GB2050889A - Pressure die casting - Google Patents
Pressure die casting Download PDFInfo
- Publication number
- GB2050889A GB2050889A GB8017425A GB8017425A GB2050889A GB 2050889 A GB2050889 A GB 2050889A GB 8017425 A GB8017425 A GB 8017425A GB 8017425 A GB8017425 A GB 8017425A GB 2050889 A GB2050889 A GB 2050889A
- Authority
- GB
- United Kingdom
- Prior art keywords
- pressure
- control
- storage device
- multiplier
- chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000004512 die casting Methods 0.000 title claims abstract description 12
- 230000004044 response Effects 0.000 claims abstract description 19
- 238000005266 casting Methods 0.000 claims description 7
- 238000002347 injection Methods 0.000 claims description 7
- 239000007924 injection Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000029058 respiratory gaseous exchange Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
- B22D17/20—Accessories: Details
- B22D17/32—Controlling equipment
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Fluid-Pressure Circuits (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
- Molding Of Porous Articles (AREA)
Abstract
In a pressure die casting machine the high pressure forces for the afterpressure phase are produced by means of a pressure multiplier (5, 6). The working pressure provided in chamber (4) by the multiplier piston (6) is controlled by the pressure in the annular counter pressure chamber (8) of the multiplier cylinder (5). The pressure in the counter pressure chamber (8) is adjusted by a pressure limiting valve (17) whose response threshold is determined by a control pressure storage device (26). In order to ensure a rapid build-up of afterpressure without overshoot or over-control at least the control pressure storage device (26) in the circuit arrangement (17, 19, 21, 25, 26, 33) precontrolling the pressure limiting valve (17) is constructed to be elastically deformable so that the circuit arrangement reacts to pressure fluctuations on attainment of the response threshold by the pressure in the counterpressure chamber (8) with an elastic closing force whose characteristic as a function of the valve travel is non- linear. <IMAGE>
Description
SPECIFICATION
Improvements relating to pressure die casting
The present invention relates to a pressure injection apparatus for a pressure die casting machine and to a die casting machine incorporating the apparatus.
More particularly it relates to an apparatus and machine comprising a pressure multiplier having a piston and a counter-pressure chamber for adjustment of pressure intensification in an after pressure phase following a mould filling phase of a casting cycle.
An apparatus known from German laid open specification 1901747 has a circuit arrangement which in a connecting conduit between the annular chamber of the multiplier and a pressure medium container, includes a pressure limiting valve and a control pressure storage device for the adjustment of the response threshold of the pressure limiting valve. That apparatus has as its control pressure storage device, a pressure accumulator consisting of a rigid vessel. This arrangement results in an unfavourable behaviour on the part of the pressure on response of the pressure limiting valve, and thus leads at maximum afterpressure, to a so-called "overshoot" and in the region of average afterpressure values to over-controlling of the preselected afterpressure.The overshoot or overcontrol must be counteracted by a suitably high closing force, with the constructional outlay which that involves, if the user is to avoid breathing of the mould such as can form burs on the casting and can involve the squirting out of liquid metal.
The present invention has as its object to provide an improved apparatus in which (subject to proper adjustment) the pressure exerted by the injection piston rises steeply at the end of the mould filling phase without overshoot or over-control, to the requisite afterpressure value, and does not vary during the afterpressure phase.
According to the invention we provide a pressure injection apparatus for a pressure die casting machine comprising a pressure multiplier having a piston and a counter-pressure chamber for adjustment of pressure intensification in an after pressure phase following a mould filling phase of a casting cycle, and a pressure medium container connected by way of a control circuit to the multiplier counter pressure chamber for control of the counterpressure therein, the control circuit including a pressure limiting valve and a control pressure storage device for adjustment of the response threshold of the pressure limiting valve, at least the control pressure storage device being elastically deformable.
The invention can achieve the advantageous effect that the closing force on the pressure limiting valve has a non-linear spring characteristic.
In addition to the advantage of avoiding overshooting or over-controlling of the afterpressure whilst having a steep pressure increase (which is here the primary concern), the invention affords the further advantage that at the pressure rise for the afterpressure phase it achieves a uniform steepness and a better afterpressure constancy even when low afterpressure values are chosen, likewise a reduction in the differences in the pressure build-up time with decreasing afterpressu re settings.
For further development of the subject of the present application, more particularly with regard to influencing the non-linear closing force characteristic, it may be arranged that the elastically deformable control pressure storage device may be provided as a storage capacity for the necessary closing pressure of the pressure limiting valve from a material having a spring characteristic extending non-linearly as a function of its deformation. Preferably the control pressure storage device is formed of a plurality of pressure vessels connected together, and these may be flexible pressure tubing elements or hoses. The control pressure storage device can also be arranged for connection to the control pressure chamber of the pressure limiting valve by means of a directional control valve controllable in dependence on pressure.This allows very precise timing of the actuation of the multiplier, and reliable prevention of premature release of the multiplier piston, more particular if the control pressure chamber of the pressure limiting valve is connectable to the annular chamber of the multiplier by the means of the directional control valve via a control conduit.
It is also possible to operate the directional control valve by means of an electrical control arrangement.
An embodiment of the invention will be described by way of example with reference to the accompanying diagrammatic drawings, wherein:
Figure 1 shows a part of the pressure injection apparatus with its hydraulic control system,
Figure 2 is a view on a larger scale of the pressure limiting valve connected between the multiplier annular chamber and the pressure medium container,
Figure 3 shows the spring characteristic of the closing force acting on the valve member of the pressure limiting valve, and
Figure 4 shows atime-pressure diagram of the mould filling operation in the case of a die casting machine during a casting operation.
Figure 1, for the sake of clarity, shows only those parts of a pressure die casting machine which are necessary for an understanding of the invention.
The reference numeral 1 designates the piston rod of a casting piston (not shown) of a pressure die casting machine, which is secured at its rear end to a drive piston 2. During a casting cycle the latter moves in a drive cylinder 3 in three successive movement phases from its rear end-position shown in the drawings into a front end-position, and then again into the rear end-position. At the rear end the drive cylinder 3 opens into a pressure multiplier cylinder 5 of relatively large diameter in which a multiplier piston 6 of known stepped type is axially displaceable. The multiplier piston 6 divides the interior space of the multiplier cylinder 5 into a pressure chamber 7 and an annular multiplier counter pressure chamber 8. The drive piston 2 itself divides the interior space of the drive cylinder 3 into a return pressure chamber 9 and a working pressure chamber 4.The multiplier piston 6 has its portion 12 of smaller diameter situated in the drive cylinder 3, and the diameter of that portion may be equal to the diameter of the drive piston 2. Provided in the multiplier piston 6 is a duct 11 which can be closed by a non-return valve 10 and which connects the pressure chamber 7 of the multiplier cylinder 5 with the working pressure chamber 4 of the drive cylinder 3. In the rear end-position shown in Figure 1 the multiplier piston 6 abuts against an abutment 13.
The pressure chamber 7 is connectable via a supply conduit 14 of a pressure medium storage device 16 by means of a shot valve 15.
The multiplier annular chamber 8 can be discharged via conduits 33,34 and a pressure limiting valve 17 situated between same into a pressure medium container 35. To act on the valve member 17' in the closing direction and to adjust the response threshold the control pressure chamber of the pressure limiting valve 17 is connected byway of a conduit 19 with a directional control valve 21, and also comprises a return spring 18.
The directional control valve 21 is connected via a conduit 20 to the multiplier annular chamber 8 and by way of a further conduit 25 to the control pressure storage device 26. Also, for its actuation, it comprises a connecting conduit 23 to the pressure medium storage device 16 and a connecting conduit 24 to the pressure chamber 7 of the multiplier cylinder 5.
From the start of the run-up phase up to near the end of the mould filling phase (cf. Figure 4) the slide of the directional control valve 21 occupies its end position on the right in Figure 1. As a result the valve member 17' of the pressure limiting valve 17 is acted upon in the closing direction via the conduits 19 and 20 bythe pressure prevailing at the time in the multiplier annular chamber 8 so that the multiplier piston 6 is held fast in its initial position shown in
Figure 1.The actuation of the directional control valve 21 for the purpose of connecting the control pressure storage device 26 to the control pressure chamber of the pressure limiting valve 17 is effected in known manner by the pressure rising at the end of a mould filling phase in the pressure chamber 7 of the multiplier cylinder 5, said pressure acting on the left-hand larger face of the valve slide piston in opposition to the pressure of the pressure medium storage device 16 effective at the right-hand smaller face of the valve slide piston. When the response threshold set by the pressure of the control pressure storage device 26 in the pressure limiting valve 17 is exceeded, because of the pressure in the annular chamber8 of the multiplier, the multiplier piston 6 is released.
The control pressure storage device 26 is supplied from the pressure medium storage device 16, which itself is charged from a pump connection P, by way of a conduit 27 and also a non-return valve 28 and a pressure reducing valve 29, which are situated in the conduit 27. In the arrangement shown in Figure 1 for example an electro-hydraulic pressure control valve 30 is provided for pre-control of the pressure reducing valve 29 and connected to the upstream side of said valve by way of a control conduit 31, and is also connected by means of a further conduit 32 to the pressure medium container 35.
In the constructional form shown in Figure 1 the control pressure storage device 26 comprises three pressure hoses 36 which are each connected at one end to the conduit 25 leading to the directional control valve 21 and which are closed at the other end. However, a different number of pressure hoses 36 could also be used depending on technical conditions.
The course of a three-phase mould filling operation, which can be carried out with the help of the pressure injection apparatus described, forms part of the generally known state of the art and need not be described here.
The operation of the embodiment of the present invention will be explained with reference to Figures 2to4.
The magnitude of the closing pressure exerted by the control pressure storage device 26 on the valve member 17' of the pressure limiting valve 17, i.e.. the response threshold of the pressure limiting valve 17 and thus also the magnitude of the afterpressure are determined on the one hand by the pressure in the pressure medium storage device 16 and on the other hand by the setting of the pressure reducing valve 29.
The circuit arrangement comprising the pressure limiting valve 17 with the return spring 18, the directional control valve 21, the control pressure storage device 26 composed of the pressure hoses 36, and also the conduits 19,25 and 33 connecting these parts to one another, forms in conjunction with the pressure fluid a system which deforms elastically when there are pressure variations.This system opposes a more or less rapidly increasing elastic closing force F against the pressure surges which act on the valve member 17' of the pressure limiting valve 17 and which occurs after the connecting of the control pressure storage device 26 tothe control pressure chamber of the pressure limiting valve 17 towards the end of the mould filling phase when the pressure in the multiplier annular chamber 8 approximates to the response threshold set at the pressure limiting valve 17.
The course of the elastic closing force F over the valve travel V is non-linear owing to the measures provided according to the invention to suppress overshoot or over-control of the afterpressure. It is illustrated with the help of Figures 2 and 3.
Figure 2 shows the pressure limiting valve 17. The static closing force acting on its valve member 17' is preset by the pressure in the pressure hoses 36 and by the force of the closing spring 18. However, the spring characteristic of the closing force F is additionally influenced by the elastic deformation and the volume of the pressure hoses 36, the conduits 25 and 19 and the valves 17 and 21.
Figure 3 shows the relation between the closing force F acting on the valve member 17' on the one hand and the valve travel V on the other. At the response threshold the opening force F' is equal to the closing force F (equilibrium of forces), the two forces F, F' differing only as regards sign. The S curve 37 which proceeds progressively at first and then in a decreasing sense characterises a relatively not very elastic circuit arrangement wherein already a small valve travel A V brings about a considerable closing force increase A F. In contrast, the S curve 38 characterises a circuit arrangement with relatively greater elasticity. The formation of these substantially S-shaped curves 37, 38 can be influenced by suitable choice of the aforesaid parameters.The larger the volume and the more elastic the material of the pressure hoses 36, the more does the development change from that of the curve 37 to that of the curve 38. For an optimum response of the pressure limiting valve 17 it is necessary for the S curve to have both at the start and also atthe end a region within which a relatively large valve travel A
V brings about a small closing force increase A F. It must be ensured that the valve member 17' lifts away from the valve seat at once both in response to a smaller closing force F (= high afterpressure) and also at a high closing force F (= low afterpressure) and abruptly frees a sufficient outflow cross-section for the pressure fluid held in the multiplier annular chamber 8.The magnitude of the afterpressure provided determines whether the degressively or progressively rising region of the S curve is used. If a low afterpressure is desired, the degressively rising upper end region of the S curve is used (broken line 44 indicates the response threshold for relatively low afterpressure settings). Conversely in the event of a high afterpressure the lower end region of the S curve (broken line 45 indicates the response threshold for higher after-pressure settings and reference numeral 46 represents the pre-loading force spring 18 plus the control pressure force).The adjusting of the response threshold of the pressure limiting valve 17 (magnitude of the afterpressure) and thus of the working region on the S curve is effected by the pressure reducing valve 29 with which the pressure in the control pressure storage device 26 is adjusted. In the view shown in Figure 3 it should be noted that the zero point for the valve travel V is displaced in the abscissa direction in accordance with the level of the response threshold (afterpressure magnitude).
The operation of the closing force characteristic described hereinbefore of the circuit arrangement will now be described with reference to Figure 4.
During a mould filling operation the drive piston 2 passes in known manner through the slow run up phase (indicated at 47), the rapid mould filling phase 48 and finally the afterpressure phase 49, for only a relatively small displacement. The pressure in the working pressure chamber 4 rises in a likewise known manner in three stages as shown by the curve 39 in Figure 4. The pressure during the mould filling phase is indicated at 50 and at the end of the mould filling phase there is a rise in pressure (indicated at 51) against the resistance of the incompressible metal introduced into the mould, whereupon the non-return valve 10 closes, and the multiplier piston 6 is acted upon fully from the pressure chamber 7, and then is set in motion after attainment of the response threshold of the pressure limiting valve 17.In the pressure curve 39 a short-duration pressure peak occurs at 40 owing to the sudden braking of the drive piston 2, and then a pressure drop because of elastic reaction of the system during the change-over operation. This pressure drop is followed by a further steep pressure rise to the level of the adjusted afterpressure. If the maxhffum possible afterpressure 52 is provided for, the pressure pattern follows the curve portion shown in full-line. At 41 the pressure only slightly rises above the desired afterpressure, and at once falls back thereto. On the other hand if a medium afterpressure 53 or the minimum afterpressure 54 is pr6vided for the afterpressure phase (shown in broken lines in
Figure 4) it is attained with an only slight, practically insignificant time delay and without any overcontrol.
In contrast the chain-dotted curves S show the pressure development such as occurs in the known prior art apparatus. The undesirable overshoot (maximum afterpressure) and over-control (medium afterpressure) can be seen clearly here. This is due to the fact that in the known old apparatus the pressure limiting valve is acted upon by a closing force F which has a linear characteristic as a function of the valve travel V (shown in chain-dotted lines in Figure 3).
To inhibit overshoot or over-control of afterpressure effectively it is important that the characteristic of the closing force has a non-linear region with a progressively or degressively rising characterfol- lowing the response threshold.
The apparatus described above for controlling the counterpressure in the annular chamber 8 of the multiplier 5,6 also allows, additionally to obviating afterpressu re fluctuations, unform steepness of pressure rise and a better constancy of the set afterpressure even where low afterpressure values are chosen, besides a reduction in the differences in pressure build-up time with decreasing afterpressure settings.
Claims (9)
1. Pressure injection apparatus for a pressure die casting machine comprising a pressure multiplier having a piston and a counter-pressure chamber for adjustment of pressure intensification in an after pressure phasefollowing a mould filling phase of a casting cycle, and a pressure medium container connected by way of a control circuit to the multiplier counter pressure chamber for control of the counterpressure therein, the control circuit including a pressure limiting valve and a control pressure storage device for adjustment of the response threshold of the pressure limiting valve, at least the control pressure storage device being elastically deformable.
2. Apparatus according to claim 1 wherein the elastically deformable control pressure storage device comprises a storage capacity for the requisite closing pressure of the pressure limiting valve and is formed of a material having a spring characteristic which is non-linear as a function of its deformation.
3. Apparatus according to claim 1 or claim 2 wherein the control pressure storage device is formed of a plurality of pressure vessels connected together.
4. Apparatus according to claim 3 wherein the pressure vessels are flexible pressure tubes.
5. Apparatus according to any one of the preceding claims wherein the control pressure storage device is arranged for connection to a control pressure chamber of the pressure limiting valve by way of a directional control valve controllable in dependence of pressure.
6. Apparatus according to any one of the preceding claims wherein a control pressure chamber of the pressure limiting valve is arranged for connection to the multiplier counterpressure chamber under the control of a directional control valve via a control conduit.
7. Pressure injection apparatus for a pressure die casting machine, the apparatus being constructed and arranged for use and operation as shown in and hereinbefore described with reference to the accompanying drawings.
8. A pressure die casting machine incorporating apparatus according to any one of the preceding claims for adjustment of pressure intensification in an after pressure phase.
9. Pressure die cast articles whenever made by a machine according to claim 8.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH565079 | 1979-06-18 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2050889A true GB2050889A (en) | 1981-01-14 |
| GB2050889B GB2050889B (en) | 1983-04-27 |
Family
ID=4297126
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8017425A Expired GB2050889B (en) | 1979-06-18 | 1980-05-28 | Pressure die casting |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS564365A (en) |
| BE (1) | BE883850A (en) |
| DE (1) | DE3014868A1 (en) |
| ES (1) | ES8101429A1 (en) |
| FR (1) | FR2459096A1 (en) |
| GB (1) | GB2050889B (en) |
| IT (1) | IT1132069B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1991017850A1 (en) * | 1990-05-22 | 1991-11-28 | International Press Development Establishment | Injection unit for a hydraulic die-casting machine, provided with a device for the elimination of pressure peaks at injection |
| DE102008055536A1 (en) * | 2008-12-17 | 2010-07-01 | Bühler Druckguss AG | Method for operating a drive piston of a die casting machine and device for carrying out the method |
| CN104923758A (en) * | 2014-03-21 | 2015-09-23 | 意特佩雷斯工业公司 | Die-casting machine with injection assembly |
| CN108188371A (en) * | 2018-01-18 | 2018-06-22 | 宁波海天金属成型设备有限公司 | The differential oil line system that injection controls in real time in a kind of die casting machine |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3446836A1 (en) * | 1984-12-21 | 1986-07-03 | Mahle Gmbh, 7000 Stuttgart | DEVICE FOR PRESSURE TIP PREVENTION IN THE PRESSING UNIT OF A DIE CASTING MACHINE |
| BE1010155A6 (en) * | 1997-11-05 | 1998-01-06 | Buehler Ag | Method for operating a drive piston and device for the implementation thereof. |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB786402A (en) * | 1956-02-22 | 1957-11-20 | Finney Presses Ltd | Accumulators or shock absorbers for hydraulic pressure systems |
| CH486939A (en) * | 1967-12-18 | 1970-03-15 | Vihorlat N P Snina Vyvojove St | Press mechanism with multiplier in a press casting machine for metal |
| DE2021539B2 (en) * | 1970-05-02 | 1971-04-22 | Wotan Werke Gmbh | DIE CASTING MACHINE WITH MULTIPLIER |
| DE1901747A1 (en) * | 1968-10-19 | 1970-06-18 | Triulzi Spa | Spray casting machine pressure controller |
| DE2060681A1 (en) * | 1970-12-10 | 1972-06-15 | Wittmann Ag Gusstahlwerk | Device for controlling the pressure curve on the press-fit part of casting machines |
| DE2401471A1 (en) * | 1974-01-12 | 1975-07-24 | Idra Pressen Gmbh | PRESSED PART ON COLD CHAMBER DIE CASTING MACHINES WITH MULTIPLIER WORKING ACCORDING TO THE MULTI-PHASE PRINCIPLE |
| DE2406528C2 (en) * | 1974-02-12 | 1982-04-01 | Idra Pressen GmbH, 7000 Stuttgart | Control device for a die-casting machine that works according to the multiphase principle |
| GB1582533A (en) * | 1976-08-03 | 1981-01-07 | Idra Pressen Gmbh | Die-casting machine |
-
1980
- 1980-04-17 DE DE19803014868 patent/DE3014868A1/en not_active Withdrawn
- 1980-05-28 GB GB8017425A patent/GB2050889B/en not_active Expired
- 1980-06-03 IT IT22523/80A patent/IT1132069B/en active
- 1980-06-16 ES ES492477A patent/ES8101429A1/en not_active Expired
- 1980-06-17 BE BE0/201051A patent/BE883850A/en unknown
- 1980-06-17 FR FR8013428A patent/FR2459096A1/en not_active Withdrawn
- 1980-06-18 JP JP8154480A patent/JPS564365A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1991017850A1 (en) * | 1990-05-22 | 1991-11-28 | International Press Development Establishment | Injection unit for a hydraulic die-casting machine, provided with a device for the elimination of pressure peaks at injection |
| DE102008055536A1 (en) * | 2008-12-17 | 2010-07-01 | Bühler Druckguss AG | Method for operating a drive piston of a die casting machine and device for carrying out the method |
| CN104923758A (en) * | 2014-03-21 | 2015-09-23 | 意特佩雷斯工业公司 | Die-casting machine with injection assembly |
| EP2942127A1 (en) * | 2014-03-21 | 2015-11-11 | Italpresse Industrie S.p.A. | Die-casting machine with injection assembly with a shut-off valve |
| CN104923758B (en) * | 2014-03-21 | 2018-11-06 | 意特佩雷斯工业单一合伙责任有限公司 | Fill assembly for hydraulic die-casting machine |
| EP3501691A1 (en) * | 2014-03-21 | 2019-06-26 | ITALPRESSE INDUSTRIE S.p.A. | Incection assembly provided with a shut-off valve for a die-casting machine |
| CN108188371A (en) * | 2018-01-18 | 2018-06-22 | 宁波海天金属成型设备有限公司 | The differential oil line system that injection controls in real time in a kind of die casting machine |
| CN108188371B (en) * | 2018-01-18 | 2024-04-19 | 宁波海天金属成型设备有限公司 | Differential oil circuit system for real-time control of injection in die casting machine |
Also Published As
| Publication number | Publication date |
|---|---|
| IT8022523A0 (en) | 1980-06-03 |
| BE883850A (en) | 1980-10-16 |
| ES492477A0 (en) | 1980-12-16 |
| FR2459096A1 (en) | 1981-01-09 |
| GB2050889B (en) | 1983-04-27 |
| ES8101429A1 (en) | 1980-12-16 |
| DE3014868A1 (en) | 1981-01-22 |
| JPS564365A (en) | 1981-01-17 |
| IT1132069B (en) | 1986-06-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |