece is held against an end stop (15a) formed on the bearing blade (15), by the axial thrust of a drive wheel assembly 4., slightly inclined, in a well-known manner In the position shown, the grinding wheels (12) and (13) and the blade (15) of support of the part are said to "frame" a cylindrical part 14, in order to establish the axis (16) of the predetermined circumscribed cylinder (14) to the part. The frame or base (11) of the machine is extended on the opposite sides (17) and (18) of the grinding wheel (12)

  rectification, in order to support two identical mountings

  (19) of centering holes, each comprising, in a general manner, a fixed slide (20) carried by the base (11) and a movable slide (21), arranged on the slide (20) and axially movable relative to the workpiece (14a) The slide (20) described herein includes parallel machined sliding (23) and support bars,

  disposed between end blocks (24) and (25), and the

  movable slat (21) comprises a substantially plate-shaped member (26) to which two bearing blocks (27) and (28) are fitted, which fit in a complementary manner, on the bars (23). ) machining centers comprises an adjustable machining head (29) in which a first block (30) is adjustable in a vertical direction by means of a vertical adjustment screw (31) and a block (32). mounted in the slider (21), and a second block (33) of head is adjustable by means of a horizontal screw (34) and a block (35), similar to the previous ones, the block (35) of adjustment being attached to the first head block (30) A cutting tool head (36) is rotatably mounted on the machining head (29> and has a socket (37) for receiving a tool ( 38) of machining a centering hole, mounted on a rod and which, in this

  case, is represented in the form of a conical grinding wheel.

  A driving force generator (39) is mounted on the second head block (33) and is coupled to drive the spindle (36) carrying the machining tool. The driving force generator (39) shown is an engine. with conventional design, but other motors may be used instead of it At the opposite end of the part (14a)>,

2529496-

  5. a machining assembly (19) is used, and this arrangement will not be described in more detail, being identical to the first assembly described. FIG. 2 is an elevation of the centering hole machining assembly (19) of FIG. 1, this figure also showing the extended base (11) to which is fixed an assembled support (22) of rails. ) are fixed in end blocks (24) and (25)

  of support, and the support blocks (27) and (28) are

  in the forward position on these bars.

  (27) and (28) are attached to the movable slide (26) (re-

  shown in phantom), and this slider includes the cutting head (29), as shown, so that the horizontal and vertical blocks (30) and (33) of the head are

  suitably adjusted to position the tool (38) for

  centering hole formation The slide support (22) carries a fluid cylinder (40) mounted between the bars (23)

  and whose rod (41) of the piston is axially movable.

  The end of this rod (41) is connected to the block (27) of support by a yoke (42) so that a linear movement of the rod (41), under the thrust of a fluid, causes a similar movement of the slider (21) in a linear direction. Figure 3 shows a cylindrical piece

  (14) having a predetermined dimension, supported or

  by the grinding wheel (13), the wheel (12) of

  grinding and the bearing blade (15) of the piece

  predetermined lind (14) establishes a reference axis (16).

  Tapered "A" and "B" to the workpiece support blade and the drive wheel intersect at a point "C" which forms a fork for an oversize piece (14a),

  while being rectified and decreasing in size

  During machining, the axis of the workpiece therefore moves substantially N 1 ie approximately constant line "D" which is the bisector of the internal angle of the fork (the surface of large radius -de the grinding wheel The axis (43) of the centering hole machining tool spindle (36) is offset radially by an amount "e" and is aligned parallel to the axis (16) of the cylinder and to the axis (44) of the machining tool In the example shown, the part (14a) has a roughened or preformed conical opening (45) formed in its end by die-stamping or by drilling. The opening (45) allows entry of the axially movable centering hole machining tool (38) which engages the workpiece (14a) and produces a conical finished hole

  when the rough hole (45) rotates around the conical tool

  (38) In a timed cycle, the final axial position of the centering hole machining tool (38) is reached at the same time as, or immediately after, the final dimension of the rectified outer surface of revolution. , so that the final machining of the centering hole takes place while the part (14 a) is subjected to a pure rotation,

  without radial translation (such a translation is

  during the roughing cycle).

  The section of FIG. 4 shows the conical grinding wheel (38) during its approach, illustrating the eccentricity or the radial offset "e" of the axis (43) of the machining spindle

  centers, relative to the predetermined reference axis.

  It is best to use a machining tool that retains its shape on a number of parts. Therefore, when using a grinding wheel as a tool, it is best to use a hard grinding wheel to avoid to continually refine it. During machining tests, it appeared that cubic boron nitride grinding wheels, available under the trademark "Borazon", are not suitable.

  quite good at mild steels, but work well.

on hard steel parts.

  Diamond impregnated wheels have been used successfully and, in general,

  tend to last longer than other grinding wheels

  fication. Tapered cutting tools with sharp edges 7.

  multiples (either very fast steel or

  bure) were used to mill the centering holes to the correct size and concentrically to the surfaces

external of revolution finished.

  It is also possible to use a conventional centering drill mounted on the spindle holder L in

  a variant of the invention, described below.

  FIG. 5 is a diagram of an electronic circuit

  hydraulic system which is simplified in form to

  The pressure is from a pressurized fluid supply source in the machine (not shown) and is applied to a pressure port (46) of a solenoid valve. Four-way valve (47) which is biased by springs in a centered position in which pressure is returned by a discharge port (48) to the hydraulic reservoir (49), and lines (50) and (51) terminating at the cylinders are locked to prevent any flow When it is desired to advance the tool (38) for producing the centering hole towards the workpiece, the spool (52) for feeding

  the four-way solenoid valve (47) is energized so as to

  applying the pressure through the line (50) at one end of the respective feed rolls (40) to advance the slides (21). The latter advance at a speed

  determined because the discharge fluid flows through the

  picks (51) passing through a pressure compensated flow control valve (53), returning to the reservoir (49) The check valve (54) is connected in parallel with the control valve (53) and the valve (54) is closed when this pipe (51) is discharged to the reservoir (49) The slides (21) advance until

  a trigger (55) (attached to one of the

  buckets) door against a switch (56) end of stroke (fixed to the slide) At this time, the coil (52) advance

  is excited and the rewind spool (57) is excited

  When the coil (57) is energized, the four-way solenoid valve (47) is moved to its leftmost position shown in FIG. 8. Position in which the pressure is transmitted through the valve (47). ) and via the line (51), and freely applied via the check valve (54), bypassing the flow control valve (53), so as to reduce the flow rate.

  piston rod (41) in its initial retracted position.

  The pipe (50) connected to the discharge end of the jack (40) is then freely connected to the hydraulic reservoir (49). In its return stroke, the slide (21) moves until a second stop ( 58)

  door against a second switch (59) limit switch.

  When the latter is actuated, the fast return coil (57) is de-energized and the four-way solenoid valve (47) is centered by its springs in the middle position shown in FIG. 5. It may be noted that various fluids can be used, such as oil for hydraulic circuits, which requires a reservoir, or air that can be discharged to the atmosphere It can also be noted that various hydraulic valves can be used in combination to vary the advance speed of the sliders, including to produce a fast approach movement during the cycle The flow control valve is set to closely match the end of the feed position, i.e. the position of grinding external surfaces of

revolution to the final diameter.

  In another embodiment of the invention,

  As shown in FIG. 6, a pressure roller (60) is carried by a lever (61) than a piston rod (63) connected to the outer end (64) of the lever (61).

  using a clevis, rotates in the middle (62).

  The piston rod (63) can slide in a cylinder (65) which is mounted by means of a yoke on a fixed base such as the blade (15) for supporting the workpiece A at certain times, the roller (60 ) is applied against the workpiece (14)

and is far away from it.

  Figure 7 shows the applied roller (60) 9.

  against the workpiece (14), and the cutting tool (38) is

  as coaxial with the workpiece (14).

  According to this wish of the user, the workpiece (14) can be held by the roller (60) against a non-rotatable drive wheel (13) and a coaxial machining tool (38), such as that a drill to center, can be

  used to machine the workpiece (14), before or after the

  the outer surfaces of revolution, or else

  both before and after this rectification.

  Similarly, according to the wishes of the user, the realization of a centering hole can be performed after an operation of grinding external surfaces of revolution, but by means of a

  off-center machining tool (38), for example a grinding wheel.

  In this case, the roller (60) is applied against the piece (14), but the latter is rotated by

  a driving wheel (13) which rotates.

  It should therefore be noted that various combinations of

  sounds of machining tools, pinch rollers, drive wheel rotations and tool eccentricities

  may be used in relation to an opera-

  rectification of external surfaces of revolution

  to perform center hole machining operations

  before, during and after the grinding.

  It goes without saying that many changes can be made to the writing device and represented

  without departing from the scope of the invention.

10.

Claims (6)

  An apparatus for machining centering holes in a workpiece while performing an operation of grinding external surfaces of revolution in a centerless grinding machine (10), comprising a base (11),   wheels (12, 13) which are rotated   The invention concerns a method of grinding outer surfaces of revolution and a drive carried by the base and movable relative to one another to a position C 'of a pre-formed cylinder formed on a workpiece, an end stop (15). a) intended to axially position a workpiece, a blade (15) for supporting a workpiece carried by the base and placed between the grinding and driving wheels in order to define with these, in said position, an axis (1 6) of a predetermined cylinder circumscribing the   piece (14), the apparatus being characterized in that it comprises   first and second slides (20) fixed relative to each other, placed on the base, near the   first and second opposite faces (17), (18), respectively   surface grinding wheel   of revolution, first and second slides (21)   in relation to each other and mounted on the   each slider carrying a center machining spindle (36) mounted so that its axis of rotation coincides with that of the other spindle and is parallel to the axis of rotation of the grinding wheel, but that he   is radially offset from the axis of said predetermined cylinder   the first and second tools (38) for machining   centering holes arranged facing each other and mounted on the respective center machining spindles, and means (40) for moving the sliders   relative to each other in accordance with a pre-defined cycle   completed operation, while the grinding wheels   fication and training move relative to each other to the other.   2 Machine for machining centering holes in   a part during the execution of a rectification operation   external surfaces of revolution, by means of an eye. centerless grinding machine (10) comprising a   base (11), grinding wheels (12, 13) rotated,   respectively to perform a correction of   external faces of revolution and a drive, suppor-   by the base and movable relative to one another to a position of a predetermined cylinder formed by the workpiece, an end stop (15 a) for axially positioning a workpiece, a blade (15). support of the room   carried by the base and placed between the grinding wheels   training and training, in order to define -with them, in   said position, an axis (16) of a predetermined cylinder cir-   to the workpiece (14), the apparatus being characterized in that it comprises first and second slides (20) fixed relative to one another, placed on the base, close to the first and second faces opposite (17, 18)   of the grinding wheel, the first and second slides   buckets (21) movable relative to each other and mounted on the respective slides, each slide bearing a rotary spindle (36) machining a center, mounted so that its axis of rotation coincides with that of the other spindle and with the axis of said predetermined cylinder, but parallel to the axis of rotation of the grinding wheel, first and second tools (38) for machining centering holes, arranged therein one opposite the other and mounted respectively on the center machining spindles, and means (40) for moving the sliders   relative to each other in accordance with a pre-determined cycle   operation, while the grinding wheels   tion and training move relative to each other the other.   Apparatus for machining centering holes of a workpiece in a centerless grinding machine (10), comprising a base (11), grinding wheels (12, 13) rotated respectively for grinding outer surfaces of revolution and a drive, supported by the base and movable relative to each other to a position of a predetermined cylinder 12. formed by a workpiece, an end stop (15 a) for axially positioning a workpiece, a blade (15) for supporting a workpiece carried by the base and placed between   the grinding wheels and training wheels with which   it defines, in said position, an axis (16) of a predetermined circumscribed cylinder of the workpiece (14), the apparatus   characterized in that it comprises first and second   a sliding block (20) fixed relative to one another, placed on the base, near the first and second opposite faces (17, 18) of the grinding wheel, the first and second movable slides (21). relative to each other, supported by the slideways, each slide having a rotatable spindle (36) machining a center, mounted so that its axis of rotation coincides with that of the other spindle and is parallel to the axis of rotation of the grinding wheel, but offset radially from the axis of said predetermined cylinder of the workpiece, of the first   and second centering hole machining tools (38),   facing each other and mounted on the machining spindles respectively, means (40) for moving the sliders relative to one another in accordance with a predetermined cycle of operation corresponding to the position of the grinding and driving wheels, and a pressure roller (60) for applying radial force to the workpiece to maintain the workpiece against   the grinding wheel after a grinding operation   cation of outer surfaces of revolution has been made.   4 An apparatus for machining centering holes in a centerless grinding machine (10), comprising a base (11), grinding wheels (12), (13)   rotation, intended to perform respectively   grinding surfaces of outer surfaces of revolution and drive, these wheels being supported by the base and movable relative to each other to a position corresponding to a predetermined cylinder formed by a part, the machine also having an end stop (15 a) for axially positioning a workpiece; 13. a one-piece support blade (15) carried by the base and placed between the grinding and driving wheels with which it defines, in said position, an axis (16) of a predetermined circumscribed cylinder (14) to the part, the apparatus being characterized in that it comprises first and second fixed slides (20) one relative to each other, placed on the base, near the first and   second opposing faces (17, 18) of the grinding wheel   first and second movable slides (21) one   relative to each other, mounted on the runners and   each of them having a rotary spindle (36) for machining centers, mounted so that its axis of rotation coincides with that of the other spindle, that it is parallel to the axis of rotation   of the grinding wheel and that it be deported radially   the axis of said predetermined cylinder of the workpiece, first and second tools (38) for machining centering holes arranged opposite each other and mounted respectively on the machining spindles, and means (40) intended   moving the sliders relative to each other,   in a predetermined cycle of operation, while   that the grinding wheels and drive wheels move   relative to each other, a pressure roller (60) being adapted to apply a radial force to a workpiece   in order to tighten it against the grinding wheel   after a surface grinding operation   external revolution has been realized.   A method of machining centering holes in a workpiece, characterized in that it consists in establishing an axis (16) of a circumscribed predetermined cylinder (14) to a workpiece and formed between a drive wheel (13) and a grinding wheel (12) and a blade (15) for supporting workpieces in a centerless grinding machine (10), to place two rotary machining tools (38) for machining centers, the axes of which i and are parallel to the axis of rotation of the grinding wheel, but radially offset from said axis of the predetermined cylinder, to grind an outer surface of revolution on a workpiece with said machine. grinding, and advancing the tools in machining contact with the workpiece, at a predetermined time of the grinding cycle   outer surfaces of revolution.   6 Method of machining centering holes in   a piece, characterized in that it consists in establishing a -   axis (16) of a predetermined cylinder circumscribed to a workpiece (14) and inscribed between a grinding wheel (13), a grinding wheel (12) and a blade (15) for supporting a workpiece on a machine (10) for grinding, without center, to set up two rotary tools (38) for machining centers whose axes coincide with each other and with the axis of said predetermined cylinder of the part, to be realized by grinding an outer surface of revolution on a workpiece using said machine, and advancing the tools in machining contact with the workpiece, at a given instant   predetermined amount of the outer surface grinding cycle revoltuion.   7 A method of machining centering holes in a room, characterized in that it consists in establishing an axis (16) of a predetermined cylinder circumscribed to a part (14) and inscribed between a grinding wheel (13) , a grinding wheel (12) and a blade (15) for supporting a workpiece on a centerless grinding machine (10), to set up two rotary tools (38) for machining centers whose axes   coincide with each other and with the axis of the said predetermined cylinder.   of the room, to correct an external surface of   to move the workpiece on the workpiece, to move the workpiece away from the grinding wheel, to stop the rotation of the drive wheel and workpiece, to apply a   pressure roller (60) against the workpiece, while the rotational   the latter is adopted, and to advance the   tools in machining contact with the workpiece.