Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B31/00—Chucks; Expansion mandrels; Adaptations thereof for remote control
  • B23B31/02—Chucks
  • B23B31/10—Chucks characterised by the retaining or gripping devices or their immediate operating means
  • B23B31/12—Chucks with simultaneously-acting jaws, whether or not also individually adjustable
  • B23B31/1261—Chucks with simultaneously-acting jaws, whether or not also individually adjustable pivotally movable in a radial plane
  • B23B31/1269—Details of the jaws

Definitions

• This invention relates to an internal chuck to be used particularly for cutting external threads on small pipe pieces and of the type where a cylindrical mandrel intend ⁇ ed for insertion in the pipe piece has at least two, pre ⁇ ferably three, axially-running cylindrical sockets placed, in the cylinder surface at uniform angle distance, the depth of said sockets being less than their diameter, but larger than or equal to their radius, and in which cylin ⁇ drical dogs are rotatably embedded having a plane surface parallel to the axis, said surface substantially covering- the same angle ' as ...the openings of the sockets.
• An internal chuck of this kind is known from GB-PS No. 408,777.
• said dogs via a toothed seg ⁇ ment, are activated by a spring to the active position in which the pipe piece is securely held, the dogs being em ⁇ bedded in a fixable body part.
• said internal chuck has some disadvantages, as its action is based on a " certain friction between the dogs and the interior surface of the work piece, so that this friction results in a further rotating of the dogs for gripping the work piece.
• the interior* surface of the pipe piece is smooth there is a danger of reduced friction and the pipe
• the internal chuck according to the invention which is characteristic in that the said mandrel (2) is rotatably connected to a fixable mandrel(l provided with activating members (14) at its end surface (13) facing aforementioned mandrel (2), said members (14) being arranged to make the dogs (9) rotate via mutual ro ⁇ tation of the two parts (1,2).
• the ends of the dogs extend down wards into a housing secured to the mandrel, in which housing the end of the fixable mandrel is rotatably embed ded and fixed axially. This results in the activating members being completely enclosed and protected against outer influence.
• the activating members can be designed so that each of the dogs at its end part ex ⁇ tending into the housing is provided with a radially ex ⁇ tending arm, and that the fixable mandrel at its end sur ⁇ face is provided with a number of pins corresponding to the number of dogs, said pins protruding in between said arms.
• the length of the arms of the. dogs is adapted so that they abut on the • interior wall of the housing when the plane part of the dogs flush with the cylindrical surface of the mandrel.
• the mandrel with the dogs can always be adjusted to neutral position in which the pipe piece freely can be placed on the mandrel or removed therefrom.
• the arms are placed on the dogs in such a manner that the plane part of the dogs flush with the cylindrical surface of the mandrel, when the arms abut on a neighbouring dog or on a part fixed to same.
• the embodiments hitherto mentioned are intended for __ threading in one direction only.
• the end of the dogs protruding into the housing is provided with mainly oval plates, the one end of each of said plates be ⁇ ing secured to the dogs and the other end provided with a hollow in which the pins placed on the fixable mandrel slidingly engage.
• the plates are provided with indentations at the ends facing away from the hollows, a bushing of an elastic, yielding material being placed centrally between the plates and engaging in said indentations.
• FIG.l shows a side view of an internal chuck according to the invention
• FIG.2 shows the internal chuck of FIG.l seen from above
• FIG.3 shows an exploded view of an embodiment of the internal chuck according to the invention
• FIG.4 shows a section of the embodiment of FIG.3 along the line IY - IT of FIG.l in a larger scale
• FIG.5 shows a corresponding section of another embodi ⁇ ment
• FIG.6 shows a corresponding section of a third embodi ⁇ ment.
• the internal chuck consists of mandrels 1 and 2 placed coaxially and conversely rotatable.
• the fixable mandrel 1 is intended for fixing in a thread lathe and is therefore provided with a shoulder 3 serving as a stop device.
• This fixable mandrel 1 is rotatably embedded in a cylindrical housing 5 by an expanded part 4, said housing being secur ⁇ ed to the other mandrel 2 and having an interior annular groove 6 for receiving a resilient locking ring 7 which firmly holds the expanded part 4 of the fixable mandrel 1 in the housing 5-
• the mandrel 2 of the embodiment shown has .three cylin ⁇ drical sockets 8 extending parallel to. the axis of said body, and the depth of which is less than their diameter, so that the sockets 8 are open outwards radially.
• cylindrical dogs 9 In the sockets 8 are placed cylindrical dogs 9 having substantial ly the same diameter as the sockets 8, so that the dogs 9 are rotatable in said sockets 8.
• the dogs 9 have a plane surface 10 parallel to the axis, said surface 10 covering the same angle as the openings of the sockets 8.
• the dogs 9 protrude downwards into the housing 5 where in the embodiment of FIG.3 they are provided with a bottom part 11 from which an arm 12 projects radially.
• Said arm 1 is cylindrical and its axis forms an angle of 30° with the plane surface 10 of the dog 9.
• Three pins 14 are placed at equal angle distance on the end surface 13 of the expanded part 4 of the fixable mandrel 1 close to the circumference of said end surface.
• the pins 14 are provided with annu " arms 12.
• the pins 14 are secured on the end surface 13 of the fixable mandrel 1, and if the two mandrels are rotated conversely to each other the pins 14 will move towards the arms 12 along the arrow 17 ' " by which the arms 12 and the dogs 9 will rotate to the position shown in dotted lines.
• a pipe placed on mandrel 2 and having an interior diameter corresponding to that of said mandrel will be held fast by the edges on the dogs 9, which edges are pressed against the interior wall of the pipe.
• FIG.5 shows a modification of the internal chuck shown in FIG.4 having the same reference numbers for correspond ⁇ ing parts.
• the arms 12 are placed on the bot ⁇ tom part 11 of the dogs substantially diametrically oppo-
• FIG.6 is a schematic view of another embodiment of th internal chuck according to the invention.
• t dogs 9 are provided with a bottom part 21 v/hich has an ov design and v/hich protrudes to a point close to the interi wall of the housing 5.
• At the end facing the housing 5 there are hollows 22 corresponding to the pins 14 leaving a possibility of a slight displacement of said pins in said hollows 22.
• the activated position of the bottom part 21, pin 14 and dog 9 is shown in dotted -lines.
• the bottom parts 21 are adjusted in relation to e ' ach other so that by rotatio they move towards * each other without the pins 14 disengag ⁇ ing the hollows 22.
• the bottom parts 21 ca be provided with an indentation 23 at the end facing the axis of the mandrel, and in this case a bushing 24 of spring steel is placed between the bottom parts, the axial edges of said bushing overlapping each other without inter connection, said bushing engaging the indentations of the bottom parts.
• FIG. .6 can be applied for both righ handed and left-handed threading, while the embodiment of FIG. 4 and FIG.5 only can be applied for threading in one direction, as the arms 12 have to extend on the other sid of pins 14 for threading in the other direction.
• ⁇ - ⁇ RE f OMP In all three embodiments the activating members on-the fixable mandrel 1 are shown as pins 14. However, other forms of activating members could also be imagined, for example, on the fixable mandrel 1 a toothed wheel could " be placed centrally engaging toothed segments on the dogs 9, as sketched in 19 of FIG. 4.
• the " internal chuck can be used for cut ⁇ ting threads on small pipe pieces for producing pipe nipples.
• the internal chuck according to the in ⁇ vention can also be used for other types of work pieces having a cylindrical boring.
• the work piece or the pipe piece is held fast in the present internal chuck in a self- increasing gripping, as in case of threading or other sort of working the two mandrels are turned conversely with a steadily increasing force whereby the activating members are further rotated and press the dogs against the interior wall surface of the work piece.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Jigs For Machine Tools (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8094758

Family Applications (1)

Country Status (3)

Family Cites Families (2)

• 1979
  • 1979-02-09 DK DK54579A patent/DK54579A/da not_active Application Discontinuation
• 1980
  • 1980-02-08 WO PCT/DK1980/000010 patent/WO1980001661A1/en unknown
  • 1980-08-25 EP EP19800900154 patent/EP0023494A1/en not_active Withdrawn

Non-Patent Citations (1)

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