US3592032A - Control means for hydrostatic extrusion - Google Patents

Control means for hydrostatic extrusion Download PDF

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Publication number
US3592032A
US3592032A US837537A US3592032DA US3592032A US 3592032 A US3592032 A US 3592032A US 837537 A US837537 A US 837537A US 3592032D A US3592032D A US 3592032DA US 3592032 A US3592032 A US 3592032A
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United States
Prior art keywords
pressure
calculator
billet
punch
emitter
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Expired - Lifetime
Application number
US837537A
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English (en)
Inventor
Ingemar Stromblad
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ABB Norden Holding AB
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ASEA AB
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C23/00—Extruding metal; Impact extrusion
    • B21C23/007—Hydrostatic extrusion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C31/00—Control devices for metal extruding, e.g. for regulating the pressing speed or temperature of metal; Measuring devices, e.g. for temperature of metal, combined with or specially adapted for use in connection with extrusion presses

Definitions

  • ABSTRACT For the control of a press which includes a press stand, an operating cylinder carried by the stand and having an operating piston therein, a pressure chamber arranged in the stand and an extrusion die in the chamber, with a pressuregenerating punch connected to the operating piston and inserted in the pressure chamber for compressing a pressure medium isostatically around the billet, a position indicator and a pressure indicator are provided which are connected to a calculating unit to sense when extrusion starts and to calculate, depending on the size of the billet, the allowable movement of the pressure-generating punch, which is interrupted just before the last of the billet is extruded.
  • the present invention relates to a means for controlling the extrusion process during hydrostatic extrusion in such a way that complete extrusion of the billet through the die is avoided and so that the production rate is high, that is, that only a small quantity of material remains in the die when the extrusion is interrupted.
  • the Prior Art For hydrostatic extrusion a billet is enclosed in a pressure chamber having a die with an opening of desired cross section and subjected to high-hydrostatic pressure all round so that the material is extruded through the opening.
  • the equipment usually consists of a wire or strip-wound high-pressure cylinder which is inserted in a hydraulic press. The cylinder is closed at one end by a die having an opening with the desired cross section of the component.
  • the pressure is generated by a punch which is pressed by a hydraulic operating piston into the high-pressure cylinder filled with liquid. Usually pressures of between and 25 kilobar are used. At these high pressures the liquid compression is also considerable, often more than percent, and the energy in the compressed liquid is great.
  • the press is provided with a position-indicator which senses the position of the pressure-generating punch and a pressureemitter which senses the pressure in the operating cylinder which drives the punch.
  • the press contains a calculator with at least one memory unit and at least one calculating unit, which calculator receives the output signals of the indicator and emitter and, with the guidance of these signals, senses when extrusion starts and, depending on the size of the billet, calculates the allowable movement of the pressuregenerating punch and interrupts the extrusion when the desired volume has been extruded.
  • the pressure in the pressure cylinder itself is thus measured indirectly since the high pressure does not permit connections to the pressure chamber through the wall of the cylinder or the punch.
  • the entire extrusion equipment can be calibrated by registering the output signals of the indicator and the emitter at known volumes of the billet in the pressure chamber and storing these signals in the memory unit.
  • the volume of the billets intended to be extruded need not be known. Because during the extrusion the output signals of the indicator and emitter are supplied to the calculator and compared with the values of the output signals stored in the memory part which were obtained during the calibration with known billet volumes, the calculator determines the volume of the billet in question according to a pro gram which has been fed in and the difference between the measured values.
  • the start of the extrusion is indicated by at least one emitter which senses when the extrusion is indicated by at least one emitter which senses when the extrusion starts and the output signal of this emitter is also supplied to the calculator.
  • the previously mentioned indicator and emitter are suitably also used to indicate the start of the extrusion process, the calculator for example analyzing the relationship between the punch position and the pressure and sensing a certain point at the start of the extrusion process because the derivative of the function then rapidly decreases towards zero.
  • the calculator is programmed to determine how much further the punch must be inserted into the cylinder in view of the calculated volume of the billet after the start of the extrusion process has been indicated and to interrupt the feeding or reverse the movement of the punch when the calculated infeeding has been obtained.
  • Calculators of both digital and analogue type can be used.
  • a single calculator may control one, two or more presses.
  • the invention enables much better utilization of the material than was previously possible.
  • the measurements can be rapidly reproduced and the volume of the billet in question can be determined with great accuracy.
  • the position of the punch when the extrusion process should be interrupted can therefore also be determined with great safety.
  • the error in calculation may be 5 percent or lower. Even when great safety against complete extrusion is desired, it is possible to utilize percent of the material or more.
  • FIG. 1 shows the ratio between the pressure in a pressure cylinder and the movement of a punch inserted into the cylinder to generate the pressure for extrusion of a billet inserted in the pressure cylinder.
  • FIG. 2 shows schematically the parts essential for the invention in a press for hydrostatic extrusion and certain auxiliary equipment for adjusting the press.
  • the slope of the curve is in this part a function of the spring action of the press stand, the volume increase of the cylinder due to its suspension, the compression of the punch, die and billet and of the volume and compressibility of pressure medium enclosed in the pressure cylinder.
  • the volume of the pressure medium is in turn a function of the billet volume under otherwise constant conditions.
  • the slope of the curve alters noticeably and a maximum is obtained at The derivatives of the curve thus alter from a constant value to O at this part.
  • the position 8 such a pressure has been attained that a certain deformation of the front part of the billet projecting into the die is obtained.
  • the pressure has reached such a value that the extrusion process through the die opening is initiated.
  • the pressure medium which has a pressure of -20 kilobar may also directly damage those parts with which it comes into contact.
  • the movement of the punch is interrupted at S,,. If the punch is only stopped the extrusion continues under decreasing pressure and stops when the pressure has dropped to a certain level. If, however, the movement of the punch is at a reversed at position S the extrusion is stopped almost instantaneously.
  • Curve B indicates the pressure in the pressure cylinder as a function of the pressure in the operating cylinder for the punch. This pressure is proportional to the pressure in the cylinder and can therefore be utilized to determine the pressure in the extrusion cylinder.
  • FIG. 2 designates a press table, 2 an operating cylinder in a hydraulic press not otherwise shown.
  • a highpressure cylinder 3 formed by a steel cylinder 4, a strip sheath 5 of wire having rectangular cross section and great strength wound on under prestressing, and ends 6 and 7.
  • the cylinder are a lining 8, a die 9 and sealing rings 10 and III which seal between the cylinder 4 and the die 9 with respect to a pressure-generating punch 12.
  • a seal 113 which seals between the end and the punch 12 while the cylinder is being filled with pressure medium from the cylinder space 14 through a channel 15 in the end 7 before the punch 112 is inserted to generate the pressure necessary for the extrusion process.
  • the press is of the type which has a horizontal, axially movable pressure cylinder in which a billet l6 and a new die 9 are inserted from the side of the press table in the space 18 and where the billet l6 and die 9 are held in the correct position by a piston 17 freely movable in the lining 8, the piston pressing the billet and the die against the table I while the cylinder 3 is returned to the press table.
  • the pressure force is obtained by pressure medium in the space 14 influencing the piston 17 which is pressure determined by spring-loaded overflow valves in the piston 17.
  • the punch 12 is joined to the piston 19 which is influenced in the direction of the press table 1 by the pressure in the space 20.
  • the punch is operated in the opposite direction by operating cylinders, not shown.
  • the space 20 communicates through conduit 27 and a valve 21 operated by an electromagnet 22 with either a pump 23 and a pressure medium container 24 or a collection container 25. If a continuously operating pump is used the pressure medium can be transferred through the same valve directly to the collecting container 25.
  • a pressure-emitter 28 is connected by a tube 29 to the tube 27 and thus measures the pressure in the space 20 and thus indirectly the pressure inside the cylinder 3.
  • a resistive position-indicator 30 having a stationary part 31 in the press stand and a part 32 joined to the piston 19, with a trailing contact 33 which fol lows the piston 19 and the punch 12 during their movement.
  • the pressure-emitter 28 and the position-indicator 30 are connected to a calculator which is connected both to an operating table 35, a recorder 36 and the operating unit 22 of valve 21, as well as other operating units for the press, not shown.
  • the equipment operates in the following way. It is calibrated before the extrusion process is started so that the spring constant" of the equipment is known by determining the relationship between the punch movement and the pressure in the cylinder 3 at a known volume of the billet 116.
  • the pressure in the cylinder 3 is measured indirectly through the emitter 28 which measures the pressure of the pressure medium in the space 20 which influences the operating piston 19 which drives the pressure-generating punch 12 into the cylinder 3.
  • the movement of the punch 12 is measured by the resistive position-indicator 30.
  • the output signals of both emitter and indicator are supplied to the calculator 34 and inserted in its memory unit.
  • a billet 16 is inserted in the pressure cylinder. This may be of arbitrary size, within certain limits.
  • the press is started and the values of the pressure-emitter 28 and the position-indicator 33 are supplied to the calculator 34 and the ratio between pressure and punch movement is compared with the calibration values stored in the memory unit. Because the compressibility of the pressure medium is greater than that of the metallic billet (approximately 15 percent and 2 percent, respectively at 10 kilobar), different volumes of the billet and pressure medium cause the slope of the curve in the area S S to differ from that of the curve registered during the calibration. The difference in slope, the derivative of the curve, is a gauge of the difference between billet volumes.
  • the punch When the punch is in position 5;, the pressure has dropped, in spite of constant speed of the punch, to a value which continues to be constant.
  • the alteration of the curve derivatives can be used to determine the position of the punch 16 when the extrusion starts.
  • the calculator may be programmed, when the curve derivatives pass zero, to calculate, with the help of the calculated billet volume, the distance 5 -8. the punch must travel further into the cylinder so that, with the desired degree of safety against complete extrusion of the material, the least possible material is left which must be scrapped.
  • the calculator 34 may be programmed to give a control signal to a valve unit which interrupts the supply of pressure medium to the space 20 so that the pressure remains and the extrusion continues until the flow of material ceases at a certain lower pressure.
  • a control signal may be sent to the operating member 22 in a valve 2] according to FIG. 2, which immediately unloads the cylinder 2 by placing it in communication with a collecting container 24 for the pres sure medium.
  • the calculator 34 is connected to an operating panel with operating buttons and adjusting knobs for operating the press,
  • the calculator may also be connected to a recorder for recording production statistics from the calculator.
  • a press comprising a press stand, an operating cylinder arranged in the stand and having an operating piston, a pressure chamber arranged in the stand and an extrusion die arranged in the chamber, a pressure-generating punch connected to the operating piston to generate the required pressure in a pressure medium enclosed in the pressure chamber which isostatically influences a billet in the pressure chamber and a position-indicator which senses the position of the punch and a pressure-emitter means which senses the pressure in the operating cylinder, the improvement comprising a calculator with at least one memory unit and at least one calculating unit, means to supply to the calculator the output signals of the indicator and emitter, said calculator including means responsive to these signals to sense when extrusion starts and, depending on the size of the billet, to calculate the allowable movement of the pressure-generating punch and to interrupt the extrusion when the desired volume has been extruded.
  • said calculator comprising means to compare the output signals of the pressure-emitter means produced by billets of unknown volume with the values of the output signals at known volumes, so that the calculator calculates the volume of the billet with the help of the diffcrence.
  • Means according to claim 4, which has at least one emitter which senses when the extrusion starts and means to supply the output signal of said emitter to the calculator.
  • the calculator includes means to determine according to a program which is fed distance the pressure-generating punch is to be inserted into the pressure chamber and to deliver an output signal which interrupts the feeding when the punch has been fed in the calculated distance.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Presses (AREA)
  • Extrusion Of Metal (AREA)
  • Forging (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)
US837537A 1968-07-02 1969-06-30 Control means for hydrostatic extrusion Expired - Lifetime US3592032A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE09077/68A SE326932B (enrdf_load_stackoverflow) 1968-07-02 1968-07-02

Publications (1)

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US3592032A true US3592032A (en) 1971-07-13

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US837537A Expired - Lifetime US3592032A (en) 1968-07-02 1969-06-30 Control means for hydrostatic extrusion

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US (1) US3592032A (enrdf_load_stackoverflow)
FR (1) FR2012139A1 (enrdf_load_stackoverflow)
GB (1) GB1263490A (enrdf_load_stackoverflow)
SE (1) SE326932B (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3810374A (en) * 1972-02-07 1974-05-14 A Zeitlin Apparatus and method for hydrostatic extrusion
US3851511A (en) * 1972-09-14 1974-12-03 Asea Ab Method for hydrostatic extrusion
US5657661A (en) * 1992-12-22 1997-08-19 Mannesmann Aktiengesellschaft Working method for loading an extrusion billet and metal extrusion press
US20070131013A1 (en) * 2003-07-25 2007-06-14 Segal Vladimir M Method and apparatus for equal channel angular extrusion of flat billets
CN113118229A (zh) * 2021-04-16 2021-07-16 广东言铝铝业有限公司 一种铝棒挤压机

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2558035A (en) * 1947-07-05 1951-06-26 Percy W Bridgman Method and apparatus for cold drawing
US3491565A (en) * 1966-08-17 1970-01-27 Barogenics Inc Equipment adapted for hydrostatic extrusion and other uses

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2558035A (en) * 1947-07-05 1951-06-26 Percy W Bridgman Method and apparatus for cold drawing
US3491565A (en) * 1966-08-17 1970-01-27 Barogenics Inc Equipment adapted for hydrostatic extrusion and other uses

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3810374A (en) * 1972-02-07 1974-05-14 A Zeitlin Apparatus and method for hydrostatic extrusion
US3851511A (en) * 1972-09-14 1974-12-03 Asea Ab Method for hydrostatic extrusion
US5657661A (en) * 1992-12-22 1997-08-19 Mannesmann Aktiengesellschaft Working method for loading an extrusion billet and metal extrusion press
US20070131013A1 (en) * 2003-07-25 2007-06-14 Segal Vladimir M Method and apparatus for equal channel angular extrusion of flat billets
US7380432B2 (en) * 2003-07-25 2008-06-03 Engineered Performance Materials Co., Llc Method and apparatus for equal channel angular extrusion of flat billets
CN113118229A (zh) * 2021-04-16 2021-07-16 广东言铝铝业有限公司 一种铝棒挤压机

Also Published As

Publication number Publication date
GB1263490A (en) 1972-02-09
FR2012139A1 (enrdf_load_stackoverflow) 1970-03-13
DE1932662B2 (de) 1976-10-07
SE326932B (enrdf_load_stackoverflow) 1970-08-10
DE1932662A1 (de) 1970-08-20

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