Note: Descriptions are shown in the official language in which they were submitted.
2011802
This invention relates to a method and apparatus for
blow molding a hollow body, and in particular to a method and
apparatus for blow molding an automotive boot.
Automotive boots for covering grease coated joints
generally include a bellows-shaped body and cylindrical
sleeves or collars at each end of the body for mounting the
boot on automotive components. A problem inherent to the
production of such boots is the formation of a generally
cylindrical sprue or flash which must be removed from the boot
in labour intensive finishing operations.
The object of the present invention is to provide a
relatively simple method and apparatus for producing an
automotive boot without a flash.
According to one aspect, the invention relates to a
method of molding an automotive boot of the type including a
bellows-shaped body and a pair of end collars for mounting the
boot on automotive componentsl said method comprising the
steps of extruding a parison; moving said parison into an open
mold; introducing a blow pin assembly into the open top end of
the parison to hold the top end of the parison open; closing
the mold around the parison and sleeve; stretching the bottom
end o thè parison open; inserting a mandrel into the open
bottom end of the parison; introducing air under pressure into
the parison to preblow the latter; compressing the bottom end
of the parison against said mandrel to form a first said
collar; moving a blow pin into the open top end of the parison
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to press the top end of the parison against the mold to size
the second said collar and to separate the top end of the
parison therefrom; and introducing air under pressure through
said blow pin into the parison to blow the latter against the
mold to form the body of the boot between said first and
second collars.
The invention will be described in greater detail
with reference to the accompanying drawings, which illustrate
a preferred embodiment of the invention, and wherein:
Figure 1 is a schematic, longitudinal sectional view
of the top portion of an apparatus for effecting a method of
the present invention; and
Figures 2 to 9 are schematic, longitudinal sectional
views of the apparatus of Fig. 1 in a variety of molding
conditions.
With reference to Fig. 1, an apparatus for carrying
out the method of the present invention includes a mold
generally indicated at 1 defined by a pair of mold halves 2
and 3. The mold halves contain recesses 4 and 5, which
together define a`mold cavity in the shape of a boot 6 ~Figs.
6 to 9) when the mold is closed ~Fig. 1).
The cylindriaal top end 8 of the mold cavity is
closed by a blow pin assembly generally indicted at 10. The
assembly 10 includes an arm 11 supporting the assembly and
containing a passage 12 for introducing air under pressure
into the assembly. A pneumatic cylinder 13 is carried by the
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arm 11. A piston 15 is caused to reciprocate in the cylinder
13 by air ~ntering and leaving the cylinder via openings 16
and 17 above and below the piston. A blow pin 18, which is
connected to the piston 15 extends downwardly through an
opening 19 in the arm 11 and through a sleeve 20. The lower
end 21 of the cylinder 13 and the closed upper end 22 of the
sleeve 20 and the opening 19 in the arm 11 define an air
receiving chamber. Air entering the chamber is discharged
via openings 24 in the upper end 22 of the sleeve 20 into a
chamber 25 between the rod 18 and the sleeve 20. The large
body 27 of the pin 18 is slidable in the sleeve 20, with an O-
ring 28 therebetween for sealing purposes.
During use, the pin 18 and the sleeve 20 extend
downwardly through a parison carrier arm 29 and mold inserts
30 into the open top end 8 of the mold cavity. Air passages
32 and 33 in the body 27 and head 35, respectively of the pin
18 carry air to the mold cavity during a blow molding
operation.
The inserts 30 are blocks mounted on the top of the
mold halves 2 and 3. Semicircular recesses in the inserts 30
define a circular opening when the mold is closed for
receiving the pin 18 and the sleeve 20. Striker plates 36 are
provided in the top of each insert 30 for engaging and
centering the bottom end of the sleeve 20, i.e. the plates 36
ensure that the sleeve 20 and the blow pin 18 are accurately
centered in the mold. Striker plates 38 are mounted in
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opposed recesses in the top of the mold halves 2 and 3, and in
the bottom of the inserts 30. The striker plates 38 have a
sharp bottom inner edge for cooperating with a cylindrical
cutting sleeve 39 on the pin 18 for cutting a parison 40
(Figs. 2 to 5).
As shown in Figs. 2 to 9, the elements defined above
are used in combination with a pair of sliding inserts 42 on
the bottom of the mold halves 2 and 3, stretcher fingers 43
and a sizing mandrel 44 to form a boot 6. The inserts 42 and
the stretcher fingers 43 are designed and operate in the
manner described in detail in U.S. Patent No. 4,396,574,
issued to S.A. Kovacs on August 2r 1983. In general terms,
the fingers 43 are slidably mounted in a block for radially
moved toward and away from the longitudinal axis of the mold
cavity. The sizing mandrel 44 is mounted on the top end of a
piston/cylinder arrangement (not shown) for vertical movement
along the longitudinal axis of the mold cavity. The inserts
¦ 42 include an inclined upperr inner surface 45 designed to
form the bottom end 46 (Figs. 8 and 9) of the bellows portion
of the boot 6r and a cylindrical lowerr inner surface 48 which
cooperates with the mandrel 44 in forming and sizing the
cylindrical collar portion 49 of the boot 6.
The method of the present invention will be
described with specifia reference to Figs. 2 to 9. With the
mold sides 2 and 3 separatedr i.e. with the mold 1 openr the
blow pin assembly 10 is off to one sider the sizing mandrel
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and stretcher fingers are below the mold, and the sliding
inserts are in their outermost position. A parison 40 carried
by the arm 29 is placed between the mold halves 2 and 3, and
the fingers 43 and the mandrel 44 are moved upwardly to
position the fingers in the bottom end of the parison 40. The
blow pin assembly 10 is moved into position above the center
of the mold 1.
The mold 1 is closed by moving the mold halves 2 and
3 together. A fraction of a second before the mold closes the
sleeve 20 of the assembly 10 is introduced into the flared
open top end 50 (Fig. 3) of the parison 40. The fingers 43
are moved radially apart to stretch the bottom end 52 (Fig. 3)
of the parison 40 so that the sizing mandrel A4 can be
introduced into such bottom end 52 (Fig. 4).
Air under pressure is introduced into the parison 40
to preblow the latter, and the sliding inserts 42 are moved
together against the bottom end 52 of the parison 40 to size
the bottom end (Fig. 5). Blowing of the parson 40 is effected
to form the boot 6. The head 35 of the blow pin 18 defining
an upper sizing mandrel is moved downwardly into the top of
the boot 6 to compress, i.e. size the neck 53 of the boot 6
(Fig. 6) in a flashless manner. During such sizing, the
sleeve 39 (Fig. 1) cuts the top end of the boot, removing the
tops of the parison therefrom.
With the formation of the boot 6 completed, the
lower inserts 42 spread apart, i.e. opened and the mandrel 44
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is removed from the boot 6 (Fig. 7). The fingers 43 move
together or close and the mold 1 opens (Fig. 8). The blow pin
assembly 10 is stripped from the boot 6 by moving the piston
15 upwardly in the cylinder 13 (Fig. 9), and the assembly is
S moved to one side so that a fresh parison 40 can be introduced
to start the process again.
In an alternate method, following movement of the
parison 40 between the mold halves 2 and 3 (Fig. 2), the blow
pin assembly 10 is moved downwardly into the top end of the
parison 40 (Fig. 3) and the mold 1 is closed by moving the
mold halves 2 and 3 together.
The fingers 43 are moved apart or opened to stretch
the bottom end of the parison 40, and the sizing mandrel 44 is
moved upwardly into the open bottom end of the parison 40.
The inserts 42 at the bottom of the mold are then closed to
size the bottom end 52 of the parison 40, and the parison 40
is blown, i.e. air under pressure is introduced into the
parison 40 via the blow pin assembly 10. The blow pin
assembly 10 is moved downwardly into the parison 40 to size
the top ehd 50 thereof, i.e., the cutting insert 39 and the
striker plate 38 cooperate to cut the parison 40 while the
head 35 sizes the neck of the boot 6. The sliding inserts 42
are opened, and the head 35 defining the lower sizing mandrel
44 is moved downwardly. The mold 1 is opened, the fingers 43
are closed, and the blow pin asssmbly 10 is stripped from the
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boot 6, which is then removed from the machine to complete
the operation.
In Figs. 8 and 9, the top end of the boot neck 53 is
shown as having a concavo-convex cross section. This shape,
which is not shown in Figs. 3 to 7, is caused by the concave
annular groove (Fig. 1) in the arm 29. The remaining views 2
to 7 are quite schematic and accurately illustrate neither the
structure at the top of the mold shown in Fig. 1 nor the shape
of the top end of the parison during molding.
It will be appreciated that the method and apparatus
described above can be used to produce other boots and similar
articles of manufacture.
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