U.S. patent number 3,811,645 [Application Number 05/321,204] was granted by the patent office on 1974-05-21 for slide retainer and positioner.
Invention is credited to Karl K. Feist.
United States Patent |
3,811,645 |
Feist |
May 21, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
SLIDE RETAINER AND POSITIONER
Abstract
A slide retainer and positioner for molds having at least one
cam-actuated slide for pulling a core element laterally of the mold
cavity as the mating mold parts are opened, said slide retainer and
positioner being embodied wholly within the mold at all times and
adapted to yieldingly clamp the slide in cam-aligned position only
when the mold is opened without restraining the opening and closing
movement of the slide.
Inventors: |
Feist; Karl K. (North Canton,
OH) |
Family
ID: |
23249634 |
Appl.
No.: |
05/321,204 |
Filed: |
January 5, 1973 |
Current U.S.
Class: |
249/68;
425/DIG.5; 425/DIG.58; 425/438; 425/441 |
Current CPC
Class: |
B29C
45/332 (20130101); Y10S 425/005 (20130101); Y10S
425/058 (20130101) |
Current International
Class: |
B29C
45/33 (20060101); B29c 007/00 () |
Field of
Search: |
;425/438,441,436R
;249/64,66,67,68,122 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Mehr; Milton S.
Attorney, Agent or Firm: Hamilton, Reener & Kenner
Claims
1. In a mold having at least two mating parts abutting at a parting
line and forming a mold cavity and at least one cam-actuated slide
for moving a core part laterally outward and inward of said cavity
during opening and closing of the mold, the improvement comprising
slide retainer and positioner means wholly enclosed within the mold
and having spring-biased jaws for yieldingly gripping an element on
the slide to hold it in aligned position only at the end of the
cam-actuated laterally outward movement thereof and releasing said
element at the beginning of the cam-actuated
2. In a mold as described in claim 1, in which the cam-actuated
movement of the slide is effected by an inclined cam pin on one
mold part slidably engaging an inclined bore on the slide and the
jaws grip the slide element when the pin leaves the bore during
opening movement of the mold parts.
3. In a mold as described in claim 2, in which the spring-biased
jaws comprise a pair of jaws pivotally connected intermediate their
ends, said jaws having opposed jaw surfaces at one end and
compression spring means
4. In a mold as described in claim 3, in which the gripped element
on the slide is a dowel pin and the jaws have cooperating cam
surfaces for
5. In a mold as described in claim 2, in which the gripped element
on the slide is a dowel pin and the jaws have cooperating cam
surfaces for
6. In a mold as described in claim 1, in which the spring-biased
jaws comprise a pair of jaws pivotally connected intermediate their
ends, said jaws having opposed jaw surfaces at one end and
compression spring means
7. In a mold as described in claim 6, in which the gripped element
on the slide is a dowel pin and the jaws have cooperating cam
surfaces for
8. In a mold as described in claim 1, in which the gripped element
on the slide is a dowel pin and the jaws have cooperating cam
surfaces for yieldingly gripping and releasing said dowel pins.
Description
BACKGROUND OF THE INVENTION
In conventional molds for injection molding, for example, in
addition to the mating parts which are designed to abut each other
at a parting line, and to move directly away from each other when
the mold is opened, there are usually one or more core parts which
move laterally into and out of the mold cavity as the mold is
closed and opened. These core parts are connected to slides in the
mold and the slides are actuated by closing and opening movement of
the mating parts through inclined cams or pins on one part slidably
engaging cam surfaces or inclined bores on another part.
Normally the opening movement of the mating mold parts continues
beyond the point where the cam pins become disengaged from the
interfitting inclined bores, and it is necessary that the pins and
bores be maintained in alignment so that during the closing
movement the pins will re-enter the bores and actuate the slides to
move the core parts into position within the mold cavity. When the
mold is opened the slides tend to move into misaligned positions
for several reasons: for example, by gravity if they are in an
overhead position, accidental bumping of the slides by the
operator, or moving the slides due to pulling the product from the
mold cavity in production runs.
To avoid such misalignment conventional molds have usually been
provided with exterior pre-loaded compression spring retainers
attached to the slides and projecting outwardly of the mold to hold
the slides in laterally outward position with the cam pins and
bores aligned after the pins become disengaged during mold opening
movement.
There are a number of disadvantages resulting from the use of these
compression spring retainers. First, the spring retainers have to
be positioned to extend outwardly between the tie rods of the
molding machine, and whenever the mold is inserted or removed from
the machine it is necessary to remove all of the projecting parts
of the spring retainer assemblies in order to get the mold past the
tie rods. Second, pre-loading the retainer springs requires an
additional assembly operation, and when the mold is closed and the
springs are fully compressed, there is always danger of breakage of
the spring assemblies with consequent injury to workmen and loss of
production time. In some cases safety housings for the springs have
been provided but this adds expense and does not prevent loss of
production time if the spring breaks. Third, the pressure of the
spring retainers is applied to the slidably engaging surfaces of
the pins and bores during the entire movement of the pins therein,
with consequent galding of the engaging surfaces. Fourth, in
preparing the mold for shipment an extra large crate is required to
enclose the projecting spring retainers, and an additional clamping
plate is required to hold the mold parts together against the
opening action of the retainer springs.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide an
improved and inexpensive slide retainer and positioner for molds
which will overcome the disadvantages of prior constructions.
Another and more specific object is to provide an improved slide
retainer and positioner which is embodied wholly within the mold so
as not to interfere with the machine tie rods during operation or
during installation or removal of the mold from the machine.
A further object is to provide an improved slide retainer and
positioner which does not require a separate housing for protection
in case of breakage as it is always fully enclosed within the
mold.
Another object is to provide an improved slide retainer and
positioner in which spring pressure is applied to the slidably
engaging surfaces of the cam actuating means only at the end of the
slide-opening movement so as to minimize frictional wear on said
surfaces.
A still further object is to provide an improved slide retainer and
positioner which does not increase the crating size of the mold for
shipment, and which does not require additional clamping means to
hold the mold parts together during shipment.
These and other objects are accomplished by the improvements and
combinations of elements comprising the present invention, a
preferred embodiment of which is shown by way of example in the
accompanying drawings and hereinafter described in detail. Various
modifications and changes in details of construction are
comprehended within the scope of the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of an injection molding machine
having mating mold parts embodying the improved slide retainers and
positioners.
FIG. 2 is an enlarged partial sectional view through a similar mold
of an injection molding machine equipped with the prior
conventional compression spring retainers for holding the slides in
laterally outward aligned positions when the mold is fully
opened.
FIG. 3 is an enlarged vertical sectional view of the mold of FIG. 1
in closed position, taken substantially on line 3--3 of FIG. 5.
FIG. 4 is a similar view showing the mold in fully open
position.
FIG. 5 is a plan sectional view on the mold parting line on line
5--5 of FIG. 3.
FIG. 6 is an enlarged partial plan view of one of the improved
slide retainers.
FIG. 7 is an enlarged partial sectional view on line 7--7 of FIG.
5.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to FIG. 1, a simple injection molding machine is shown
therein somewhat schematically, comprising the material feed hopper
10, the housing 11 for the ram and heater, the nozzle 12, the mold
parts indicated generally at 13a and 13b held together between
stationary pressure plate 14 and movable pressure plate 15. Plate
14 is supported on a base 16 and is connected by tie rods 17 to a
plate 18 mounted on the base and supporting one end of the fluid
cylinder 19 for actuating the movable pressure plate 15. Cylinder
19 has a piston rod 20 connected to the movable plate 15, on which
mold part 13b is mounted, for reciprocating it on the tie rods to
open and close the mold.
Referring now to FIGS. 3 - 5, the mating mold parts 13a and 13b
abut each other at the parting line P in closed position, forming
between them four like mold cavities 22 for molding parts therein.
The feed material from the hopper 10 is heated and then injected by
the ram through nozzle 12 and sprue 23 to the runner 24 and thence
through gate openings 25 into the cavities 22. Core plates 26
extend laterally into each pair of cavities 22 at the parting line.
Extending axially of the mold part 13b are four bores, one from
each cavity 22, in which knock-out rods 27 may be mounted for
aiding in removal of the molded parts when the mold is opened. The
knock-out rods are operated by a knock-out plate 28, in a usual
manner.
The mold parts thus far described may be substantially the same as
those shown in the prior conventional construction of FIG. 2, as
indicated by the same reference numerals, and per se form no part
of the present invention.
In order to move the core plates 26 laterally out of the mold
cavities as the mold is opened, the mold part 13a is provided with
cam elements or horn pins 30, one for each core plate 26, which are
inclined to the parting line and in planes parallel to the
direction of movement of mold part 13b. These horn pins are rigidly
secured in mold part 13a and slidably engage inclined cam surfaces
or bores in slides connected to the core plates 26 to move the core
plates laterally out of the mold cavities as the mold is opened by
moving part 13b away from part 13a on the tie rods 17. Recesses 31
and 32 are provided in the plates of mold part 13b to receive the
horn pins in mold closed position.
The inclined bores 34 for the horn pins are formed in slides 35
mounted for lateral sliding movement in guide rails 36 on opposite
sides of the slide having flanges overlying side flanges on the
slides. The slides and guide rails are mounted in recesses 37 in
mold part 13b at the parting line P, and the recesses 37 extend
laterally outward a sufficient distance to accommodate the improved
slide retainers for holding the slides in aligned positions with
the horn pins after the pins have moved out of the bores 34 when
the mold is fully opened, as shown in FIG. 4.
The outer edges of the core plates 26 are recessed into the inner
ends of the slides 35 and are secured thereto by screws 38, and the
surfaces of the slides merge with the surfaces of the core plates
at the parting line P. The opposite surfaces of the slides slide on
wear plates 39 secured in the bottoms of recesses 37. The outer
ends of the slides have inclined surfaces parallel to the horn pins
which in mold-closed position engage similarly inclined surfaces on
pressure pads 40 secured to the mold part 13a by screws 41 to lock
the slides in place.
The improved slide retainers indicated as a whole at 43 are mounted
in sub recesses 44 within the recesses 37 below the level of the
slides and laterally outward of the slides in the closed position
of the mold. The retainers each comprise a pair of opposed jaw
elements 45a and 45b having interengaging clevises 46a and 46b
intermediate their ends pivoted on a stud 47 screwed into the base
of the sub recess 44. A pre-loaded compression spring 48 is
interposed between the outer ends of the jaw elements, and their
inner ends are provided with opposed cam surfaces 49 connected to
undercut arcuate surfaces 50 for yieldably receiving and clamping a
dowel pin 51 secured in and depending from the outer end of the
slide 35.
In the operation of the improved slide retainers 43, as the mold is
opened by moving mold part 13b away from mold part 13a, the sliding
engagement of the horn pins 30 with the bores 34 moves the slides
and the connected core plates 26 laterally outward of the mold
cavities. At the point where the pins 30 become disengaged from the
bores 34, the dowel pins 51 enter between the cam surfaces 49 of
the jaws forcing them slightly apart against the pressure of spring
48 until the pins 51 are yieldably engaged by the arcuate surfaces
50. Thus the slides are retained in position with the bores 34
aligned with the adjacent ends of the pins 30, so that when the
mold is again closed the pins will enter the bores. It will be
apparent that when the mold closing movement is initiated by fluid
pressure, the pins 51 will force the jaws to open and release the
pins, after which there is no restraining pressure on the sliding
movement of the horn pins 30 in the bores 34. Likewise, the
retainers exert no restraining movement on this sliding movement
during the mold opening movement. Thus, there is no galding of the
slidingly engaging surfaces caused by the slide retainers 43.
The novel slide retainer and positioner is embodied wholly within
the mold so as not to interfere with machine tie rods during
operation of the machine or while changing molds, and there is no
danger from breakage as the springs and retainer assemblies are
always fully enclosed, and no requirement for separate spring
housings. The spring retainer operates only when the horn pins are
disengaged from their cooperating bores so that no restraining
force is exerted on the slidingly engaging surfaces of the pins and
bores during the mold opening and closing movements and no opening
force tending to open the mold when assembled for shipment.
Moreover, since there are no projecting spring retainer assemblies
the shipping size of the mold is minimized.
Referring to the prior art construction of FIG. 2, the slides 135
are connected to pull rods 155 which project outwardly of the mold,
and each slide is urged laterally outward by a pre-loaded
compression spring 156 interposed between the washer 157 at the
outer end of the rod 155 and a stop plate 158 on the side of the
mold part 13b against which the slide abuts when fully retracted. A
safety spring housing is indicated at 160 which projects beyond the
end of rod 155 sufficiently to allow for the retraction
movement.
It will be apparent that all of the disadvantages listed herein
under "Background of the Invention" are present in this prior art
construction and that all of said disadvantages are overcome by the
present improved slide retainer and positioner.
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