EP0273340A1 - Pneumatic device for presses - Google Patents
Pneumatic device for presses Download PDFInfo
- Publication number
- EP0273340A1 EP0273340A1 EP87118917A EP87118917A EP0273340A1 EP 0273340 A1 EP0273340 A1 EP 0273340A1 EP 87118917 A EP87118917 A EP 87118917A EP 87118917 A EP87118917 A EP 87118917A EP 0273340 A1 EP0273340 A1 EP 0273340A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cylinder
- piston
- power
- shaft
- die
- 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.)
- Withdrawn
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
- B30B15/16—Control arrangements for fluid-driven presses
- B30B15/161—Control arrangements for fluid-driven presses controlling the ram speed and ram pressure, e.g. fast approach speed at low pressure, low pressing speed at high pressure
Definitions
- the invention concerns the realization of a pneumatic device including a pneumatic power cylinder with special accident-prevention characteristics and functioning with limited air consumption, particularly suited to be installed in presses for the lifting and lowering of the upper part of the die.
- Said presses usually have two pneumatic cylinders with co-ordinated action.
- the first one which is not very powerful and is called “service” cylinder, lowers and lifts - through the inlet of air under pressure - the upper part of the die with a power which is barely sufficient to move the mass connected with it, so that the working punch approaches the working area without actually transmitting any useful power.
- the shaft of said service cylinder is equipped with a suitable ledge, which, during the downward stroke of the piston itself, goes to touch a micro-switch being integral with the press and controlling a main cylinder.
- said second cylinder which is the power cylinder of the press and it transmits to the piston connected to the punch the strength necessary to perform the working process with the die.
- the just described double-cylinder press is actually equipped with an accident preventing safety device, in that the second cylinder, which is the power-giving one, only begins to function almost at the end of the stroke of the first service cylinder, i.e. shortly before the shutting of the die.
- the second cylinder which is the power-giving one
- the second cylinder only begins to function almost at the end of the stroke of the first service cylinder, i.e. shortly before the shutting of the die.
- the press operator were accidentally to place his hand or a finger under the die, this would happen before the power cylinder of the press begins to perform and the operator's limb would only receive a slight blow from the service cylinder, i.e. a blow of only a few kilograms.
- the hand itself would prevent the service cylindr from completing its stroke and , therefore, the power cylinder would be prevented from functioning.
- the goal of the present invention is that of overcoming the just mentioned drawbacks.
- the goal is that of obtaining a pneumatic device including a pneumatic power cylinder suited to be applied to presses, where the pneumatic cylinder can be stopped without any damage by exerting a minimum amount of pressure, should it meet with an obstacle during its stroke.
- the proposed goal is that, in case of the accidental presence of the operator's hands under the die, the operator may receive only a minimum damage, i.e. a blow of negligible power and of very little effect, such that it will not damage the involved limb.
- Yet another purpose to be reached is that of realizing a device with a pneumatic power cylinder requiring a low air consumption in comparison with cylinders of equal power of the known construction types.
- a pneumatic device suited to be employed on presses, characterized by the fact that it consists of two pneumatic cylinders having different diameters, communicating with each other and equipped with two different pistons rigidly connected with each other, further characterized by the fact that the descent of the shaft connected with the upper part of the die, prior to the shutting of the die, is obtained by the reduced thrust of the piston of the pneumatic cylinder having the smaller diameter, while the last part of the descent of the shaft corresponding with the shutting of the die, occurs thanks to the thrust of the piston belonging to the cylinder having the larger diameter, said thrust being equal to the nominal power of the press.
- the two pneumatic cylinders are coaxial with each other and they have their two respective pistons connected by a rigid shaft coaxial with the shaft of the main piston protruding from the cylinder and connected to the upper part of the working die.
- the upper cylinder has a significantly smaller diameter than the lower cylinder, so that, the air pressure being equal, the power of the upper cylinder is negligible in comparison with the power of the lower pneumatic cylinder.
- the diameter of the lower cylinder is not constant, but it rather presents, in its lower terminal part, a stretch having a diameter slightly reduced in comparison with its own diameter. This because the goal is that of making the piston of the lower cylinder work only in correspondence with the reduced diameter, as mentioned above.
- the air under pressure enters into the upper cylinder having a smaller diameter and it exerts on the piston a considerably reduced thrust of negligible power, such as to cause the shaft of the cylinder to descend until the piston of the lower cylinder having a larger diameter reaches the terminal part of said cylinder.
- the piston of said cylinder gets into contact with the walls of the chamber of the cylinder itself, since the diameter of said lower part is equal to the diameter of the piston.
- the air discharged by a valve activated by the piston itself is let into the smaller chamber which is created by the descent of the lower piston, said piston is subject to the thrust exerted by the air in the remaining part of the lower cylinder, said thrust being exerted only on the upper part of the piston.
- One of the advantages obtained with the device of the invention is that the thrust exerted on the upper part of the die prior to the shutting of the die is controlled by the cylinder with the negligible power which is barely sufficient to overcome the frictions and to move the masses connected with the device.
- the operator's hands were under the die, they would be hit by a power of only a few kilograms which would not entail traumatic effects.
- the pneumatic device according to the invention consists of a hollow cylinder 1 connected with another cylinder 2 by means of a junction cap 3, said cylinder 2 being coaxial with the first one and having a larger diameter.
- the cylindrical bodies 1 and 2 are constantly communicating with one another thanks to the manifold hole 4 obtained on cap 3 and also thanks to the fact that there is a backlash between shaft 7 of piston 5 and bushing 8 on which shaft 7 slides.
- Said shaft 7 is coupled so it can slide with a splined bushing 8 contained within the junction cap 3, so as to avoid the rotation of the shaft itself and, therefore, the possible rotation of the punch.
- the just mentioned pistons also divide the cylindrical bodies 1 and 2 into a series of chambers with variable volume in relation to the stroke of the pistons themselves.
- Chamber 12 is located in cylinder 1 above piston 5 and it communicates through duct 13 with a header 14 which sends in air under pressure.
- Chamber 15 is located in cylinder 1 between piston 5 and the junction cap 3 and it communicates with chamber 16, located in cylinder 2 between piston 6 and cap 3 itself, through duct 4.
- Chamber 16 communicates also, through duct 17, with header 18 which sends air under pressure into cylinder 2.
- header 18 When air is let in through header 18, it flows through duct 17 and expands in the chambers 15 and 16, communicating with each other, and in chamber 19 further communicating with chamber 16, since the diameter of piston 6 is smaller than the maximum internal diameter of the cylindrical body 2, as can be observed in Fig. 1.
- the cylindrical body 2 presents internally two different diameters, i.e. a larger diameter in correspondence with chamber 16 and a smaller one in correspondence with chamber 19, where piston 6 can perform its action, its diameter being compatible.
- valve 21 While piston 6 is exiting from chamber 19, valve 21 is gradually recalled by spring 26 and it shuts again the passage to the air. Since washer 24 no longer effects the air tightness, the pressure existing in chamber 19 enters also into the chambers 15 and 16 and the force necessary to lift the pistons will again be given by the difference between the thrusts exerted on the lower part 20 and on the upper part 27 of piston 6.
- FIG. 3 An execution variation of the just described device according to the invention, especially suited when the shutting stroke of the die is sufficiently long, is illustrated in Fig. 3.
- the device according to the invention is made so that cylinder 31, which controls the descent of the upper part of the die, and cylinder 32, which is the power cylinder, are placed parallel side by side.
- the shafts 33 of cylinder 31 and 34 of cylinder 32 are connected with each other by means of shaft 35 which is integral with two bushings 56 and 57 keyed on the shafts 33 and 34 respectively.
- the pneumatic connections and the mechanical structure inside the two cylinders are practically unchanged in relation to device 10 of the Figs. 1 and 2, exception being made for the discharge valve which, in the case of Fig. 3, is controlled by a selenoid valve.
- valve 36 discharging the air in chamber 37 having a smaller diameter than chamber 38, both belonging to the power cylinder 32, is controlled by a selenoid valve 39, which is activated when piston 40 of cylinder 32 lowers itself until it touches the proximity sensor 41.
- valve 36 lets out through duct 42 all the air contained in chamber 37.
- Said valve continues to let out the air until piston 40 completes its descending stroke, after that the control circuit of the device - which is not represented in the drawings, since it is of a well-known type and rather obvious to the expert in the business, controls the inlet of air under pressure into chamber 37 through the same duct 42, which was previously functioning as an air outlet duct, and at the same time it controls the discharge of the air contained in chamber 43 of cylinder 31 through duct 44.
- FIG. 4 A variation of the same inventive idea concerning a different method of air discharge is represented in the Figs. 4 and 5.
- said variation will be referred to the Figs. 1 and 2, but it is equally valid if it is applied to the variation illustrated in Fig. 3.
- shaft 9 for the connection of piston 6 presents an area 60 with an indented diameter.
- Shaft 9 slides within seat 61 obtained in the bottom flange 62, where the tightness between seat 61 and shaft 9 is guaranteed by the presence of the washers on lip 63.
- a horizontal duct 64 is also obtained. It communicates with seat 61 in the area comprised between the two washers 63 and it allows said area to be in communication with the outside environment.
- Yet another advantage consists in the possibility of realizing bottom flanges 65 having a reduced thickness, since it is no longer dependent on the stroke length of valve 21.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Actuator (AREA)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT8785501A IT1210548B (it) | 1987-01-02 | 1987-01-02 | Pneumatico per presse. |
| IT8550187 | 1987-01-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0273340A1 true EP0273340A1 (en) | 1988-07-06 |
Family
ID=11327090
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP87118917A Withdrawn EP0273340A1 (en) | 1987-01-02 | 1987-12-21 | Pneumatic device for presses |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0273340A1 (it) |
| IT (1) | IT1210548B (it) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2733399A1 (de) * | 1977-07-23 | 1979-02-01 | Knaebel Horst | Vorrichtung fuer die hochleistungsumformtechnik zum erzeugen einer schlagartigen belastung oder verformung (arbeitsphase) - jeweils innerhalb weniger millisekunden oder innerhalb von bruchteilen davon - eines zu bearbeitenden und/oder zu verformenden koerpers und steuerung |
-
1987
- 1987-01-02 IT IT8785501A patent/IT1210548B/it active
- 1987-12-21 EP EP87118917A patent/EP0273340A1/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2733399A1 (de) * | 1977-07-23 | 1979-02-01 | Knaebel Horst | Vorrichtung fuer die hochleistungsumformtechnik zum erzeugen einer schlagartigen belastung oder verformung (arbeitsphase) - jeweils innerhalb weniger millisekunden oder innerhalb von bruchteilen davon - eines zu bearbeitenden und/oder zu verformenden koerpers und steuerung |
Also Published As
| Publication number | Publication date |
|---|---|
| IT8785501A0 (it) | 1987-01-02 |
| IT1210548B (it) | 1989-09-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN |
|
| AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): CH DE ES FR GB IT LI SE |
|
| 18W | Application withdrawn |
Withdrawal date: 19880629 |