US 2201244 A
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May 21, 1940. E, ROOT 2,201,244
SAFETY GUARD Filed May 26, 1957 r /ll llllllllllllll INVENTOR Edward Louis R0 Patented May 21, 1940 UNITED STATES PATENT OFFICE to Celluloid Corporation,
Jersey a corporation of New Application May 26, 1937, Serial No. 144,793
This invention relates to safety guards for automatic machines, and more particularly to a safety guard for use on an injection or extrusion molding machine.
Certain machines present a serious hazard to the operator because of the automatic nature of the same whereby certain parts thereof move in a prearranged time cycle. Injection molding machines for molding articles from thermoplastic material or the like are of this type. In these machines the dies are actuated in a predetermined time cycle. Frequently the material molded in the dies does not eject properly. It is then necessary for the operator to place his hand or hands between the dies to remove the molded articles. Although a switch for stopping the movement of the dies is, as a rule, readily accessible to the operator, through forgetfulness or carelessness he too often fails to throw the switch before placing his hands between the dies. As a result operators of these machines have been seriously injured.
It is an "object of this invention to provide in automatic machines an improved safety guard which will make it substantially impossible for the operator to be injured during the operation thereof.
Another object of this invention is the provision of a safety guard for an injection molding machine which is so designed that the operator has at all times full vision of the dies and the material between the dies when the die is in open position.
Other objects of this invention, together with certain details of construction and combinations of parts, will appear from the following detailed description and the appended claims.
In accordance with my invention, the safety guard, which is positioned over the die slide of the injection molding device. comprises a grilled cover through which the operator may at all times see the operation of the dies. This cover, which may be curved over the die slide, is equipped with means adapted, when the cover is raised, to stop the closing movement of the dies.
The arrangement is preferably such that upon the raising of the cover the closing movement of the dies is halted and they return to their full open position, in which position they remain until the cover is again lowered to operative, or safety, position. When the cover is lowered in operative position, the machine will start functioning immediately without further manipulation on the part of the operator, and will continue to do so until the cover or guard is again raised. A feature of the guard constructed in accordance with this invention is that the guard does not affect the cycle time or the speed at which the operator is required to work. He has a complete view of the dies at all times, yet is free to perform other details required by the machine.
In order further to illustrate my invention, reference is had to the accompanying drawing, wherein Figure 1 is a perspective view of a portion of an injection molding machine, showing the safety guard in open or inoperative position over the die slide of the machine,
Figure 2 is a view, on an enlarged scale, taken on line 2-2 in Figure 1, showing in full lines the position of the safety guard in closed or operative position and also the position and construction of the cam for operating the switch for arresting the movement of the dies,
Figure 3 is a rear elevational view of a portion of the safety guard as attached to the injection molding machine, and
Figure 4 is a wiring diagram for the operation of the molding dies.
Like reference numerals indicate like parts throughout the several views.
Referring to the drawing wherein the preferred embodiment of my invention is shown, reference numeral 4 generally indicates a portion of an extrusion or injection molding machine, i. e. that portion constituting the die slide. Suitably attached to side 5 of the molding machine is a bracket 6 on which is pivotally mounted,-as by means of hinges 1, a safety guard or cover 8 made of any suitable material. The cover is preferably curved and comprises ,a frame 9 in which are mounted a series of curved bars II. The bars are so spaced that the operator is able to see the parts .of the machine therethrough when the cover is closed, but is unable to put his hand between them. Each of the lateral edges of the frame 9 are provided with an apron I 2 to prevent the operator from having access to the parts of the machine from the sides. To expedite the raising and lowering of the cover there is provided a handle l3 suitably attached to the cover. A spring friction latch l4 affixed to the cover cooperates with side I5 to hold the cover in closed position.
Mounted on a bracket l6 fastened to side 5 of the molding machine by means of bolts I1 is an electric switch l8. An interlocking pilot valve may be used to perform the same function as the electric switch l8, except that a flow of fluid may be utilized to hydraulically operate the dies. A lever I9 having a roller 2! on a free end thereof is mounted on said electric switch. At one end of the cover there is attached a cam 22 by means of a bolt 23. When the cover is raised the cam 22 is adapted to act on roller 2| to depress lever IQ for the purpose of cutting off the power supply to the dies of the molding machine. In Figure 2 the dot-dash lines show the cover in fully raised position and the roller in its lowermost position.
Referring now to Figure 4, wherein the wiring diagram for operating the molding dies is shown, the reference numerals 24, 24 indicate the power line furnishing the current for operating the die opening and closing relays. The current passes through time switch 25 which operates the die opening relay 26 and time switch 21 which operates die closing relay 7.8. Reference numeral 29 indicates a switch which is operated by the opening and. closing of the safety guard through camlZ, roller 2| and lever IQ, and will be hereinafter referred to as the guard switch.
The operation of the device is as follows: Time cycle switches 25 and 2'! are so wired that when one is opened the other is closed, i. e. when die closing relay switch 2'! closes it automatically opens the die opening relay switch 25 and vice versa. 'When the safety guard or cover is closed over the die slide, the switches operate as stated.
:However, when the operator raises the safety guard for the purpose of removing something betweenthe dies, orfor any other reason, the cam 22 acts upon roller 2| to depress lever l9, thus opening the guard switch 29. The opening of :the guard switch 29 breaks the flow of current to die :closing relay switohZl. This causes the die closing operation to stop instantly and to return immediately to open position, thereby permitting the operatorsafely to work at the dies. The die halves cannot close since the power'to the die closing relay is shut oil. When the operator lowers a safety guard over the'die slide, theaction closes the guard switch 29, again allowing the time cycle switches 25 and 21 to function automatically in a predetermined cycle regulated by time clocks (not shown), .as is well understood in the art.
with a switch indicated on the wiring diagram by reference numeral 3 l ,Such a switch is adapted to shut on entirely the power being led to the machine. If used in the present invention it would, upon being opened, prevent current from operating the time switches. Therefore, if the die were on its closing motion when the switch 3! is opened, the die would instantly become locked in the position it was-at the moment it was cut off.
It is to be understood that the foregoing detailed description is merely given by way of illustration and that many variations may be made therein without department from the spirit of my invention.
Having described my invention, what I desire to secure by Letters Patent is:
1. In a molding machine, relatively movable dies, aguard positioned over said dies and mounted for vertical movement independently of said dies for preventing access to said dies, a source of power connected to' said diesfor moving at least one of said dies toward and away from the other of said dies and; relative-to said guard when the guard is in lowered position, means for controlling the source of power for determining the movement of saidniovable die, and means on said guard, operating when the guard is manually raised, for operating said controlling means to arrest the movement of the movable die toward the other die and to cause said movable die to return to open position.
2. In a molding machine, relatively movable dies, a guard positioned over said, dies and mounted for vertical movement independently of said dies for preventing access to said dies, a source of power connected to said dies for moving at least one of said dies toward and away from the other of said dies and relative to said guard when the guard is in lowered position, means for controlling the source of power for determining the movement of said movable die, and means on said guard, operating when the guard is manually raised, for operating the means for controlling the source of power to cut off the supply of power for moving the movable dies toward the other die and to apply said supply of power for moving the movable die away from the other die.
EDWARD LOUIS ROOT.