US3359598A - Safety means for hydraulic presses and the like - Google Patents

Description

26, 1967 H. R. BUCY 3,359,598

SAFETY MEANS FOR HYDRAULIC PRESSES AND THE LIKE Filed April 13, 1965 2 Sheets-Sheet l JNVEMra/e firmaueg.

H. R. BUCY Dec. 26, 1967 SAFETY MEANS FOR HYDRAULIC PRESSES AND THE LIKE Filed April 13, 1965 2 Sheets-Sheet 2 .r fiy ,B. 0534 I INVENTOR.

flrmemy United States Patent 3,359,598 SAFETY MEANS FOR HYDRAULIC PRESSES AND THE LIKE Harry R. Bucy, 550 N. Brighton St., Burbank, Calif. 91506 Filed Apr. 13, 1965, Ser. No. 447,809 16 Claims. (Cl. 1816) ABSTRACT OF THE DISCLOSURE A safety means for press type machines having stationary and moving die or mold carrying platens; said safety means comprising devices for interposing a bar between the platen, when they are separated to effect opening of the mold, and other devices for effecting the removal of the bar by means which, after first to removing the bar, initiates the operation of the machine after the bar has been removed or, in other words, in which the bar is removed as a prior incident only to the intentional actuation of the machine.

This invention relates to fluid pressure operated press mechanisms such as pressure die casting machines and injection molding machines for plastics as well as trimming presses and the like operated by fluid pressure cylinder and piston means and relates more particularly to a safety means serving to prevent unintended closing of the mold or dies or other instrumentalities.

By way of example, in the operation of certain machines of the type for which the invention is intended, a mold comprising a fixed or cover die half and a movable or ejector die half are held in juxtaposition under high clamping pressure while molten material is injected into the cavity formed by the two halves of the mold. When the mold is opened by the retraction of the ejector half, the operator must reach between the separated halves to remove the finished part, clean, and if necessary, lubricate the cavity surfaces. If any machine malfunction should occur causing the mold to close while he is thus occupied, the operator is likely to have his hand or arm caught between the mold halves, resulting in the loss of the member thus caught and at times, the injury thus caused has been known to be fatal. A similar hazard exists in all fluid pressure operated press mechanisms. A desire has often been expressed by members of Industrial Safety Commissions and like Governmental bodies for some sort of device which would prevent the unintended closure of molds of this character and which is not dependent on the machine operator. In other words, the desire is for a device which automatically will serve to prevent unintended closure of the halves of a mold by the expedient of automatically interposing a blocking member capable of preventing advance of the ejector half toward the cover half of the mold.

Other presently co-pending applications of the present applicant deal with situations deriving from breakage or other malfunction with the hydraulic cylinder which closes and opens the mold but those inventions do not cover the situation involving machines not equipped with that safety piston and piston rod nor the hazards deriving from such hazards as a leaking control valve or a broken operating toggle mechanism either of which might thus cause the ejector half of the mold to be moved unintentionally to closed position.

In the following specification reference will be limited to the use of the invention on a die casting machine, but from the teaching thus made available, the adaptation of the principles of the invention to other fluid pressure operated press mechanisms can readily be made by those skilled in the art, wherefore it is deemed unnecessary to go into details of every possible use of the invention. Ac-

cordingly,.the term mold as'employed in the specification and claims will be understood to be representation of all dies, molds and the like employed in press mechanisms to which the invention is applicable. Also, the term prior incident. will be understood to mean such an association of control devices that the machine cannot be caused to initiate a cycle of operation until the safety means has been intentionally moved out of the path of the moving component of the mold and in which such intentional movement of the safety means is the means which initiates the working cycle of the machine.

With these considerations in mind, it is an object of the present invention to provide a safety means for fluid pressure piston operated machines such as die casting machines, injection plastic molding machines or press mechanisms directly actuated by low pressure piston and cylinder means, which safety means normally interposes a rigid member between the relatively moving members of the machine when the mold is opened and which is effective thereby to prevent unintended movement of the ejector half of the mold toward the cover half to an extent suflicient to injure an operator in which safety means is so interlocked with the control means for the machine as to render the machine incapable of operation while the rigid member is so interposed.

Another object of the invention is to provide a safety device of the above character which is rendered inoperative to prevent closing of the mold only as an incident to intentional closing of the mold.

Still another object of the invention is to provide a device of the above character which is simple in design and capable of installation on any machine of the type for which it is intended regardless of whether the existing control for the machine which is subject to manipulation by the operator is pneumatic, hydraulic or electrical.

With the foregoing objects in view, together with such additional objects and advantages as may subsequently appear, the invention resides in the parts, and in the construction, combination and arrangement of parts described, by Way of example, in the following specification of certain presently preferred embodiments of the invention, reference being had to the accompanying drawings which form a part of said specification and in which drawings:

FIGS. 1a, 1b and 1c are side elevational views of a typical pressure die casting machine and showing diagrammatically the invention applied thereto With different modes of machine control and associated operating means for the closure preventing component and in which:

FIG. 1a shows a pneumatic pressure controlled, hydraulic pressure actuated system which is based on a manually operable air valve, the machine being shown in open position preliminary to being operated to effect closing of the mold,

FIG. 1b shows a control system which may be used with either hydraulic or pneumatic pressure and which includes a manually operated valve controlling the action of a pilot valve which controls the operating piston of the machine; the machine being shown with the mold closed preliminary to operating the control to open the mold, and

FIG. 1c shows an electrically controlled pneumatic or hydraulic operating system which is based on a manually operated electric switch, the controls being shown as they exist at the conclusion of a mold opening movement of the cylinder of the machine,

FIG. 2 is a greatly enlarged side elevational view of the mold closing preventing component of the device in the position occupied upon initiation of the mold opening portion of the operating cycle, other positions thereof being indicated in broken lines,

FIG. 2a is a fragmentary view of a portion of the device shown in FIG. 2 but showing the addition thereto of a micro-switch which is employed in the embodiments of the invention shown in FIGS. lb and 1c,

FIG. 3 is a sectional view taken on the staggered line 3--3 of FIG. 2,

FIG. 4 is a fragmentary sectional view taken on the line 44 of FIG. 2, and

FIG. is a further enlarged, fragmentary side elevational view, partly in section showing an alternative mode of use of the safety bar operating cylinder which may be employed in any of the embodiments of the invention.

Referring first to FIGS. 1a, 1b and 1c there is shown a die casting machine comprising a base A, a platen B for the cover half C of the mold rising from the base, a head member D rising from the base A and carrying a hydraulic cylinder E operably in which a piston E is reciprocable; said piston being connected by a piston rod F through an interposed toggle link mechanism F to the platen G and said platen being slidably mounted on the rods H extending between the platen B and head member D and said platen carrying the ejector half I of the mold.

The mold closure preventing component of the i1lustrated embodiments of the present invention is disclosed in detail in FIGS. 2 through 5 and, since it is substantially identical in all the embodiments of the invention, it will be described first. This component comprises a vertical bracket member I mounted closely above one of the tie rods H as, for example, on the platen B. Adjacent to the platen B, the bracket is provided with a slot extending therethrough parallel to the direction of movement of the ejector half of the mold and a horizontal pivot pin 2 extending across said slot serves as a pivotal mounting for one end of a supporting arm 3 for the stop bar to be presently described. At its upper end, the bracket member 1 carries a short horizontal arm 4 extending toward the ejector half of the mold and a pivot pin 5 extending through said distal end ofsaid arm parallel to the pivot pin 2, pivotally secures the forked end of the head end 6 of a pneumatic cylinder 7 to said arm 4. The opposite end of the cylinder 7 constitutes a combined head and guide means 8 for a piston rod 9 which, within the cylinder 7, is connected to a piston 10 and the other end of said piston rod carries a head element 11 which is pivotally secured to ear means 12 on the distal end of the arm 3 by a pin 12'. The cylinder head member '8 is provided with a port 13 which is connected by a passage 14 to the interior of the cylinder at the side of the piston -10 which is adjacent to said head member 8. A nipple 15 alfords connection between the port 13 and one end of a hose 16, the other end of which is connected to control means to be presently described.

The arm Scarries a depending bracket element 17 which, in turn, carries a sleeve member 18 extending parallel to the arm 3. Removably' disposed in this sleeve is the stop bar element 19 secured the-rein by a set screw 20. In FIGS. 1a and 10, this bar is shown disposed between the opposed faces. of the support B and platen G the bar being slightly shorter than the distance between said opposedfacs for a reason to be presently referred to. It will be obvious that when the stop bar is in this position, any malfunction in the hydraulic cylinder and piston cannot cause the ejector half to be brought into contact with the cover half.

Referring now to FIG. 1a, the control means for the hydraulic cylinder E and the piston E and the piston rod F comprises the reversible valve J and this valve, in turn, is operated by a double acting pneumatic cylinder 21 containing a piston carried by a piston rod 22, the piston rod being connected by a pivot pin 23 to the operating arm I of the valve, I here shown as a rotary disk type valve, but any suitable reversing valve, whether rotary, spool, poppet or any other form, can of course be employed. The actuating means, for the piston and piston rod 22 comprises the manually operable, reversing pneumatic valve 24 which is connected by lines 25 and 26 to the opposite ends of the cylinder 21. The inlet port of the valve 24 is connected to a source of compressed air by a line 27 and a line 28 serves as the exhaust from said valve. Again, while a disk type valve is shown, any suitable form of reversing valve may be employed. The said other end of the hose 16 is connected by a T-fitting 29 to the line 25.

In describing the operation of the device shown in this figure, it will be assumed that the valve 24 has been moved to the position shown in FIG. 1a and that the parts of the machine affected thereby have completed their respective movements in consequence thereof. Thus compressed air has been conducted through line 26 to cylinder 21 moving piston 22 to the left with consequent counterclockwise movement of the valve member of valve J and resultant application of hydraulic fluid in cylinder E to move the piston thereof to the right, opening the mold as shown. Movement of the valve 24 in the opposite direction connects the line 25 to the air pressure source represented by line 27 moving piston 22 to the right and causing valve J to be moved to connect the outer or right hand end of cylinder E to hydraulic pressure with resultant movement of piston F thereof to the left and closing of the mold. The imposition of pressure in line 25 has simultaneously imposed pressure through hose 16 to the piston rod end of cylinder 7 and has caused the piston 10 and piston rod 9 to lift the arm 3 and the stop bar 19 carried thereby upwardly out of the path of the platen G as it is caused to be advanced by the piston E and its piston rod, said position being represented by the upper broken line position in FIG. 2. Movement of the valve 24 back to the position shown in FIG. 1a disconnects line 25 from the pressure source and opens it to atmosphere allowing the bar to drop to the full line position of FIG. 2 until the retreating platen allows it to drop between the platens in the lower dotted line position to the extent permitted by engagement of the piston 10 with the cylinder head 8 thus preventing closing of the mold as shown in FIG. 2.

It will be understod that while this operation of the device has been described in a sequential order, in actual usage the entire movement of the stop bar to its upward position and the closing of the mold takes place very quickly, the entire time for the closure of the mold not infrequently being of the order of less than two seconds. It will be noted that the pressure Will be simultaneously applied to the pistons 10 and 22, but since the load imposed on the piston 10 incident to lifting the bar is less than the load imposed on the piston 22 by the frictional resistance of the valve J, the piston 10 will have lifted the bar before the valve 1 will have been operated to cause the mold closing movement of the machine. However, even if the resistances were of equal magnitude, the fact that the piston 22- is required to partake of some travel movement before the valve J is opened, would result in the removal of the bar before the initiation of the mold closing movement.

The head member or end 6 of the cylinder 7 is provided with a port 30 which is normally closed by a plug screw 31. When the, device is actuated to lift the arm 3 and the stop bar 19, the air trapped between the head 6 and the piston 10 is compressed and acts as a spring which resists the lifting of the arm 3 and stop bar incident to retraction of the piston and piston rod so that when the valve 24 is moved to a position to retract the piston of cylinder 21 through air pressure applied through line 26, the side of the cylinder connected by the hose 16 to line 25 will be connected to the exhaust, whereupon, the compressed air in the head end of cylinder 7 will assist in moving the arm downwardly until the stop bar 19 rests on top of the retreating platen as shown in full lines in FIG. 2. Obviously, before complete retraction of the platen, the stop bar will drop into the position shown in FIGS. 1a and 1c and the lower broken line position shown in FIG. 2, further movement being terminated by engagement of the piston with the head member 8, finer degrees of adjustment being achieved by the threaded engagement of the piston rod 9 with head element 11.

Alternatively, as shown in FIG. 5, the plug 31 may be left out and the weight of the stop bar being permitted to cause it to drop first to the position of repose shown in FIG. 2 and thence to the safety position above referred to when the platen has been sufliciently retracted.

The reason for mounting the stop bar 19 in the sleeve 20 is to make it possible to quickly interchange the stop bars for others of different lengths to accommodate different mold heights and resultant different spacing of the platens when the molds are open so that when one end of the stop bar is dropped between the platens, the ends of the stop bar will be disposed with the desired minimum clearance therebetween.

-FIG. 1b shows the application of the invention to a die casting machine having a manually controlled fluid pressure responsive cylinder and piston means E for closing and opening the mold, such fluid pressure being either hydraulic or pneumatic. In this embodiment, the present invention is so incorporated in the line which supplies fluid pressure to effect mold closing movement that introduction of operating pressure into that line must first effect the actuation of the safety bar lifting means before the operating pressure is imposed on the piston of the cylinder E to effect closing of the mold. In the system shown in this figure, a manually operated reversing valve 32 (here schematically shown as a disk type valve) has an inlet port connected to a supply of hydraulic fluid under pressure by a line 33 and an exhaust port connected to a return line 34 leading to a reservoir (not shown). A line 35 connects one port of the reversing valve to the outer end of the cylinder E to supply fluid to eflect the working or mold closing stroke of the piston, said line also being connected to an air line controlling valve 36 and being interrupted adjacent the connection to the cylinder E by a solenoid controlled check valve 37 which is a standard article of commerce, the construction of said valve being such as will allow fluid to pass therethrough freely from the cylinder E to the valve 32 but which will allow fluid to pass therethrough from the valve 32 into the cylinder E only when the solenoid component thereof is energized by means presently to be described. The opposite end of this cylinder E is connected by line 38 with the appropriate port of the reversing valve 32.

The valve 36 is a standard article of commerce but will be described in the manner in which it is employed in the present invention. The hydraulic port 39 thereof which is connected to the hydraulic cylinder supply line 35 communicates with the chamber 40 within the valve body and one side of said chamber is formed by a reciprocable piston 41. The valve body is provided with a first air port connected to a source of supply of compressed air by line 42, a second port connected to the hose 16 and thus to the cylinder 7 by a line 43 and a third port connected to an exhaust line 44. Within the body is a reciprocable valve member 45. carrying the piston 41 and which is biased by a spring 46 to oppose hydraulic pressure imposed on the piston. When no pressure exists in the chamber 40, this valve member is moved to maintain the lines 43 and 44 in communication with each other. The imposition of line hydraulic pressure in the chamber 40 causes the piston 41 to move the valve means against the bias of the spring 46 to disconnect comunication between the lines 43 and 44 and to interconnect the lines 42 and 43- thus subjecting the cylinder 7 to air line pressure.

The solenoid of valve 37 is connected with a suitable source of energy by leads 47 and 48, the lead 48 extend ing to one side of a normally open micro-switch 50 mounted on the vertical bracket 1 closely adjacent to the pivot pin 2 and having a feeler or operating plunger portion 51 positioned for contact by the initial upward movement of the arm 3 as best shown in FIG. 2a and the other side of terminal of said switch is connected by lead 49 to the source of energy to complete the circuit.

When the valve 32 is moved to the position shown in FIG. 1b, hydraulic pressure is introduced into the line 35 but since the valve 37 is normally closed, this fluid is prevented from reaching the outer end of the cylinder E, however, the pressure actuates the valve 36 to introduce air pressure to the safety bar operating cylinder with resultant lifting of the safety bar out of the path of the platen G. This closes the switch 50 energizing the solenoid valve 37 and allowing hydraulic pressure then to enter the cylinder and move the piston to the left with resulting closing of the mold as shown. Reversal of the valve 32 imposes fluid pressure through the line 38 moving the piston to the right and with consequent expulsion of fluid through the free flow portion of the valve 37 to the valve 32 and thence to the reservoir of the hydraulic system. The lesser pressure in the line 35 allows the spring 46 to move the valve member 45 to a point connecting lines 43 and 44 and thus establishing communication of the cylinder 7 with the exhaust port and atmosphere allowing the trapped compressed air therein, or if the port 30 is left open, the weight of the stop bar and arm 3 to effect the dropping of the stop bar against the retreating platen and eventual dropping into blocking position as soon as the platen is retracted beyond the end of the stop bar as shown in FIGS. 2, la and 10. As in the first described embodiment, these sequential steps take place so quickly as to be almost simultaneously.

While this embodiment of the invention comprises a hydraulically operated machine in which the hydraulic system controls the application of the pneumatic pressure to the means which lifts the stop or safety bar with resultant opening of a valve to allow the hydraulic pressure to close the mold, it will be obvious that with suitable modification of the valve 36, pneumatic operating pressure might be employed in place of the hydraulic pressure means.

FIG. 10 shows the principles of the invention applied to a control system in which the manually operated means comprises an electric switch to be later described, a first solenoid operated valve 522 for controlling the supply of operating fluid to the cylinder E, and a second solenoid operated valve 53 for controlling the supply of compressed air to the stop bar operating cylinder 7. This embodiment of the invention eliminates the solenoid operated check valve 37 employed in the embodiment shown in FIG. lb. The valves 52 and 53 are standard articles of commerce and are hence shown only schematically.

The valve 52 is a slide or spool valve having an inlet port connected to a pressure supply line 54, an outlet port connected to a return line 55, a first cylinder port connected by a line 56 to the outer end of the cylinder E and a second cylinder port connected by a line 57 extending to the opposite end of the cylinder E. The spool component of the valve is moved axially in the valve body 58 by solenoid coils 59 and 60 carried by the opposite ends of the valve body.

The valve 53 may be assumed to be substantially the same as the valve 36 except for the substitution of the solenoid 61 for the piston 41, for operating the valve member in opposition to the biasing spring.

In addition to being connected to the solenoids heretofore described, this embodiment of the invention additionally is connected to the manually operated switch 62 which, like the solenoid valve 52,'is standard equipment on the press mechanism, the pole 62 thereof being connected for double throw operation between terminal 63 connected to solenoid 59 by a lead 65 and terminal 64 connected by a lead 66 to one side of the micro-switch 50, the other side of said micro-switch being connected by a lead 67 to one side of the solenoid 60 of the valve '52, it being noted that when the switch pole is moved to connect the power lead 63' to the terminal 63, as shown, the solenoid 59 is energized to move the valve spool to the right with resultant delivery of pressure fluid through line 57 to the left hand or inner end of the cylinder E and that when the switch pole 62' is moved to connect lead 63 to the terminal 64, the solenoid 60 Will not be energized to move the valve spool to the left With resultant delivery of pressure fluid to the outer end of the cylinder through line 56 until the normally open microswitch 50 will have been closed by lifting of the stop bar through pressure applied to the cylinder 7 by reason of opening of valve 53. Thus the mold can not be closed until the stop barhas first been removed. Terminal 64 is also connected by a lead 68 to one side of solenoid 61 in valve 53. The other sides of all three solenoids are suitably connected to a common power lead 69 to complete the various circuits.

In FIG. 1c, the machine and system are shown at the time that opening of the mold has been completed. Solenoid 59 had been energized to cause valve 52 to admit pressure fluid through line 57 to the inner or left hand end of cylinder E, the mold is completely open and the stop bar has dropped into safety position. Movement of switch 62 to cause pole 62 to contact terminal 64 will effect energization of solenoid 61 of valve 53. Energization of solenoid 61 will actuate valve 53 to admit compressed air therethrough to stop bar operating cylinder 7, lifting the stop bar and closing micro-switch 50. Closure of this switch completes the circuit through leads 66 and 67 to solenoid 60 with resultant supply of pressure fluid to the outer end of cylinder E and consequent closure of the mold.

Movement of switch 62 to cause the pole 62' thereof to contact terminal 63 will simultaneously open the circuit through solenoid 61 allowing the spring in valve 53 to move the valve member thereof to connect the interior of cylinder 7 with atmosphere allowing the stop bar to first drop on the retreating platen and then drop in front of it asthe platen reaches substantially maximum retraction. By reason of the micro-switch being interposed in the operating circuit for the valve operating solenoid 60, pressure fluid for closing the mold cannot be supplied to the cylinder until and unless the stop bar has been moved completely clear of the path of the advancing platen. As in the other embodiment, it will be appreciated that the various movements of the control system occur so quickly after operation of the switch 62 as to be almost simultaneous. As in the case of the embodiment shown in FIG. lb the fluid pressure may, in some cases, be pneumatic rather than hydraulic for operating either or both piston elements.

Many machines for which the present invention is intended are provided with semi-automatic controls which, for'example, are like that shown in FIG. 10 with the addition of a timer means so arranged that when the switch 62 .is manually operated to initiate a closing stroke the machine closes the mold or performs such other function as may be required and at the completion of a predetermined interval the switch 62 is automatically moved to the opposite position. Such machines normally have a lead extending from a switch terminal to the solenoid which effects the working stroke as, in the present instance, the solenoid 60. In adapting the machine to the improved control on safety means of the present invention it would be necessary only to interpose the micro-switch 50 in that lead and connect one side of the valve solenoid 61 to terminal 63.

The various embodiments of the invention above disclosed relate to a die casting machine. It will be obvious to those skilled in the art to which the invention appertains that the principles of the invention can be equally well applied to injection molding machines for plastics which, like die casting machines, involve the closure of molds by imposed fluid pressure and the introduction of molten material into the mold cavities under high pressure and in which machines the danger of unintended closure of the molds While an operator is reaching between the mold halves has heretofore been deemed to be a normal risk of the operation of such machines. Obviously, also, the principles of the invention can be equally Well applied to any press mechanism actuated by a fluid pressure responsive piston means. The illustrated embodiments of the present invention provide safety means for die casting machines and the plastic injection molding machines employing separable die or mold devices which virtually eliminates that very great risk; said safety means being simple in construction and automatically effective to interpose a stop member capable of preventing unintended closing of a mold and thus to eliminate the ever present danger of maiming an operator by such unintended closure. Further, as shown in the various embodiments. of the invention, the principles of the invention are not limited to any one specific form of machine control but can be applied to any machine regardless of whether the control of such machine be pneumatic, hydraulic or electrical, all of such manual controls being known and used on machines of the character for which the invention is intended. Still further, while the illustrated embodiments of the invention relate to a machine having separable molds, the principles of the invention are not limited to molding machines and may be employed as well on machines employing dies or other tools in which one component is moved toward and away from another component by fluid pressure means,

While for purposes of illustration, the invention has been illustrated as applied to a die casting machine subject to full manual operation it is recognized that the more modern die casting and injection molding machines are semi-automatic in that upon manual actuation of the switch to effect mold closing, timing devices which form a part of the control system effect the sequential machine operations of filling the mold, holding the mold closed for a predetermined time and then opening the mold and coming to a stop. Even with such controls it will be evident that the safety bar operating means may suitably be connected for operation by whatever means is employed to control the main fluid pressure means. Usually, plastic injection molding machines are provided with a manually opened door through which access to the opened mold is had and which has a switch associated therewith so arranged that while the door is opened, the machine is normally incapable of causing the mold to be closed. This is no protection against a malfunction of the control system or the power system not involving the switch which is opened by opening that door. With the device of the present invention installed on the machine, even malfunctions not capable of being prevented by the access door described can be prevented.

This aspect of the invention has been discovered to have another important safety factor. There have been instances when static or stray currents in the automatic control devices have caused an unintended reversal of the operating switch or of means operated thereby.

The protection afforded by the operator by the positioning of the stop or safety bar between the opened dies or mold halves has been treated at length above. When and if a malfunction of the control means should have the same effect as the operation of the switch which initiates movement of the movable mold or die component toward the stationary component, the stop bar, being always in the line of vision of the operator when he is reaching between the dies, by its movement away from its safety position gives the operator visual warning that the press is about to close. This gives him time to get his hand or arm out of the way of the advancing die or mold half and possibly even time to operate a stop switch to stop the machine. Without such visual warning in advance of the actual closing of the die or mold, it is probable that the mold or die half will be advancing before he is aware of the malfunction and is caught and maimed.

' This capacity for giving visual warning of malfunction has another advantage. Knowing (a) that the mold or die can not close so long as the safety bar is between the halves and (b) that even when the bar is thus positioned the die or mold can not be closed by a malfunction without the bar being first lifted and thus giving him warning, he is spared the mental fatigue of always being on the alert for such unexpected happenings and can reach between the opened mold or dies with assurance of being safe in doing so. In actual tests, this factor has been found to contribute materially to the productiveness of operators.

Having the foregoing considerations in mind as the invention is shown to be advantageously applicable not only to machines subject to full manual operation or to the so-called semi-automatic operation in whichthe machine is manually'caused to start each cycle of operation, but also to full automatic machines which are manually stopped at will after having executed a plurality of operating cycles,v the references to manual control means or means under control of the operator as employed in the claims will be understood to embrace all three types of machines above mentioned. Moreover, while certain presently preferred embodiments of the invention have been disclosed by way of example, wherefore, it is not to be inferred therefrom that the invention is limited to the precise details of construction so disclosed, and it will be understood that the invention includes as well, all such changes and modifications in the parts, and in the construction, combination and arrange ment of parts as shall come within the purview of the appended claims.

I claim:

1. A safety means for preventing unintended closure of a mold in a fluid pressure actuated press mechanism of the type comprising a frame structure and fixed and movable platen means for supporting the halves of a mold or die associated with said frame structure fluid pressure means on the frame structure operative to move the movable platen means toward and away from the fixed platen means and control means for starting and stopping actuation of the fluid pressure means; said safety means being mounted on said press mechanism and comprising a bar of slightly less length than the distance between the opposed surfaces of said movable and fixed platen means when separated to the greatest extent and normally positioned endwise between the separated platen means, a supporting bracket on which said bar is mounted for movement between said normal position and another position out of the path of movement of the movable platen means toward the fixed platen means, and power means interconnected with the press mechanism control means and operatively connected to said bar effective automatically to move said bar to said other position as a prior incident only to intended movement of the movable platen means toward the fixed platen means.

2. A safety means as claimed in claim 1 in which said supporting bracket is mounted out of the path of movement of the movable platen means, in which said power means is arranged to remove said bar from said normal position when energized, and in which said power means is resiliently operative to urge said bar toward said normal position as the movable platen means of the press mechanism is caused to move away from the fixed platen means.

3. A safety means as claimed in claim 1 in which said supporting bracket is mounted out of the path of movement of the movable platen means, in which said power means, when energized, is arranged to remove said bar from said normal position, and in which said power means is disabled and said bar is allowed to return to its said normal position by its own weight as the movable platen means of the press mechanism is caused to move away from the fixed platen means.

4. A safety means for preventing unintended closure of a mold in a hydraulic press mechanism of the type comprising a frame structure having a fixed platen provided with a surface on which one component of the mold is mounted, and a hydraulic cylinder and piston connected to and reciprocating a movable platen carrying the other mold component into and out of mold closing engagement with the first named mold component and control means operated by the operator of the machine for actuating the cylinder and piston to effect opening and closing of the mold as desired; said safety means being mounted on the press mechanism and comprising a bar of slightly less length than the distance between the mold carrying surfaces of the platens when separated to the greatest extent and normally positioned endwise between the platens when so separated, a supporting bracket on which said bar is mounted for movement between said normal position and another position out of the path of movement of the movableplaten, and power means interconnected with the press mechanism control means and operatively connected to operate said bar to move said bar only to said other position as a prior incident to mold closing operation of the press mechanism intentionally initiated by the press mechanism control means.

5. A safety means as claimed in claim 4 in which said supporting bracket is mounted out of the path of movement of the mold carrying platen of the press mechanism, in which said power means is arranged to move said bar to said other position when energized, and in which said power means is resiliently operative to urge said bar toward said normal position as the mold carrying platens of the press mechanism are caused to separate.

6. A safety means as claimed in claim 4 in which said supporting bracket is mounted above the path of movement of the movable platens of the press mechanism, in which said power means is arranged to lift said bar to said other position when energized, and in which said power means is disabled and said bar is allowed to fall into its said normal position by its own weight as the platens of the press mechanism are caused to separate.

7. A safety means as claimed in claim 4 in which movement of the movable platen is effected by a hydraulic cylinder and piston controlled by flow reversing valve means and fluid conduits extending between said hydraulic valve means and the opposite ends of said hydraulic cylinder, in which the one of said conduits through which fluid is supplied from said reversing valve to said cylinder to cause mold closing operation of the press mechanism by the piston of said hydraulic cylinder is provided with a normally closed valve to prevent fluid flow therethrough in a direction to effect mold closing movement, and in which means responsive to movement of said safety means to its said other position is operatively connected to effect opening of said normally closed valve with resultant fluid flow to said cylinder and closing of the mold only after said safety means is moved to the said other position.

8. A safety means as claimed in claim 4 additionally including a reversible, pneumatic pressure responsive motor means including an actuated element, a manually operated reversing valve operatively connected between said motor means and a source of pneumatic pressure, a second reversing valve operatively connected to opposite ends of said hydraulic cylinder and piston for effecting mold opening and closing movements of the movable platen and including a movable valve element operatively connected to said actuated element of said motor means, and pneumatic pressure conduit means connected to operate said bar moving power means when said manually operated valve is moved to cause said second reversing valve to effect movement of the movable platen toward the fixed platen with resultant movement of said safety means out of said normal position only incident to closing of the mold.

9. A safety means as claimed in claim 4 in which the direction of movement of said press mechanism cylinder and piston and consequent movement of the movable platen toward and away from the fixed platen is controlled by manually operated hydraulic valve means, and in which said power means for removing said bar from its said normal position comprises a pneumatic pressure responsive cylinder and piston connected to a source of pneumatic pressure through valve means responsive to hydraulic pressure in a conduit downstream of said manually operated hydraulic valve means through which fluid is supplied to eifect movement of the movable platen toward the fixed platen.

10. A safety means as claimed in claim 4 in which the press mechanism control includes electric switch means and .an electrically actuated reversing valve operatively interposed between a source of hydraulic pressure and said hydraulic cylinder and piston and controlled by electrical connections with said switch, in which a normally closed electrically controlled valve is interposed between a source of pneumatic pressure and said power means of said safety means, and in which electrical connections extend between said switch and said last named valve operative to open said valve for energization of said power means and movement of said bar of said safety means out of said normal position as an incident to operation of said switch to cause movement of the movable platen toward the fixed platen of the press mechanism.

11. A safety means as claimed in claim 4 in which said supporting bracket member is disposed above the mold component carrying surface of one of the press mechanism platens, in whicha bar supporting arm is pivotally connected to said bracket member adjacent to the press frame structure with the free end of said arm extending toward the other of the mold component carrying platens and having means carrying said bar spaced from said arm, and in which said power means comprises a pressure responsive cylinder and piston assembly interconnecting said arm and said bracket member .at points thereon remote from said, pivotal, connection and operative in response to pressure induced retraction of said assembly to lift said arm and said bar moving said bar from said normal position out of the path of movement of the movable platen of the press mechanism.

12. A safety means; as claimed in claim 4 in which said bar is detachably carried by an arm. havingv one end thereof pivotally connected to said supporting bracket, and in which said power means reacts between said supporting bracket and a point adjacent the opposite end of said arm.

13. A safety means as claimed in claim 4 in Which said bar is carried by an arm having one end thereof pivotally mounted on said supporting bracket, and in which said bar is removably mounted on said arm.

14. A safety means as claimed in claim 4 in which said power means comprises a piston and cylinder assembly and in which the engagement of the piston of said assembly with an end member of said assembly affords a stop means determining said normal position of said bar.

15. A safety means as claimed in claim 5 in which said bar is connected to said bracket for pivotal movement into and out of said normal position, in which said power means com-prises a cylinder and piston assembly including a piston rod slidable in a sealed end member constituting one end of the cylinder, in which the opposite end of said cylinder is sealed, .and in which said cylinder adjacent to said one end thereof is provided with a connection affording communication with a source of fluid pressure.

16. A safety means as claimed in claim 6 in which said bar is connected to said bracket for pivotal movement into and out of said normal position, in which said power means comprises a cylinder and piston assembly including a piston rod slidable in a sealed end member constituting one end of the cylinder, in which the opposite end of said cylinder is open to atmosphere, and in which said cylinder adjacent to said one end thereof is provided with a connection affording communication with a source of fluid pressure.

References Cited UNITED STATES PATENTS 2,584,534 2/ 1952 Barnhardtson. 2,946,277 7/1960 Archer -53 2,990,578 7/1961 Adair et al.

WILBUR L. MCBAY, Primary Examiner.

Claims (1)

1. A SAFETY MEANS FOR PREVENTING UNINTENDED CLOSURE OF A MOLD IN A FLUID PRESSURE ACTUATED PRESS MECHANISM OF THE TYPE COMPRISING A FRAME STRUCTURE AND FIXED AND MOVABLE PLATEN MEANS FOR SUPPORTING THE HALVES OF A MOLD OR DIE ASSOCIATED WITH SAID FRAME STRUCTURE FLUID PRESSURE MEANS ON THE FRAME STRUCTURE OPERATIVE TO MOVE HE MOVABLE PLATEN MEANS TOWARD AND AWAY FROM THE FIXED PLATEN MEANS AND CONTROL MEANS FOR STARTING AND STOPPING ACTUATION OF THE FLUID PRESSURE MEANS; SAID SAFETY MEANS BEING MOUNTED ON SAID PRESS MECHANISM AND COMPRISING A BAR OF SLIGHTLY LESS LENGTH THAN THE DISTANCE BETWEEN THE OPPOSED SURFACES OF SAID MOVABLE AND FIXED PLATEN MEANS WHEN SEPARATED TO THE GREATEST EXTENT AND NORMALLY POSITIONED ENDWISE BETWEEN THE SEPARATED PLATEN MEANS, A SUPPORTING BRACKET ON WHICH SAID BAR IS MOUNTED FOR MOVEMENT BETWEEN SAID NORMAL POSITION AND ANOTHER POSITION OUT OF THE PATH OF MOVEMENT OF THE MOVABLE PLATEN MEANS TOWARD THE FIXED PLATEN MEANS, AND POWER MEANS INTERCONNECTED WITH THE PRESS MECHANISM CONTROL MEANS AND OPERATIVELY CONNECTED TO SAID BAR EFFECTIVE AUTOMATICALLY TO MOVE SAID BAR TO SAID OTHER POSITION AS A PRIOR INCIDENT ONLY TO INTENDED MOVEMENT OF THE MOVABLE PLATEN MEANS TOWARD THE FIXED PLATEN MEANS.

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