Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D53/00—Making other particular articles
  • B21D53/10—Making other particular articles parts of bearings; sleeves; valve seats or the like
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D51/00—Making hollow objects
  • B21D51/02—Making hollow objects characterised by the structure of the objects
  • B21D51/10—Making hollow objects characterised by the structure of the objects conically or cylindrically shaped objects

Definitions

• the invention relates to a method for the round bending of bushings, in which a blank is inserted into a gap between a core and a first die, which has a first molding chamber, the inner contour of which is at least approximately complementary to the outer contour of the bushing and extends over at least half the bushing circumference extends that by relatively moving the core into the first mold chamber, the blank is bent approximately in a preform, that by relatively moving the core immersed in the first mold chamber into a second mold chamber of a second die, the two legs of the U-shape are bent Board are deformed into a socket in a final shaping and that the edges of the two molding chambers of the two molding dies open into parallel end face planes of the molding die and these end face planes at least approximate one another in the closed position of both molding chambers.
• a method of this kind is known. Most round housings, bushings and bearing shells are bent from pre-punched blanks according to this principle, but the result after the final shaping is unsatisfactory, in particular because the roundings are imperfect in the area of the end face planes. Irregularities also occur at the socket ends. Reworking by calibrating the bushes is usually necessary. With the known methods, grinding marks on the sleeve surfaces cannot be avoided and high-quality materials with, for example, multilayer layers, plastic-coated boards and the like cannot be processed by this method without surface damage.
• the object of the invention is to provide a method and an apparatus for carrying it out, with which or with the blanks can be bent more precisely than before and this bending takes place more gently, so that even sensitive materials can be processed.
• round bending refers to the bending of rotationally symmetrical objects, such as cylindrical or conical bushings, but is not restricted to this.
• the bent parts can also have oval, elliptical, teardrop-shaped and similar cross sections.
• the object is achieved in a method according to the invention of the type mentioned at the outset in that the core is moved deeper into the first molding chamber than it corresponds to the sleeve radius, so that the sleeve axis after the preforming lies at a distance from the die face plane within the first molding chamber.
• a further development of the invention consists in that the core is also moved deeper into the second mold chamber than it corresponds to the socket radius, so that after the socket has been finally shaped, the socket axis lies within the mold chamber at a distance from the end face plane of the second die.
• the socket Since the middle of the socket is preferably run over by both end dies from their end planes, the socket is rounded much better in the 90 "and 270" regions than in the known bending process, in which the dies always move exactly to the middle of the socket.
• at least the core, but preferably also the first die, between the preforming and the final shaping must have a cross section be changed.
• the device according to the invention offers a solution for this, which will be discussed below.
• Another important embodiment of the invention is that an auxiliary molding takes place between preforming and final shaping, by means of which only the ends of the U-legs of the board are bent by relative retraction of the core into the second molding chamber in accordance with its curvature, without the between these ends and to bend the U-leg parts lying in the preformed base of the U-shaped blank.
• the blank is thus transformed into an elongated round profile, which in particular favors the precise rounding of the bush ends.
• a further embodiment of the invention consists in that the machining of the bushing takes place in two working planes, the preforming, the auxiliary shaping and the final shaping being assigned to the first working plane and the bushing after the final shaping is pushed axially into the second working plane and calibrated there.
• An important feature of the method in the invention is that before the start of the preforming, the core is given a larger overall cross section by axially retracting an auxiliary core, so that the bushing center can be passed over by at least one of the form punches.
• This auxiliary core is now used very advantageously according to the invention to push the socket after its final shaping into the second working plane on an expansion sleeve of the calibration station.
• the invention further relates to a bending device for carrying out the bending process and this device is characterized in that the core and the first molding chamber have a larger cross-section during the pre-molding process than during the final molding process. This feature can be achieved by exchanging the cores.
• a more advantageous alternative is the use of an auxiliary core, which is temporarily removed for the final shaping.
• This auxiliary core preferably sits on the core with a concave surface and has a convex working surface which is complementary to the inner surface of the molding chamber.
• This auxiliary core thus has a crescent-shaped cross section, in which the working surface and the inner surface lie on circular cylinders of the same size.
• the first die preferably supports a slide which is displaceable in the direction of the bushing and which forms part of the first molding chamber, and on this slide the end face of the molding chamber is formed, which defines the parting plane of the die, during preforming and intermediate or auxiliary molding.
• This division plane is then at a distance from the center of the bush on the side of the first die.
• the auxiliary core can now be connected to the slide to form a jointly displaceable structural unit, so that after this structural unit has been removed from the first working level, the core and the first molding chamber for the final shaping of the bushing receive new cross-sectional shapes, so that the unchanged second shaping die receives the center of the bushing can run over for the final shaping of the socket.
• the method according to the invention allows the boards to be connected to the carrier strip via two webs which are assigned to the end regions of the board.
• the board can therefore be positioned more precisely in the bending device. Since these webs after separation from Carrier strips leave end-side shear marks on the socket, the sockets produced according to the invention differ from the prior art in that these shear marks are located in the quarters adjacent to the socket gap.
• the three-step bending process by changing the core and mold chamber cross-sections ultimately leads to a gentle and very precise round bending of blanks, so that the method according to the invention is also suitable for highly sensitive layered board materials.
• the two mold stamps of the device according to the invention have a width at least equal to twice the width of the bushing to be bent and each have a calibration chamber axially next to their mold chambers, with both calibration chambers having the same mirror image, the curvature of which corresponds to that of the associated mold chambers, but are identical only extend over a circumferential angle of 180 °.
• the two calibration chambers form a circumferentially closed calibration cavity corresponding to the outer surface of the socket.
• a spreading device which preferably consists of an expansion sleeve, which can be widened or narrowed by an internal cone by axially displacing an actuating rod.
• FIG. 1 - FIG. 6 The bending device with the plate to be bent in successive work processes
• FIG. 7 - FIG. 12 cross-sections through the bending device, in the work processes assigned to the respective views.
• the auxiliary core 18 and the slide 20 form a structural unit which is pushed back and forth in the direction of arrow A (FIG. 10) by an actuating tool, not shown.
• the first molding die 12 has a molding chamber 22 with a semi-cylindrical bottom in the form of a cylinder section. In the area of the slide 20, the part-cylindrical inner surface of the molding chamber 22 continues continuously into a semi-cylindrical surface and opens out with parallel inner surface sections at the end face plane 23 of the first molding die 12.
• the second molding die 1 4 consists of two die halves 1 4a and 1 4b, which together form a second molding chamber 24. This is approximately mirror-inverted to the molding chamber 22 and, apart from a step between the two stamp parts 14a and 14b, has a semi-cylindrical contour, to which parallel inner surface sections pointing downward adjoin.
• the stamp part 1 4b is vertically displaceably mounted on the stamp part 14a and is biased by means of a spring 1 5, which is illustrated only schematically here, against a stop of the stamp part 1 4a in such a way that a step 17 is formed in the mold chamber 24 in its central plane.
• the two form stamps 12, 14 have moved apart.
• the core 16 is stationary.
• a board 26 is inserted into the gap between the core 1 6 and the end face of the first die 1 2.
• the form stamp 12 then moves upwards in the direction of the arrow according to FIG. 1 and bends the board 26 into a U shape as shown in FIG. 2 is shown.
• the core center which corresponds to the center of the bushing, lies below the end face 23 of the first die 1 2.
• the core 1 6 has thus entered the molding chamber 22 deeper than it corresponds to the bushing radius.
• the 90 ° and 270 ° positions of the socket to be formed are thus in the molding chamber 22, so that the U-legs of the plate 26 formed do not spring outwards, but lie closely against the auxiliary core 18.
• the preforming process of the board 26 is thus ended.
• the second die 1 4 moves according to FIG. 3 down.
• the ends 26 'of the U-legs of the blank blank are bent inwards when they come into contact with the mold chamber wall 24 and lie on the auxiliary stamp 18 when the mold stamp 14 is placed on it.
• the straightness of the U-legs of the blank 26 is preserved. Due to the stage 17 in the molding chamber 24, the bending of the two leg ends 26 'takes place with a slight time offset.
• the bending of the two leg ends 26 'between the second die 14 and the auxiliary core 18 represents an intermediate auxiliary shaping, according to which these leg ends 26' are bent exactly in a circular cylindrical manner and thus already have their final shape.
• the auxiliary core 1 8 is pulled together with the slide 20 in the direction of arrow A (FIG. 10) axially between the shaping dies 1 2, 14, for which purpose the second shaping punch 1 4 is possibly lifted somewhat.
• the second die 1 4 moves downward again to bring about the final shaping of the bushing 27.
• the die 1 4 can extend deeper beyond the end face 23 of the first die 1 1 to the bottom surface 28 of the die 1 2, the end face 1 9 of the second die 1 4
• the core center travels downward until the inner surface of the molding chamber 24 likewise deforms the socket blank at its straight U-leg sections in a circular-cylindrical manner, thus completing the final shaping of the socket 27.
• the socket ends are usually interlocked.
• the bush edges have mutually engaging projections and recesses. Since the stamp half 1 4b first presses one socket edge against the core 16, the form-fitting closing of the socket 27 can take place during the last phase of the downward movement of the stamp part 14a. Both stamps 1 2 and 14 then move apart (FIG. 5), so that the finished bushing 27 can be stripped from the core 1 6.
• Figures 7 to 1 2 illustrate an additional calibration process of the bushing 27, which takes place in the same device 10 on a second working level.
• tool parts 30, 32 are attached to the two mold punches 1 2, 1 4 on the right, each having calibration chambers 34, 36, which have the same curvatures as the mold chambers 22, 24, but each only extend over a circumferential angle of 180 °.
• the division plane of the calibration chambers 34, 36 thus lies at the core center.
• the hollow core 1 6 is penetrated by an operating rod 38 which carries a cone 40 in the second working plane, which is surrounded by an expansion sleeve 42.
• the structural unit consisting of auxiliary core 1 8 and slide 20 is now pushed back into the first working level after final shaping of the bushing 27, whereby the auxiliary core 18 inserts the bushing 27 on the core 16 into the second working level via the expansion sleeve 42 pushes.
• the socket 27 calibrated there in the previous work cycle is simultaneously pushed out of the device 10 (FIG. 12).
• the device 10 is then prepared in the first working level for receiving a new board 26.
• the work processes of preforming, intermediate shaping and final shaping of the bushing 27 are repeated and in the position according to FIGS. 4 and 10 the two tools 30, 32 are closed and form a cylindrical calibration cavity which encloses the bushing 27.
• the actuating rod 38 is pulled in the direction of the arrow A (FIG. 10), as a result of which the expansion sleeve 42 is expanded by the action of the cone 40 and the bushing 27 is calibrated.
• a board 26 is thus bent and closed with high precision in a first working level without any handling devices and calibrated in the second working level.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Bending Of Plates, Rods, And Pipes (AREA)
• Shaping Of Tube Ends By Bending Or Straightening (AREA)
• Forging (AREA)
• Containers Having Bodies Formed In One Piece (AREA)
• Closures For Containers (AREA)
• Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

Family

ID=7757805

Family Applications (1)

Country Status (10)

Cited By (2)

Families Citing this family (17)

Citations (3)

Family Cites Families (7)

• 1995
  • 1995-03-25 DE DE19511095A patent/DE19511095A1/de not_active Withdrawn
  • 1995-07-07 DE DE29511070U patent/DE29511070U1/de not_active Expired - Lifetime
• 1996
  • 1996-03-19 AT AT96908069T patent/ATE185502T1/de not_active IP Right Cessation
  • 1996-03-19 CN CN961902299A patent/CN1064869C/zh not_active Expired - Fee Related
  • 1996-03-19 DE DE59603336T patent/DE59603336D1/de not_active Expired - Fee Related
  • 1996-03-19 KR KR1019960706661A patent/KR970703207A/ko not_active Application Discontinuation
  • 1996-03-19 RU RU96124365/02A patent/RU2161544C2/ru not_active IP Right Cessation
  • 1996-03-19 EP EP96908069A patent/EP0759822B1/de not_active Expired - Lifetime
  • 1996-03-19 ES ES96908069T patent/ES2138810T3/es not_active Expired - Lifetime
  • 1996-03-19 CA CA002220097A patent/CA2220097A1/en not_active Abandoned
  • 1996-03-19 JP JP8528874A patent/JPH10501467A/ja not_active Ceased
  • 1996-03-19 WO PCT/EP1996/001172 patent/WO1996030139A1/de active IP Right Grant

Patent Citations (3)

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