Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTTON
This invention relates generally to phonograph record production,
and more particularly concerns substantial improvements in the construction,
maintenance and replacement of pressing dies.
Recent commercial pressing dies are characterized by rectangular
construction wherein the face-frame and base are of one-piece design. The
four corners of the die act as a heat sink, slowing the performance or usage
time o~ the die, and also creating a non-unifonm heat distribution pattern.
This in turn causes unwanted stresses producing warpage in phonograph records.
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; 10 In addition, the spiral or other groove pattern for passing heating and cool-
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ing fluid in conventional dies makes cleaning and flushing of the grooves
` ~ undesirably diffLcult and time consuming, slowing down the die performance.
~j SU~MARY OF THE INVENTION
:
~ It is a major object of the invention to provide a record pressing
; die construction overcoming the above as well as other difficulties and`
problems encountered in die fabrication, maintenance and usage. Basically,
- ;~ the invention is embodied in a combination that includes: `
,
a) upper and lower die frames, the upp~r die frame attachable to
the upper base, and the lower die frame at~achable to the lower die base, and
b) upper and lower die 4aces, the upper die face attached to the
upper ~rame, and the lower die face attached to the lower frame, the upper
die ~ace directly overlying the lower die face to press a phonograph record
therebetween,
,
c) there being a first set of fluid passing grooves formed in at
; least one of the upper frame and upper face and exposed to the other thereof,
and another set of cooling fluid grooves formed in at least one of the lower
frame and lower face and exposed to the other thexeof.
As will appear, each of the frames and faces desirably has circular
disc shape; insulating plates are employed between the frames and heavier
mounting bases therefor; the frames and faces are connected as by removable
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; fasteners or by brazing; each frame and face pair is removably mounted by a
heavier base.
- Further, the grooves of each frame and face set may be circular and
concentrically formed in the face element; and radial passages are provided to
interconnect the concentric grooves providing multiple (as for example four)
paths for fluid passage between inlet and outlet ducts.
~ These and other objects and advantages of the invention, as well as
the details of illustrative embodiments, will be more fully understood from
the following description and drawings, in which:
DR~WING DE5CRIP~ION
Fig. 1 is an elevation, partly in section, showing one form of the
` invention;
Fig. 2 is a plan view on lines 2-2 of Fig. l;
Fig. 3 is a plan view on lines 3-3 of Fig. l;
` Fig. 4 is an enlarged fragmentary elevation, on lines 4-4 of
Fig. 2;
- Fig. S is an elevation, in section showing another form of the
invention;
Fig. 6 is a plan view on lines 6-6 of Fig. 5; and
; ~ 20 Fig. 7 is a fragmentary plan view on lines 7-7 of Fig. 5.
DETAILED DESCRIPTION
In Fig. 1, the record pressing die assembly IO includes like upper
and lower metallic faces 11 and 12 between which a record is pressed, like
upper and lower metalllc frames 13 and 14, and upper and lower metallic
bases 15 and 16. Each of the frames and faces has circular disc shape, the
thiokness of each frame and face being substantially less than its associated
base. As is clear from Fig. 4, circularly spaced fasteners 17 attach the
frame 14 to base 16l there being through bores 18 in the frame to pass the
fasteners, with fasteners heads 17a received in counterbores 18a. Similar
fasteners attach the upper frame 13 to the upper base 15. Accordingly, each
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; frame and face assembly may be removed from its base, for cleaning, and
insulating plates or discs 19 and 20 may be xetained between the respective
frames and bases to prevent heat transfer between the frames and bases, enabling
speed-up of the heating and cooling cycles, and saving energy. Plates 19 and
20 may consist of glass-epoxy material, or other suitable insulative material,
and they are received against the bottom walls 15a and 16a of recesses 15b and
16b formed by the bases.
Multiple fasteners such as cap head bolts 120 attach the upper
frame 13 to upper face 11, while similar fasteners 21 attach lower frame 14
to lower faae l2. Note that through bores 22 and 23 in the frames pass the
bolts so that bolts holes need not extend to the record pressing surfaces lla
and 12a of the faces 11 and 12. The bolts are equidistantly circularly spaced
in ~h~ree concentric rings, as is clear from Fig. 4. 0-ring seals 24 and 25
seal off between the boIts and bores. A disc shaped gap 26 is formed between
surfaces lla and 12a, the gap having substantially uniform thickness equal
to the thickness of a record to be pressed; however, the gap includes a
thickened peripheral annular pôrtion 26a, as seen in Fig. 1.
The above described construction facilitates separation of each
frame and face pair after its removal from the associated base, as by removal
of the fasteners, thereby exposing heating and aooling fluid passing grooves
for removal of scale build-up or other contaminant or clogging material.
Such grooves are $ormed in at least one of the frame and face elements, and
preferably in the frame side of the face element for open exposure when the
face and frame are separated.
Reference to PigsO 1 and 3 shows the provision of concentric
grooves 101-114 in Eace 12, similar grooves being provided in face 11. Fluid
is communicated to or from innermost groove 114 via duct 115, and fluid is
communicated from or to outermost groove 101 via duct 116. Also, there are
radial passages interconnecting the concentric grooves, and preferably there
are at least four radial escape passages from each circular groove so that
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fluid flows in four streams between the innermost and outermost grooves. Thus,
for example, see the four radial passages 114a---114d interconnecting the two
grooves 114 and 113, and the four exiting fluid streams 114e---114h. Also,
passages 114a and 114b are relatively close, and diametrically opposite close
together passages 114c and 114d. Similar analysis applies to each of the
grooves. Accordingly, flushing time of the assembled die is extremely short,
speeding up the pressing cycle; also the even distribution over the area of
the face disc of the passage pairs associated with successive grooves (i.e.
by symmetrical angular offsetting thereof) assures even distribution of die
, .
- 10 heating and cooling ~ones, reducing stress and warpage in the pressed record.
tNote that the passage pairs are distributed at 45 angles over the face
disc.) Further, since the channels or grooves are circular and not spiral
shaped, machining is simpler. In addition, because of the quadruple channel
design, the channel flow cross section is very large. This allows narrowing
of the channels and reducing the wall thickness between channels without
educing the strength of the die. More channels wi~h less steel between them
provide a much greater heat transfer surface between heating and cooling media
and the die material, speeding up the pressing cycle. As a matter of fact,
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due to the narrowness of the channels, the face thickness can be reduced
; 20 ~without reducing the strength of the die. This again increases the heat
transfer from the hea~ing and cooling media to the plastic, making the die
"faster." Yinally, the face elements may be replaced with minimum expense,
as the frames and bases are re-usable.
Fig. 1 also shows the provision of guide bushings 30 in base 15
receiving telescopically interfitting guide pins 31 projecting from base 16,
to guide the opening and closing together movements of the facea 11 and 12,
along axis 32. Bolster plates 33 and 34 are attached to the bases via thin
plates 35 and 36. Screws 37 retain stamper mounting rings 38 and 39 in
position overlapping the face edges. Center mountin~ structure such as is
indicated at 40 and 41 axially aligns the upper frame and face, and center
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mounting structure as indicated at 42 and 43 axially aligns the lower face and
frame. Tube 40 may receive injection of the record material fed to gap or
zone 26 to be pressed into record shape. Q-rings 44-47 seal off between the
frames and faces at the inner and outer peripheries of the grooves or channels
101 114.
Turning now to Figs. 5-7, the construction is very similar to that
described above, with the exception that the t~o faces 211 an~ 212 are braze
connected to their respective frames 213 and 214, as at peripheral locations
250 and 251, or other locations. Each frame and face paix may be removed and
replaced in its associated base, when desired, and in the manner as discussed
above, i.e. by remov-l of fa6tcner6 2i2 corr66-0ndin7 to fa6t6n6r6 17.
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