US3718415A - Mechanical and pneumatic knockout pin - Google Patents

Abstract

KNOCKOUT PINS TO EJECT MOLDED ARTICLES FROM DIES AS THE SAME OPENS, SAID PINS BEING MECHANICALLY ACTUATED BY CAMS UNDER PNEUMATIC INFLUENCE TO A CERTAIN PREDETERMINED DEGREE, AND THEREAFTER FURTHER ACTUATED PNEUMATICALLY ONLY, TO A GREATER EXTENT.

Description

Feb. 27, 1973 5 FELlCE 3,718,415

MECHANICAL AND PNEUMATIC KNOCKOUT PIN Filed June 1, 1971 2 Sheets-Sheet 1 INVENTOR AMEDlo PDEFELICE ATTORNEY Feb. 27, 1973 A. P. DE FELICE 3,718,415

MECHANICAL AND PNEUMATIC KNOCKOUT PIN Filed June 1, 1971 2 Sheets-Sheet 2 INV EN TOR.

flm'edt a P De/ell'c'c BY Attorney 3,718,415 MECHANICAL AND PNEUMATIC v KNOCKOUT PIN Amedio P. De Felice, 251 Florence St, Leominster, Mass. 01453 Filed June 1, 1971, Ser. No. 148,817

Int. Cl. B29c 7/00 US. Cl. 425-444 15 Claims ABSTRACT .OF THE DISCLOSURE Knockout pins to eject molded articles from dies as the same opens, said pins being mechanically actuated by cams under pneumatic influence to a certain predetermined degree, and thereafter further actuated pneumatically only, to a greater extent.

BACKGROUND OF THE INVENTION 7 Reference is made to my copending application for United States Letters Patent filed Mar. 24, 1971, entitled Air Actuated Knockout Pin.

Although the air actuated knockout pins solved problems present in the art, it has nevertheless been found that in certain instances some problems still remain, and it is therefore an object of the present invention to provide knockout pins which are first actuated positively, i.e., mechanically moved part way, and then immediately thereafter further moved pneumatically to the full extent.

For example, it is sometimes advantageous to utilize a hot runner on the front half of the die and in this case it is necessary to break the gates before ejecting the articles. It is not usually possible to break the gates merely with air actuated pins, but by the use of the present invention, the pins can break the gates on the mechanically actuated interval, where the pins are positioned to contact the articles adjacent the gate, and then the articles are ejected from their cavities upon the ensuing interval wherein the pins are projected to a greater degree by air alone. 1

SUMMARY OF THE INVENTION A knockout pin for an injection molding die suitably situated in a part of the mold for ejecting the molded article as the die parts open, said pin having a head located in a cylinder with a cup-shaped sleeve surrounding said head and axially movable in said cylinder against a spring, and a head and sleeve actuator, e.g., a movable ball or the like located in an opening in the wallof a plate having an elongated passage with a rod therein and a relatively inclined cam on the rod, with the ball in contact therewith, the ball normally being at the lowest point of the cam the head and sleeve being fully retracted, said rod being actuated at the proper time by timed pneumatic means as the die opens to move the cam to a position wherein the ball is forced against the bottom of the sleeve, thereby pushing the knockout pin, against the action of the spring, to project theend thereof to a predetermined degree under a fully mechanical influence, said rod being provided with passages for access of the air to the sleeve thereby projecting the knockout pin a further distance simply and solely by pneumatic action.

This invention therefore provides a combination actuation of the knockout pin which is initially fully mechanical and positive in action and then terminating in a pneumatic final actuation, thereby having the advantages derived in my aforesaid application for patent, but at the same time adding an initial positive mechanical action, avoiding any kind of sticking in the initial operation of the knockout pin and providing for breaking oil of the article at the gate just prior to ejection.

3,718,415 Patented Feb. 27, 1973 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view which illustrates the knockout pins in normal retracted condition;

'FIG. 2 is a similar view which illustrates the knockout pins projected to their fullest extent by mechanical means;

FIG. 3 is again a similar view illustrating the further projection of a knockout pin under the influence of pneumatic means; and

FIGS. 4, 5, and 6 are views similar to FIGS. 1, 2,

'and 3 respectively, but showing a modification of the cams.

PREFERRED EMBODIMENT OF THE INVENTION The reference numeral 10 indicates a die part in which there are provided axially movable knockout pins such as at 12, 12. These knockout pins are each provided with heads 14, 14 located in a cylindrical cup- like sleeve 16, 16 having a closed end :18, 18. Each sleeve and pin is provided with a spring 20, 20, when needed, to normally locate the pin in retracted position as shown in FIG. 1 in cylindrical cavities 22. The springs however are capable of yielding to allow the projection of the knockout pins for their intended function by forces acting on the closed ends 18 of the sleeves. Where the pins are upright, they need no spring retraction means but fall back by gravity.

Each cylinder 22 has an open end at 24 as shown by which the parts may be assembled, after which plate 26 is arranged in flatwise relationship with respect to the part 10 and in fixed relation thereto, covering the open cylinders 22.

The plate 26 is provided with openings at 28, 28 each of which is on a slant as shown and each of which opens into a cylindrical elongated bore 30 in the member 26.

I I The openings 28 are smaller than the open ends of the 34 held in place as by a plug 36. Rod 32 has a series of inclined or tapered spaced cams as at 3 8, 38, each of which has a wide or high end 40 and a thin or low end 42, 42, and in FIGS. 1-3, these cams as shown may be likened to conical spear or arrowheads. The higher cam ends 40 fit bore 32.

There is a pneumatic fitting 44 which isconnected at the opposite end of the elongated bore 30 from plug 36 and this is connected to a source of air under pressure controlled by an automatic valve, not shown, which operates in correct timed relation as the die parts open. in a manner which will be clear to those skilled in the art.

The higher end 40 of the cam next to the fitting 44 is provided with an air receiving chamber 46 and an air passage 48 which may be e.g., spiral, leads from this chamber into an area therein just prior to the start-down of the inclination of cams 38.

At each thin (low) portion 42 of each cam as seen in FIG. 1, there is provided a loose ball 50 which has a diameter allowing the same to pass through openings 28, but does not disturb cup-shaped sleeves 18 when rod 32 is retracted. However, any motion to the right of the rod 32 will cam the balls upwardly against the bottoms of the cup-shaped sleeves 18 and positively push them upwardly to position the knockout pins as shown in FIG. 2.

In FIG. 2 therefore the balls have pushed the rods upwardly to their fullest extent under the capability of the mechanical means, i.e., the cams, this having been achieved by moving rod 32 by air. It will be noted however that the air passage 48 is now in open communication with the opening 28 for the first ball, i.e., the one nearest the air fixture 44, and at the same time this air also is open to the second and third balls. This air then gives a secondary push on the bottom of all of the cup-shaped sleeves moving them and the knockout pins upwardly to the FIG. 3 position, see the arrow in FIG. 3.

It will therefore be seen that there is initially a positive mechanical actuation of the knockout pins to a predetermined degree, and that once this has taken place the air is available to push the pins pneumatically to their full extent, FIG. 3.

Should bore 30 and rod 32 be vertical, with the fixture 44 at the bottom, the spring 34 would not be needed, as the rod 32 would drop by gravity when the air shuts off at the proper interval.

Assuming that articles are formed in the front part of the die, e.g., by using a hot runner in the front half, and the pins 12 are located to enter the cavity closely adjacent the usual gate, the initial positive thrust of the pins will not only start to move the respective article out of its cavity but will break the gate at its juncture with the article (since the runner remains with the die half) and then the pneumatic action in further projecting the pin fully ejects the article.

FIGS. 4, '5, and 6 show a modified cam construction but otherwise the operation is the same as before. By

preventing cam rod 32 from rotating by a longitudinal fixed end pin 52 received in an eccentric bore 54, the cams may be milled off chordally as at 56, 56, still providing a thick or wide end 40' and a thin end 42, and therefore the cams need not be conical as shown in FIGS. 1-3. Once the cam rod has been moved from the FIG. 4 position to the FIG. 5 position, the air passage 48' is free to supply pressure to all the sleeves 16', and the two step motion of the knockour pins 12 is achieved as before.

The balls 50', fitting 44, springs 20, and cylinders 22', as well as less important parts are the same as in FIGS. 1-3.

I claim:

1. In a molding machine having a die part, a knockout pin slidably mounted in said die part, an opening in the die part providing access to the pin at its inner end, a cam, means engaged by the cam and movable thereby against the inner end of the pin, means for moving said cam to cause said means to move the pin for a predetermined distance, and means providing for pneumatic pressure on the pin subsequent to said mechanical action to cause said pin to move further.

2. The molding machine of claim 1 including a source of air under pressure to provide pneumatic pressure on the in. P 3. The molding machine of claim 1 including a source of air under pressure providing the impetus for the cam, and the pneumatic pressure on the pin. I

4. The molding machine of claim 1 wherein the cam is tapered and rectilinearly movable.

5. The molding machine of claim 4 wherein the cam has its wider end exposed to the source of air pressure, said wider end having an air passage.

6. The molding machine of claim 5 wherein the air passage is operative only when the cam has been moved a predetermined degree, and means otherwise closing the passage with respect to the pin.

7. The molding machine of claim 1 wherein the means moved by the cam is in the form of a ball.

8. The molding machine of claim 1 wherein the means moved by the cam is a ball, said ball being mounted to allow air to pass it to act on the knockout pin at a predetermined instant during the motion of said cam under influence of the air pressure.

9. An injection molding machine comprising a die, a knockout pin slidable in said die, a head on the pin, a cup-shaped sleeve about said head, a cavity containing the head and the sleeve, a passage through the die part to said cavity and to the base of the cup-shaped sleeve, an elongated bore intersecting the said passage, a tapering cam in the bore and movable therein, said cam having a thin end and a thick end, a loose element in the passage normally located against the thin end of the cam, means forming an air passage in the thick end of the cam, a source of pneumatic pressure directed against the thick end of the cam and acting to move the cam rectilinearly in the bore, moving the element against the sleeve, moving the latter and thereby projecting the pin to a limited degree, the motion of the cam causing the air passage thereto to align with the passage in which the element is located, and to impinge on the' sleeve past said element, for further projection of said pin by pneumatic means.

10. The injection molding machine of claim 9 wherein the cam is conical.

11. The injection molding machine of claim 10 including means to yieldingly hold the cam in position with the ball at its thin portion.

12. The injection molding machine of claim 9 including a multiple arrangement of knockout pins, and elements and passages therefor, the cam also being multiple, the multiple cam and the multiple passages for the elements being constructed and arranged to provide for pneumatic air under pressure to be exerted against all of the pins simultaneously.

13. The injection molding machine of claim 9 wherein the pins are located in the front half of the die.

14. The injection molding machine of claim 13 including a hot runner in the front half of the die.

15. The injection molding machine of claim 14 wherein the pin is located to impinge upon an article closely adjacent to the gate formed by the hot runner along with the article knocked out. w

' References Cited UNITED STATES PATENTS

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