FR2570308A1 - AXIAL TIGHTENING CONNECTION DEVICE BETWEEN A TOOL HOLDER AND A TOOL - Google Patents

Abstract

THE DEVICE IS CHARACTERIZED IN THAT TOOL 11 INCLUDES AN ANNEX PART 28, MADE BY FORMING FOLLOWING THE CENTERING TENON 27, WHICH IS SUBDIVIDED BY A TRANSVERSE SLOT OPEN TOWARDS ITS END SURFACE 29 IN TWO CLAMPING FINGERS 32 , 33 SYMMETRICAL WITH RESPECT TO THE LONGITUDINAL AXIS 18 OF THE TOOL, THE TOOL HOLDER 12 INCLUDES, FOR THE APPENDIX PART 28, A CAVITY 53 FOLLOWING THE BALLING 52 AND PRESENTING THE SAME AXIS AND A MAINTENANCE SCREW 78 WITH A LENGTH EXCEEDING THE DIAMETER OF PART 28 AND, EXCEEDING THIS PART 28 IN THE RADIAL DIRECTION TO BE MAINTAINED IN THE DIRECTION OF THE LONGITUDINAL AXIS 18 OF THE TOOL INSIDE A RADIAL BORE 56 THROUGH THE DOOR- TOOL 12 IN THE FREE CELLAR ZONE 53.

Description

The present invention relates to a clamping connection device

  axial between a tool holder and a tool such as a milling cutter, a reamer and, in particular, a solid drill, the tool holder having a central cylindrical bore whose axis coincides with the longitudinal axis of

  the tool and which has an annular surface perpendicular to

  across the longitudinal axis of the tool and facing

  the tool and the tool comprising an annular contact surface

  area that can be pushed against the annular surface of the

  tool holder and a centering pin which starts from this over-

  face, whose axis coincides with the longitudinal axis of the

  til and which engages exactly in the central bore, the device further comprising, in the area of the insertion parts of the tool and the tool holder,

  clamping, including a retaining screw which can be controlled

  operated from the outside and is oriented in the radial direction, clamping elements which bear, on the one hand, on the tool holder and, on the other hand, on the tool and transform a radial force exerted by the screw holding in an axial clamping force pushing the contact surface of

  the tool against the annular contact surface of the holder

  tool. A clamping connection device of this type is described for example by patent DE-PS 31 08 439. As, on the one hand, the housings for tools formed in the spindles of drills and milling machines have very

  varied, and that it exists next to pre-

  feeling the most varied angles at the apex also special shapes and as, on the other hand, we must be able to use different types of tools, such as milling cutters, reamers, and drills full of different sizes under such varied conditions as possible, it is customary to make the tools in the manner of a set of

  construction. We can then, for specific operations

  born, associate the desired tool head each time with a

  tool holder for housing the tool in question.

  You can also modify the length by inserting

  longer connecting pieces or long moans.

  In the known embodiment, a radial bore of the insertion stud contains a connecting bolt which can move therein in the radial direction and has, at its two

  ends, a conical tip or a conical recess.

  In the tool holder, two diametrically opposite retaining screws are held in orientation threads

  radial and have, at their end surfaces

  mite looking inward, corresponding recesses or conical tips. The common axis of the two retaining screws is slightly offset in the axial direction by

  relative to the axis of symmetry of the orienting bolt

  radially, so that when tightening the hand screws

  tien, the conical tips penetrate with a slight offset in the conical recesses and that, due to this action similar to that of a wedge, the radial force exerted by the retaining screws is transformed into an axial clamping force. Since the connecting bolt can move freely in the radial direction, it is obvious that the insertion pin does not undergo a radial force in the insertion bore of the tool holder, which guarantees that

  the annular surface of the tool holder and the contact surface

  tool tact apply completely and under strong pressure against each other and achieve excellent

friction bonding.

  However, in this device, the transmission of forces is not carried out in a favorable manner, because,

  on the one hand, the clamping force of the tool holder is transmitted

  through the retaining bolts on the connecting bolt and from this to the tenon of the tool. This means that the forces are transmitted by several

  elements which are weak points of the construction.

  One of these weak points is the housing of the retaining screws in the tool holder, because the sides of the threads

  engaged on each other only build support

  with contact lines which depend only on chance,

  because no thread absolutely covers its entire surface.

  Another weak point is formed by the contact zone, which is in the most favorable case only a linear contact, between the conical end pieces and the corresponding conical recesses offset relative to the axis. Indeed, if the angles of the cones are exactly the same, this is the most favorable case, in which the contact zone is reduced to a line, that is to say, as a result of Hertz compression, it is only deformed on one

  very narrow surface. This easily results in over-

  load and, consequently, deflection, which limits the safety of the clamping connection, in particular in the case of a tool subjected to vibrations with spikes

  alternating load. It can also result in pheno-

  wear patterns leading to premature decommissioning

device.

  In addition, for the connection to be strong enough, the two retaining screws must be strong enough

  which, in some cases, can lead to dete

  improvement of their thread or of the thread of the threaded bore of the tool holder. Because, when the tightening of the retaining screw is intensified, the latter, as a result of the wedge action, in reaction to the clamping force, is

  pushed more and more obliquely against the area of the ta-

  line located in front of it and that due to the random

  roof and linear contact lines, it penetrates into the sides of the thread, a large part of the torque required for tightening is absorbed therein, so that a sufficient axial clamping force can only be exerted when the device is new. Another

  disadvantage is that for a change of

  til, you must unscrew the two retaining screws each time

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  diametrically opposite until they release the

  radial sage of the insertion post. This results in a mani-

  complicated pulation. Finally, another drawback consists in that the connecting bolt must penetrate into the radial bore of the insertion stud with as little play as possible, otherwise the transmission of the forces of this bolt

  at the bore wall would also be done by

  linear tact. As a result, the connecting bolt has only freedom of movement with respect to the insertion stud

  in one dimension, which means that the tarau-

  tool holder holes and the radial bore of the insert post

  tion must, seen in the longitudinal direction of the axis of the tool, exactly coincide, otherwise the contact zone between the conical elements not only is no longer in the median plane, but is offset laterally, which has the effect the insertion post is again pulled obliquely into the insertion bore. This shift

  of the force transmission plan occurs naturally-

  ment when, for example, the conical recess of one of the retaining screws is offset eccentrically. The known embodiment therefore requires a manufacture of a

  great precision if you want to achieve the desired effect.

  The object of the invention is to produce a connection device with axial clamping of the type initially defined in which the connection between the tool holder and the tool is not subjected to any unilateral load, this result being able to be obtained without complications of manufacture and for a long period of use, so as to ensure, by better tightening between the annular surface of the tool holder and the contact surface of the tool, and even after repeated use of the connection device, safe and solid bond. Handling should also be easier. This object is achieved, according to the invention, due to the fact that the tool comprises an annex part, following the tenon

  centering, which is subdivided by a transverse groove

  dirty open towards its end surface, in two symmetrical clamping fingers with respect to the longitudinal axis of the tool, that the tool holder comprises, for the annexed part in question, a free cavity which follows the central bore and that the retaining screw has a length exceeding the diameter of the annex part and, by its two ends projecting beyond this part in the radial direction, is

  held in the direction of the tool axis inside

  of a radial bore passing through the tool holder in the

free cavity area.

  Various other features of the invention res-

  emerge from the detailed description which follows.

  An embodiment of the object of the invention is shown, by way of nonlimiting example, in the accompanying drawing.

  Figure 1 is a top view of a device

  the invention while the tool and the tool holder are

separated.

  Figure 2 is a side view along arrow 2

  of the device shown in Figure 1.

  FIG. 3 is an enlarged view of the device.

positive in clamping position.

  Figure 4 is a front view of the tool holder, more

  large scale, in the direction of arrow 4 in FIG. 1.

  FIG. 5 is a rear view of the tool, on a larger scale, in the direction of the arrow 5 in FIG. 1,

  the retaining screw and a clamping cylinder being equally

ment represented.

  Figure 6 is a view of the clamping cylinder in the

  direction of arrow 6 in FIG. 5.

  In FIG. 1, the reference ll designates a tool, more specifically a solid drill, which is placed so as to be able to be mounted in a tool holder 12 which, at its

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  tower, is maintained by its corner pin 13 in a box-

  tool 14 which is only indicated in broken lines.

  This tool housing 14 can be a fixed or rotary lining or the housing of the revolver head of a machining center. Reference 16 designates a length scale

  which, for comparison purposes, gives the length of 10 cm.

  The tool represented there is of a type known in its zone starting from the bead 17 and extending to the left in

  the direction of the tool axis and carries, at its sur-

  end faces, an outer cutting plate 19 and a

  inner cutting plate 21. Behind the cutting plates

  your lead out from conduits 22 and 23 in which a coolant circulates and which lead to the right

to a common axial duct 24.

  The bead 17 has, on its right side, a bearing surface 26 and, starting from this surface and having the same axis as the longitudinal axis 18 of the tool, a centering pin 27. This pin is extended by an annex part 28. FIG. 2 shows that this part 28 is subdivided, by a transverse groove 31 open on the side of the end surface 29, into two clamping fingers 32 and 33 symmetrical with respect to the longitudinal axis 18 of the tool. With respect to a plane of symmetry which corresponds to the plane of the sheet of FIG. 2 and which, in FIG. 4, is designated by the reference 34, the clamping fingers 32 and 33 comprise, produced by forming, oblique surfaces 36 , 37, 38 and 39 diametrically opposite and moving apart towards the end surface 29. In FIG. 1, the first end surfaces 36 and 37 and 38 and 39 are aligned in pairs one behind the other and FIG. 2 shows that the aligned oblique surfaces, for example the surfaces 38 and 39, form flat surfaces situated in a common oblique plane. First oblique surfaces leave short free surfaces 41, 42, 43 and 44 parallel to each other which are

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  extend by pairs of third surfaces 46, 47, 48 and 49 which move apart towards the centering pin 27. In FIG. 1, these surfaces are also aligned

  in pairs and form planar surfaces in a plane

  mun. These shapes are very easily achievable by means of an angular cutter moved in the radial direction on the clamping device. It goes without saying that free surfaces

  41 to 44 may also have the form of connecting arcs

  is lying. It is advantageous that the first oblique surfaces 36 to 39 form with the third oblique surfaces 46 to 49 an angle of about 90 and are inclined at 450 on

the plane of symmetry 34.

  The tool holder 12 has an annular surface 51 facing the tool and a central bore 52 which is coaxial with the longitudinal axis 18 of the tool and in which the centering pin 27 engages. The central bore 52 is extended by a free cavity 53, also cylindrical, which offers

  free space for the annex part 28. Figure 1 shows

  also feels a conduit 54 for a coolant which goes to the right and, crossing a bore indicated in broken lines in Figure 3, leads to a not shown fitting formed at the housing of

  the tool. The tool holder 12 is, as shown in the figures

  gures 1, 3 and 3, traversed right through, at the free position 53, by a radial bore 56. This bore

  radial 56 is oriented perpendicular to the plane of symmetry

  sorts 34 and, therefore, parallel to the transverse groove

  versal 31. The radial bore contains, on each side of the

  plane of symmetry 34, a clamping cylinder 57 and 58 for

  before moving in the radial direction and the ends

  facing inwards have, as shown in the fig-

  res 3, 5 and 6, the shape of second surfaces 59 or 61 and

  62 corresponding to the first oblique surfaces.

  FIGS. 5 and 6 show that the oblique surfaces aligned one behind the other in the direction of the plane of symmetry 34, for example the two oblique surfaces 61 and 62, form flat surfaces situated in a common oblique plane. This flat surface is then also

  inclined by 45 on the longitudinal axis 18 of the tool.

  For reasons of symmetry and stability, the clamping cylinders 57 and 58 also include fourth

  oblique surfaces 63 or 64 and 66 corresponding to the third-

  my oblique surfaces 46 to 49, so that the clamping cylinders are symmetrical with respect to a first plane

  radial 67 parallel to the annular surface 51.

  As shown in particular in Figure 4, the cylinders

  clamp 57 and 58 have, at their periphery, a

  flat 68 which does not extend to the opposite end surfaces

  69 or 71, so that this flat part has the character of a groove limited on both sides in the radial direction. As shown in Figure 4, the area of the flat parts of the two clamping cylinders has a safety bolt 72 or 73 which protrudes inwards in the radial direction out of the radial bore 56, preferably in the form of 'a threaded bolt which is screwed into a corresponding thread 74. This safety bolt 72, 73 prevents the corresponding tightening cylinder 57, 58 from turning and

  to be pulled too far out of the radial bore 56.

  As shown in Figure 4, the clamping cylinders 57 and 58 have threads 76 and 77 which are in the extension of one another and have equal pitches, but

of opposite meanings.

  A retaining screw 78, in the form of a differential screw, which is shown separately in FIG. 5, therefore comprises, at its two ends, external threads 79 and 81 having opposite pitch directions. The middle part 82, which does not carry a thread, has a reduced diameter as in the case of the usual clamping screws and is lower

  from approximately 2 to 3 mm at the free width of the transverse groove

  versal 31 of appendix 28 (Figure 2), which makes

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  that the gap which remains, after assembly, between the middle part and the clamping fingers 32 and 33 is sufficient

  large so as not to impede the flow of coolant.

  Clamping screws with a thin middle part are items that are commonly found in the trade and we know

  that they can withstand considerable tensile forces

  rables. The two ends of the retaining screw 78 comprise

  try hexagonal recesses 83 and 84, so that the retaining screw can be operated on both sides using a suitable tool. This arrangement has the advantage that, regardless of the position of rotation in which the tool holder 12 is located, there is always a recess

  hexagonal accessible. Two or more

  tils at a time to loosen, if necessary, a

holding too tight.

  Figure 1 shows the tool holder 12 in the state where there is no clamping, that is to say that, due to the action of the retaining screw 78, the clamping cylinders

  57 and 58 are moved far enough to the former

  interior so that the interior frontal surfaces 71 are at a sufficient distance from each other so that the enlarged part 28 in the shape of a hammer can

  pass between them. In this position, it is therefore possible

  ble to engage the tool 11 in the tool holder 12, obviously making sure that the tool ll takes a position of

  rotation such that the middle part 82 of the hand screw

  Yours 78 can penetrate into the transverse groove 31 of the annexed part 28. As shown in particular by the

  figure 2, this result is guaranteed by a dowel

  position 87 which is held in a bore 86 formed along a parallel axis in the annular surface 51 of the tool holder 12 and which can sink into one of the corresponding positioning bores 88 and 89 distant from one another by 1800, which are spared in the surface of

contact 26 of tool 11.

  When a tool il, with its annex part 28 and its centering pin 27, is inserted far enough into

  the central bore 52 and in the cavity 53 so that the over-

  contact face 26 is applied against the annular surface 51, the retaining screw 78 is turned by one or other of its ends, as desired, so that, because the

  threads are in opposite directions, the two clamping cylinders

  ge 57 and 58 move towards each other. During this movement, the second oblique surfaces of the cylinders meet the first oblique surfaces of the clamping fingers (these second oblique surfaces 59 and 61 and the first oblique surfaces 38 and 36 are indicated in FIG. 3), so that, by following the wedge action of the oblique surfaces which slide one on the other, the

  clamping fingers are pulled in the axial direction. The cylin-

  clamping dres 57 and 58 have freedom of movement the

  along the radial bore 56, that is to say perpendicular-

  ment to the plane of symmetry 34 and the oblique surfaces which slide one on the other offer, owing to their planar shape, freedom of movement between the clamping fingers and the clamping cylinders in the direction of the plane of symmetry so that , even in case of offset of the median axis of the radial bore 56, it is ensured that the annex part 28 is pulled exclusively by a clamping force oriented in the axial direction. The contact surface 26 is therefore exactly pushed against the annular surface 51. The forces are transmitted from the clamping fingers through the clamping cylinders and their smooth outer wall to the inner surface, also cylindrical, of the radial bore 56, so that between the two parts which must be tightened one

  against the other, i.e. between the tool and the holder

  tool there is intercalation of only one intermediate piece

  movable diary, which is a clamping cylinder. As the forces are transmitted by smooth surfaces, we avoid

  drawbacks inherent in linear compression and over-

  all there is no thread on the path of the force of

  Tightening. The retaining screw 78 is stressed exclusively-

  ment in tension while the overturning moments in the clamping cylinders are absorbed by the guidance of the clamping cylinders in the radial bore 56 which is carried out in an excellent manner. Under these conditions, there is also no disturbing blocking forces in the area during the operation of the retaining screw.

  between the external thread and the internal thread.

  The centering is ensured by elements which are separated, in space, from the elements designed to ensure the clamping in the axial direction, so that their realization can be carried out having exclusively in view the function

  assigned to them. This is how, for example,

  central sage 52 has a wall surface which is not

  interrupted by no radial bore, which offers the best

  their conditions for making a piece of dimensions

very precise.

  FIG. 3 shows that the clamping fingers, in the sector corresponding to the first and third oblique surfaces, are symmetrical with respect to a second radial plane 91 parallel to the contact surface 26, the two planes 67 and 91 oriented in the radial direction being, in the state of connection shown, slightly offset from each other in the axial direction, so that it is certain that only the first oblique surfaces come into contact with the corresponding second oblique surfaces . If, as in the example embodiment shown,

  the positioning pin 87 is fixed in the holder

  tool 12, this results in the advantage that the use of

  tion of these pegs because, of course, the number of

  tool holder is much less than the number of tools.

  The fact that the positioning pin 87 corresponds in the tool 11 to two positioning bores 88 and 89 distant from one another by 180 has advantages

  for use in machining installations

  both what is called a revolver head. As my-

  already in FIG. 2, the tool holder 12 is, because of its wedge pin, linked to a determined mounting position

  which is naturally found in the housing of the tool.

  However, it can naturally happen that the housing of the

  it is not the same in all machines, but results in giving the tool holder positions different from 180. However, when you use a solid drill, you tend

  place the outer cutting edge 19 (Figure 1) horizontal-

  ment (if the tool must be kept stationary), because this arrangement ensures better chip evacuation and, ultimately, this external cutting edge must be as much

  as possible on the side of the operator who, in this posi-

  tion, sees the bore better. So from

  because the tool, due to the presence of the two bores

  opposite positioning ges 88 and 89, can be engaged

  in the tool holder 12 optionally in two remote positions

  your from one another from 180 it is possible to fill

  the previous condition whatever the fixing system

  tion of the tool holder 12 in the tool housing.

  Regarding the contact surface 26 and the surface

  annular face 51 applied one against the other, it has proved advantageous to provide at least one of these surfaces with what is called a hollow polishing of the order of 3 to 4) m, so that this surface, in the state where there is no tightening, appears slightly conical. However, when there is clamping, the two surfaces are pushed one

on the other over their entire surface.

Claims (9)

CLAIMS i - Connection device with axial clamping between a tool holder and a tool such as a milling cutter, reamer and, in particular, a solid drill, the tool holder comprising a central cylindrical bore whose axis coincides with the axis longitudinal of the tool and which has an annular surface perpendicular to the longitudinal axis of the tool and facing the tool and the tool having an annular contact surface which can be pushed against the annular surface of the holder -tool and a centering tenon which starts from this surface, the axis of which coincides with the longitudinal axis of the tool and which engages exactly in the central bore, the device further comprising in the area of the insert parts of the tool and the tool holder, of the clamping elements, comprising a retaining screw which can be operated from the outside and is oriented in the radial direction, which bear on the one hand , on the tool holder and, on the other hand, on the tool and transform a force radial exerted by the retaining screw in an axial clamping force pushing the contact surface of the tool against the annular contact surface of the tool holder, characterized in that the tool (11) has an annex part (28) , produced by forming following the centering pin (27), which is subdivided by a transverse groove (31) open towards its end surface (29) into two clamping fingers (32, 33) symmetrical with respect to to the longitudinal axis (18) of the tool, in that the tool holder (12) comprises, for the annex part (28) a free cavity (53) which follows the central bore (52) and has the same axis as it and in that the retaining screw (78) has a length exceeding the diameter of the annex part (28) and, by its two ends projecting this part (28) in the radial direction, is maintained in the direction of the longitudinal axis (18) of the tool inside a radial bore (56) passing through the tool holder (12) in the region of the free cavity (53) .   2 - Connection device with axial clamping according to claim 1, characterized in that the clamping fingers (32, 33) comprise, produced by forming,   first oblique surfaces (36, 37, 38, 39) which are di-   metrically opposite with respect to a plane of symmetry (34)   oriented perpendicular to the plane of the transverse groove   dirty (31) and move away towards the front surface   (29) terminal, in that the radial bore (56) of the holder   tool (12) is oriented perpendicular to the plane of symmetry   sorts (34), in that, in the radial bore (56), each   that c6té of the plane of symmetry (34) already mentioned, there is a clamping cylinder (57, 58) which can move there in the radial direction and which comprises, on its front surfaces (71) turned towards the first surfaces oblique (36, 37, 38, 39), second oblique surfaces (59, 61, 62) which correspond to them and in that the retaining screw (78) is supported in the two clamping cylinders (57, 58) in the   radial direction with respect to the longitudinal axis (18) of the tool.   3 - Connection device with axial clamping according to claim 2, characterized in that the retaining screw (78) is a differential screw and that the clamping cylinders (57, 58) have threaded bores (76, 77) which have the same axis and are equal steps, but of opposite directions. 4 - Connection device with axial clamping according to claim 3, characterized in that the two ends of the retaining screw (78) have a hexagonal recess   (83, 84) and are accessible from the outside.   - Connection device with axial clamping according to   claim 2, characterized in that the gripping fingers   rage (32, 33) comprise, formed by forming, short free surfaces (41, 42, 43, 44) parallel to each other   others, diametrically opposite with respect to the plane of symmetry   sorts (34) and starting from the first oblique surfaces and from the third oblique surfaces (46, 47, 48, 49) starting from the free surfaces and deviating towards the tenon centering (27).   6 - Connection device with axial clamping according to claim 5, characterized in that at the front surfaces of the clamping cylinders (57, 58) there are also   ment of the fourth oblique surfaces (63, 64, 66) corresponding   laying on the third oblique surfaces (46 to 49), so that the clamping cylinders (57, 58) are symmetrical with respect to a first radial plane (67) parallel to the annular surface (51) and that the clamping fingers ( 32, 33),   in the area corresponding to the first and third sur-   oblique faces, are symmetrical with respect to a second radial plane (91) parallel to the contact surface (26),   the first and second radial planes (67, 91) being, when   that the connection is ensured, slightly offset in the direction axial with respect to each other.   7 - Connection device with axial clamping according to   one of claims 1 to 6, characterized in that,   seen in the direction of the plane of symmetry (34), the pre-   first oblique surfaces (36, 37, 38, 39) of the gripping fingers   consecutive rages (32, 33) are in pairs in alignment with each other and that the aligned oblique surfaces (36/37, 38/39) form planar surfaces located in a common oblique plane.   8 - Connection device with axial clamping according to the   claim 7, characterized in that the second surfaces   these obliques (59, 61, 62) of each clamping cylinder (57, 58) form flat surfaces located in a plane common oblique.   9 - Connection device with axial clamping according to   one of claims 7 or 8, characterized in that the   oblique plane of flat surfaces is inclined at 45 on the axis longitudinal of the tool (18).   - Connection device with axial clamping according to   one of claims 2 and 3, characterized in that the 27 0308'l 16,273   clamping cylinders (57, 58) have, at their periphery   rie, a flat part (68) - which does not go to the opposite frontal surfaces (69, 71) and in that, in the radial bore (56) 4 of the tool holder (12), in the area of the parts planes (68) of the two clamping cylinders, there are   safety bolts (72, 73) protruding inward.   ll - connection device with axial clamping according to claim 3, characterized in that the retaining screw (78) forms, between its threaded end portions (79, 81),   a middle part (82) of smaller diameter and without thread.   12 - Connection device with axial clamping according to claim 11, characterized in that the diameter of the middle part (82) is at least 2 to 3 mm less than the free width of the transverse groove (31) of the annex (28).   13 - Connection device with axial clamping, in particular   ment according to one of claims 1 to 12, characterized   in that a positioning pin (87) projecting and parallel to the axis is engaged in the annular surface   (51) of the tool holder (12) and in that the position bores   tction (88, 89) corresponding distant from each other by 180 are formed in the contact surface (26) of the tool (11).   14 - Connection device with axial clamping according to the   claim 13, characterized in that the pin of po-   positioning (87) and the positioning bores (88,   89) are in the plane of symmetry (34).