Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F5/08—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of toothed articles, e.g. gear wheels; of cam discs
  • B22F5/085—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of toothed articles, e.g. gear wheels; of cam discs with helical contours
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F5/08—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of toothed articles, e.g. gear wheels; of cam discs
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
  • B30B11/005—Control arrangements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
  • B30B11/02—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a ram exerting pressure on the material in a moulding space
  • B30B11/04—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a ram exerting pressure on the material in a moulding space co-operating with a fixed mould
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

Definitions

• the invention relates to a device for the production of compacts with zylindför ige Hauptformieri ⁇ and helical Nebe ⁇ formeleme ⁇ ten according to the preamble of claim 1.
• a device for the production of compacts with zylindför ige Hauptformieri ⁇ and helical Nebe ⁇ formeleme ⁇ ten according to the preamble of claim 1.
• it is the manufacture of helical gears, in which the helical teeth are to be regarded as secondary form elements.
• the freely rotatably mounted lower punch is constantly engaged with the profile of the molding space and therefore inevitably rotates when there are linear relative movements between the lower punch and the die plate in the pressing cycle.
• a rotational movement corresponding to the helical teeth is forced on the upper punch from the outside during the pressing cycle in accordance with its depth of penetration, in order to reduce the friction between the outer surfaces of the upper punch and the mold space of the die.
• a gear transmission is provided which is driven via a mechanical link control corresponding to the desired helical toothing of the pressing body.
• the link control includes so-called link cores, which on the one hand are rigidly connected to a guide plate and on the other hand are positively and slidably guided in the coaxially arranged drive wheels of the gear transmission.
• the guide plate is temporarily firmly coupled to the die plate and moved together with it.
• the so-called pull-off method is used to mold the pressed body produced.
• the object of the invention is therefore to improve a generic device in such a way that the mentioned problem of friction is also solved satisfactorily with regard to the bottom, the tool and retrofitting effort required for the production of different pressed bodies should remain as low as possible.
• An essential feature of the invention is that the upper and lower punches directly involved in the shaping of the helical secondary form elements of the pressing body to be produced (for example, in the case of gearwheels with a plurality of toothings which lie axially one behind the other! Form space of the die are guided by an electronic control.
• the rotary movement of the lower and upper punches depending on their immersion depth in the mold space is no longer carried out by a mechanical coupling of linear and rotary drive, i.e.
• an embodiment of the invention provides that the axial and rotary movement of the stamp is position-controlled. To determine the respective axial and rotary position, appropriate sensors (e.g.
• the electronic control for the sequence of movements of the upper punch or dies can be set up in such a way that only a purely linear movement takes place outside the mold space of the die and that the required rotational movement in the press cycle only begins immediately upon immersion in the mold space.
• the position or torque control only comes into force when the upper punch has reached the stop. This prevents damage to the tool during immersion.
• Position control of the movement sequences is not always necessary to implement the invention.
• the rotary drives of the upper and lower punches are set in the pressing phase in such a way that the tooth flanks of the punches and the die jacket touch as far as possible only on the side which, in the absence of a rotary drive while the punches are retracted into the die cavity, would otherwise be a direct mutual would not be exposed to friction.
• the torque applied from the outside thus acts in the direction of the rotational movement otherwise forced by the shape.
• x ⁇ s. cot ß o where s is the tool play in the forehead cut. For example, for a 30 toothing and a tool play of 0.03 mm, this results in x ⁇ .0.05 mm.
• the molding of the pressed body produced by the ejection process can in principle be carried out without the use of rotary drives. However, it is recommended to use the rotary actuators in (partially) in the opposite way to that for the compression process. This ensures the greatest possible protection of the tool and the compact.
• Hydraulic drives should be used for the linear movement of the upper and lower punches (or the die, if applicable).
• the rotary drives can also be operated hydraulically. In some cases, they can also be pneumatic.
• Electromotive rotary drives are particularly recommended, in particular electric stepper or servo motors.
• the invention can be carried out expediently in connection with a CNC-controlled powder press. It is particularly advantageous to design the essential mechanical parts of the device according to the invention (punch, die, rotary drives) as an exchangeable unit in the form of a tool adapter in order to enable particularly short changeover times.
• the invention has the great advantage that it enables the production of, for example, helical toothed gears with extremely low tool wear, since the friction in the area of the tooth flanks during the pressing phase and also during the shaping is limited to a minimum can be.
• the retrofitting effort can also be significantly reduced compared to previously known pressing tools, since only program-technical precautions (no production of link cores) are required to effect the rotary drives.
• the device according to the invention enables the production of compacts which have a significantly more uniform density distribution than was previously possible.
• the device according to the invention is explained in more detail below on the basis of the exemplary embodiment of a metal powder press shown schematically in elevation in the single figure.
• This hydraulic press has a press frame 16 which is equipped with an upper piston 14 and a lower piston 15. Approximately in the middle of the press frame 16, a die 1 is mounted in a stationary and rotationally fixed manner. An upper plunger 2 is rotatably mounted in the upper piston 14 and a lower plunger 3 in the lower piston 15.
• the upper punch 2 is resiliently supported against the pressing direction by a prestressed spring 9, which presses the receiving device for the upper punch 2 in the pressing direction against a fixed stop.
• the spring force of the spring is in any case significantly less than the maximum pressing force that occurs for the respective tool, so that the upper punch is in contact with the stop as early as possible at the start of the pressing process.
• the jacket of the die 1 and the two punches 2, 3 have mutually corresponding helical teeth.
• two measuring systems 10, 11 are provided, which can be designed, for example, as an incremental measuring rod or linear potentiometer.
• a rotary drive 5 or 7 is attached to each of the two pistons 14, 15 (for example, an electric servo motor), the current angle of rotation position of which can be continuously recorded by means of a combined angle and torque measurement system 12 or 13.
• the punches 2, 3 have measuring devices 12a, 13a for detecting the torsional moment that occurs.
• the two rotary drives 5, 7 are each connected via a spur gear with one of the two punches 2 and 3 in terms of drive technology.
• the press shown also has an electronic control 8 (framed in dashed lines), which is hierarchically structured and consists of a CNC main processor 21, a control unit 19 and 20 for the linear movement of the upper piston 14 and the lower piston 15 and there is one control unit 17 and 18 for the rotary movement of the two punches 2 and 3, respectively.
• the input / output unit of the CNC main processor 21 for controlling and setting up the press by the operating personnel is designated by 22.
• the information technology linkage of the electronic components and sensors is symbolically represented by corresponding arrows.
• the two control units 19, 20 are each subordinate to the CNC main processor 21 and the control units 17, 18 for the rotary movement as slave to one of the two control units 19 and 20 for the linear piston movement.
• the control unit 19 is subordinate to the control unit 20 (submaster), that is to say that the movement of the upper piston 14 and thus the movement of the upper plunger 2 was used as a reference variable for the movement sequence.
• the combined angle and torque measuring system 12 forms, together with the rotary drive 5 and the control unit 17, a closed control loop, whereby. the control unit 17 receives its setpoint from the control unit 19 of the linear drive of the piston 14 in accordance with its current axial position detected by the displacement measuring system 10.
• the CNC main processor 21 takes over higher-level regulation and control functions as well as the processing of the specification data for the part to be manufactured.
• a dashed line indicates which main functional parts of the device according to the invention can be combined in the form of a tool adapter to form an easily replaceable structural unit which can be connected to upper and lower pistons 14, 15.
• the illustrated press works as follows:
• the lower punch 3 After shaping a press body, the lower punch 3 is moved position-controlled according to the helix angle of the helical gear to be manufactured using the rotary drive 7 on the basis of the actual values determined by the position measuring system 11 and the angle measuring system 12 into the filling position.
• the lower punch 3 remains immersed in the mold space of the die 1.
• the upper stamp 3 is located above the molding space.
• the upper punch 2 is moved downwards in a position-controlled manner by means of the control unit 19 on the basis of the data from the displacement measuring system 10.
• a coordinated rotary movement of the upper punch 2 is initiated via the control unit 17, the angle measuring system 12 and the rotary drive 5, so that the relative rotational position of the upper punch 2 to the toothing contour of the mold space of the die 1 permits the upper punch 2 to be immersed in the mold space without contact.
• This begins the actual pressing phase in which the steel powder introduced is compacted.
• the lower piston 3 and the upper piston 2 move in opposite directions into the mold space, the rotary drives 7 and 5, respectively, to minimize the friction between the stem 2, 3 and the die 1.
• the two angle measuring systems 12, 13 are also set up as instrument clusters for detecting the drive torque, torque control can also take place in addition or as an alternative to the position control of the rotary drive 5, 7 as a function of the axial position of the punches 2, 3.
• the drive system of the upper punch 2 is switched over to form the pressed body, ie the upper punch 2 is moved out of the molding space linearly and in a rotationally position-controlled manner according to the contour of the press body, with the lower piston 3 likewise being moved upward in a correspondingly position-controlled manner. until its upper end face is flush with the top of the die 1, so that the compact is exposed (ejection process).
• the compact can be held under a desired load.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Powder Metallurgy (AREA)
• Press Drives And Press Lines (AREA)
• Control Of Presses (AREA)
• Iron Core Of Rotating Electric Machines (AREA)
• Nonmetallic Welding Materials (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

Country Status (9)

Cited By (1)

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• 1994
  • 1994-08-02 DE DE4428842A patent/DE4428842C1/de not_active Expired - Fee Related
• 1995
  • 1995-06-07 DE DE29509762U patent/DE29509762U1/de not_active Expired - Lifetime
  • 1995-07-13 EP EP95925708A patent/EP0773846B1/fr not_active Expired - Lifetime
  • 1995-07-13 JP JP50608296A patent/JP4331793B2/ja not_active Expired - Fee Related
  • 1995-07-13 AT AT95925708T patent/ATE170115T1/de active
  • 1995-07-13 ES ES95925708T patent/ES2120218T3/es not_active Expired - Lifetime
  • 1995-07-13 DE DE59503369T patent/DE59503369D1/de not_active Expired - Lifetime
  • 1995-07-13 US US08/776,371 patent/US5906837A/en not_active Expired - Fee Related
  • 1995-07-13 CN CN95194316A patent/CN1074699C/zh not_active Expired - Fee Related
  • 1995-07-13 RU RU97103329A patent/RU2113940C1/ru not_active IP Right Cessation
  • 1995-07-13 WO PCT/DE1995/000954 patent/WO1996004087A1/fr active IP Right Grant

Non-Patent Citations (1)

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