JPS59109327A - Blowing shape, blowing molding method and its device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to techniques for blow molding blank articles, and more particularly to an improved blow molding method and apparatus.

Blow molding is a well-known technique used to manufacture hollow plastic items such as bottles. Typically, a tube or "parison" of hot, moldable plastic material is placed between the two halves of the separable mold. □The mold has a mold cavity shaped to match the required external shape of the article to be molded. Each half of the mold is closed around the parison and pressurized air is introduced into the parison to expand it and adapt it to the shape of the mold cavity. The mold is made of plastic material for its final rigidity.

After cooling to shape, the mold is opened and the article is removed. The parison is usually extruded directly through a die into a position between the mold halves, in which case the entire process is called extrusion blow molding.

Articles such as bottles having relatively wide cylindrical bodies and narrow necks can be blow molded relatively easily. However, difficulties are often encountered with blow molded articles having somewhat more unusual shapes. For example, it is difficult to continuously blow mold articles that have relatively large diameter necks and corrugated or other unusually shaped bodies; In order to make all possible
It may have a bellows-like shape. An example of this type of article is the protective shell or "boot" of a motor vehicle's rack and pinion steering system. In order to continuously form the corrugations that define the bellows of this type of article, relatively small diameter parisons must be used.

If the parison has an excessively large diameter, "
□The bellows-like part of the article loses its elasticity. On the other hand, with a parison having a relatively small diameter, it is difficult to form the tone part of the article continuously. □
The following references disclose various conventional nests for mechanically expanding one side of the J1ζ lison to facilitate the forming of articles with unusual shapes.

(US Patent Number) □ L514+183 (Steele et al.) 3+37L3
76 (Fische'r)2+657,431 (
Slaughter)' 3+4I30,290 (
I (inslojv)3+009+196 (Hage
n)' 3+753+384 (Gerlovi
ch) 3+080+614 (Adams) ' 3
,9W,071 (NaLlmann)3+164+6
46 (Fischer) '4+0.32+
278 (Kuenzilg) 3+278+665
(Harriso'n) 4, OI92, 392 (
(Dunbeker) 3+303+249 (Strau
ss) 4,176+153 (Weile'r' et al.) 3+311+950 (Strau5s) (French patent number) 1□ 1+373+990 (Lackner)'
"1',495+618 (Mehnert)1+17
5z974 (Ateliers and Forges
de la Loire)L415,74.7 (A
GK) 1, 44L298 (B.A, S.F.) (British patent number) 781+560 (Glenn Proprietary
y) (German publication number) 1+479,216 (Fischer) L604,6
32 (Moslo) (German Publication No.) L178,580 (Hagen) Another problem encountered when manufacturing articles such as vehicle rudder boots is that the boots should be used in power-assisted steering systems. This is caused by the fact that when wearing a kimono, the inside of the boot must be ventilated. Such systems usually have one boot on each side, which are connected to each other by intake and exhaust pipes, so that
When the system is operated and one boot is compressed,
Air exhausted from that boot moves along the intake and exhaust pipes into the other boot, which then expands. This requires that each boot be provided with an integral mouth or nipple to which the ends of the intake and exhaust pipes can be attached. Typically, the nipple (d) is required to take the form of a small tubular extension, which projects outwardly from the boot near the large diameter neck and has an outer end, and which the outer end is closely adjacent to but spaced apart from the neck;
Furthermore, it extends about an axis parallel to the longitudinal axis of the boot. The passage that completely penetrates the Niraguru clearly communicates with the inside of the boot for intake and exhaust.

This means that the passage must be bent at its inner end. In other words, the nipple has a passageway which has an outer end that is generally parallel to the longitudinal axis of the bellows and an inner end that is bent inward and communicates with the interior of said bellows. .

There are significant practical difficulties in manufacturing boots with integral nipples of this configuration.

In the past, nipples were injection molded separately from the rest of the article;
Subsequently, attempts were made to obtain the same two-soplu by heat welding. However, this requires expensive welding machinery and involves additional manual labor. In fact, this method resulted in a high scrap rate.

It is an object of the present invention to provide an improved blow molding method and apparatus in which nipples and similar forms can all be integrally formed as part of such articles. In one aspect, the method and apparatus of the invention are intended to enable the blow molding of any plastic article having a hollow body, said hollow body having an interior space and an interior space in this space. a primary opening at the end of the body portion communicating and extending about a first axis;
a passage defining a secondary opening near the wide opening; said passageway having an outer portion extending about a second axis spaced apart from said first axis and substantially parallel to said first axis; and an inner portion that is inclined inward toward the axis and communicates with the interior space.

One feature of the method of the present invention is that a divisible mold is prepared.
the mold has mold parts that can be opened and closed, and when the mold parts are closed, setting a mold cavity of a shape that conforms to the required external shape of the article;
The mold cavity extends around a longitudinal axis corresponding to the first axis of the article. When the mold sections are opened, a tubular parison of thermoplastic material in a moldable condition is positioned between the mold sections approximately on the longitudinal axis. The parison entirely encompasses one end to be formed of the primary and secondary apertures of the article, and the parison has a radial dimension that is less than the spacing between the first and second axes of the article. A secondary mandrel and a secondary mandrel are provided, which are shaped to form respectively the wide opening and the outer portion of the passageway in the article to be formed.

These mandrels are each arranged on a longitudinal axis and on a secondary axis corresponding to said second axis of the article. The secondary mandrel has an air duct (air tough) which includes an air outlet located at the outer end of the mandrel and which air exits the outlet in use, or which removes air from the article. It is arranged to form the entire inner end portion of the passage. The ends of the palissono are expanded laterally to a sufficient extent to allow each mandrel to enter its end. Each mantle is then moved into the end of the noyolithon, respectively, along the longitudinal and secondary axes. Each mold section is closed around each mandrel, and the end of the groove opposite the one end is closed. In the next step,
<Air is introduced into the interior of the IJson to expand it and conform to the shape of the mold cavity.

The process includes admitting air into the parison by means of an air duct in a secondary mandrel, in which case the inner end of the passageway within the article by flowing air from said air duct into the interior space of the body portion of the article. part is formed. The parison is allowed to cool to at least a semi-hard state, at which point the parison can be handled and each mold section is opened to allow removal of the molded article.

The present invention also provides an apparatus for fully forming articles of the form described above. The apparatus includes a divisible mold having a plurality of mold parts that can be opened and closed, and which mold parts, when closed, have a shape that conforms to the required external shape of the article. and defining a mold cavity extending □ about a longitudinal axis corresponding to said first axis of the article. When each mold section is opened, a tubular parinon made of a thermoplastic material in a moldable state C can be received between the mold sections. The closing parison □ has a radial dimension smaller than the spacing between the □ - ends of the article and the ends where the primary and secondary openings are to be formed, and the □ first and second axes of the article. has. The apparatus also includes a primary mandrel and a secondary mandrel, each of which is shaped to define a primary opening and an outer portion of the passageway in the article to be formed. on an axis and on a secondary axis corresponding to said second axis of the article, said secondary mandrel having an air duct, said air duct having an air volume disposed at the outer end of said mandrel. each mandrel is arranged such that the air leaving this outlet in use forms the inner end of said passageway. furthermore, the apparatus is movable between an extension position and an extension position in which it cooperates with said mold part to form an outer part of the parison; and includes means configured to laterally widen the ends of the parison located between the mold portions.Air is also introduced into the interior of the parison to expand the parison and expand the mold. Means are also provided for adapting to the shape of the wood cavity, which means for introducing air into the parison through the air duct of the secondary mandrel in order to form the inner end of said passage within the article to be formed. It is also configured as follows.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings, in which preferred embodiments of the invention are illustrated.

Referring first to FIG. 1 in its entirety, a marine boot is briefly described which is a typical example of a plastic article that can be blow molded in a single operation according to the method and apparatus proposed by the present invention. has been done. The boot is indicated generally by the reference numeral 10 and includes a hollow square torso section 12i in the form of a wave or "bellows". This body part has an internal space, and the 1'
Extending around an axis. - A secondary opening 14 is provided at one end of every barrel section and extends about the axis X--X in communication with the interior space of this barrel section.

The opening] 4 is set by a relatively wide neck 1'2a at the relevant end of the body part 12.

The neck 12b, which is considerably smaller than the corresponding one, is the torso portion 12.
, and a smaller opening is set at the other end of the bushing.

An integral nipple 16 is formed on the outside of the trunk portion] 2,
The nipple 16 has an internal passageway (which is located in the body part 1
A secondary opening □ opening 18 is set, which communicates with the internal space of the secondary opening 14 and is close to the secondary opening 14. The internal passageway of the nipple 16 also has an outer portion 16ai, which is a first
The axes X--X are spaced apart and the first axis X--X extends around a parallel second axis Y'--Y. The passageway also has an inner end 16b, which is inclined inwardly toward axis X--X and communicates with the interior space of the body section 12.

1. As previously discussed, there are two major issues associated with manufacturing boot 10 in a single blow molding operation. First, in order to completely continuously form the corrugations on the body of the article, it is necessary to use a relatively small diameter parison, or if such a parison is used, the comparison required for the article in this quiz It is difficult to form the wide neck 12a completely continuously and to determine its dimensions. A second problem is forming the nipple 16 integrally with the remainder of the article.Referring now to FIGS. 2-3, the blow molding equipment used to make the boot 10 can be Encompassing the mold, the mold comprises first and second mold parts, designated 20.degree. 22, respectively. In this particular embodiment, each of the mold parts fully forms 1 and ]/2 of said mold, and these mold halves are arranged between the open and closed positions shown in FIG. It is movable. For clarity of illustration,
The drawings do not show the support for the reservoir of the mold halves, or the means used to move the halves between open and closed positions. These components are all conventional and well known to those skilled in the blow molding art.

The plurality of mold parts are specially shaped recesses 20 a
+22 a f and these recesses each cooperate to define a mold cavity extending about the longitudinal axis when the mold is closed. Said longitudinal axis corresponds to the [th] axis XX of the article and is therefore similarly designated. The mold cavity has a shape adapted to the required external shape of the article to be molded, which in this embodiment is the boot 10.

A portion of the article can be seen in longitudinal section at 10 in FIG. Each mold section also includes a movable mold insert 38, 4.0, which is shown in more detail in FIG. 5 and will be described below in connection with that figure.

Referring again to FIG. 2, the boot 10 is molded from a tubular parinon 42 of thermoplastic material. parison 4
2 is shown in the position it occupies before the actual blow molding operation begins and just before the mold halves 20.22 are closed. At this time, the parison is in a moldable state. ffI] The plastic material Balinone is made from is hot and can be relatively easily deformed by introducing air pressure into its interior. Usually, the parison can be obtained by transversely cutting a tubular extruded material fed continuously or intermittently to said forming apparatus from an extrusion ram, which is conventional in practice in blow molding technology. In Figure 1, the parison is shown emerging from the extruder and resting on its support.

For the reasons discussed above, the parinone 42 is of relatively small diameter, and in fact has a radial dimension that is smaller than the spacing between the axes X--X and Y--Y of the article being molded.

The device therefore includes an "expansion mechanism" for mechanically engaging and expanding the lower end of the parison. This mechanism is indicated generally by the reference numeral 44 and will be described in detail below.

However, before addressing this expansion mechanism, it is convenient to fully open the mandrel assembly. This mandrel assembly appears in the center of the expansion mechanism as shown in Figures 2-3. The mandrel assembly includes a primary mandrel 46 and a secondary mandrel 48.

In FIG. 2, the secondary mandrel appears in front of the primary mandrel, and these two mandrels are best seen in FIG. - The secondary mantle 46 is of relatively large diameter and is designed to set the shape and precise dimensions of the neck 12a of the article. A second mandrel 46 also extends about the axis X--X of the device. The secondary mandrel 48 is of relatively small diameter and is shaped to form the outer portion 16ai of the passageway in the nipple 6 of the article being molded (see FIG. 1).

The secondary mandrel 48 has an air duct 50 therein which includes an air outlet 50a at the outer end of the mandrel, through which the air leaving the outlet is directed inwardly toward the axis X-X. and is configured to form an inner end portion 16b of the passageway in the nipple 16.

In other words, 1. The air coming out of the outlet 50a blows through the plastic material that would otherwise block the inner end of the passage. As a result, the passageway is properly formed and the interior is transparent.

Additionally, air is introduced into the parison through a blower 51ii extending upward from the upper part of the secondary mandrel 46. Blowout pin 51 is of conventional shape and construction and communicates with an air duct (not shown) within secondary mantle 46. The two air ducts in each midrel are supplied with air by any suitable compressed air source of the prior art. The blowing pin 51 can also be seen in Figure 2 and has a series of openings on its outer surface through which air blows into the interior of the parison and causes it to expand. In this figure, the mandrels 46, 48 are shown in the retracted position they occupy just after the parison 42 has been formed, but before the mold sections are closed and blowing has begun. On the other hand, in FIG. 3, the mandrels are shown and shown in their raised position during blow molding. The retracted position of the top end of each mandrel is 1. Indicated by virtual outline. The mechanism for moving each mandrel between their extended and retracted positions will be described below.

With particular reference to FIGS. 2 and 4, the expansion mechanism 44 includes a plurality of parison retaining "fingers j" that extend in an annular manner near the lower end of each mold section and around the blowout pin 51 of the mandrel. arranged in rows, two of these fingers being designated by the numeral 52 in FIG.
By referring to FIG. 4, it can be seen that there are actually eight such fingers, and they are equally spaced around the blowout pin. Each phase is a horizontally movable slider. The slider 54 protrudes upward from the mold cavity 2.
It is parallel to the longitudinal axis of 4. Each slider 24
are movable simultaneously to move each phase between the normal rest position and the retracted position, in which all of the fingers are in close proximity to the blow-off pin 51 (and the parison 42 4), and the retracted position is shown in FIG. 4, in which each phase is disposed such that the lower end portion of the parison is expanded into the shape generally indicated at 42' in FIG. has been moved outside.

It will be noted that each phase 52 moves radially with respect to the axis XX of the mold cavity at any time. However, finger 52
are not all moved with the same radial limit. - The primary and secondary mandrels are each numbered 4 in FIG.
The finger shown at 6.48 and closest to the secondary mandrel 48 (indicated by 521) is moved radially further away from axis X-X and the other fingers, and the fingers on either side of finger 521 (denoted by the symbol 52°) is moved to an intermediate distance so that when the secondary mandrel is raised, the parison is moved far enough that it can enter the end portion of the parison. It can be seen that there is a lateral expansion at the location of the next mandrel. This lateral expansion of the parison is of course not visible in Figure 2, since the cross-sectional view shown in Figure 2 shows that the mold section is This is because it is taken in a plane perpendicular to the matching plane (indicated by P in FIG. 4) and the parison is expanded symmetrically within said plane.

This differential movement between different ones of the fingers 52
It is also shown in the figure that the finger 52' is pulled in (
The expanded position of the parison is shown by a solid line, and the advanced position is shown by a chain-like dotted outline. A diametrically opposed finger 52 is similarly illustrated, with finger 5
2 is seen to move over a much shorter radial distance than the finger '521, this differential movement is achieved by using different shapes of the This is achieved by preparing the entire cam trajectory.

The movement of said finger between the rest position and the retracted (parison expanded) position is shown only in FIG.
Controlled by a pneumatic cylinder and ram device shown in .

Said slider 54 with fingers 52 is mounted in respective radial grooves or sliding passages 60 on the underside of a cover plate 62, which is secured to the housing 58 by means of bolts 64.
(see also Figure 2). As shown in FIG. 4, sliders 54 are approximately in their fully retracted position.

On the underside of the slider 54, the housing 58 has an annular recess 6
6 (FIG. 2), the recess 66 is
Receives an annular member 68 forming an actuation ring for finger 52. The ring 68 is supported by ball bearings 70 for free rotational movement within the recess 66. Each of the sliders 54 is provided with a pin 72 that hangs down from the slider 54 and is attached to a ring 6.
The receptacle is received in an arcuate groove 74 (FIG. 4) on the top surface of 8. A bearing sleeve 76 is mounted within groove 74 around the lower portion of each pin 72.

A similar pin and groove arrangement is provided on each of the sliders 54. The grooves 74 effectively set the cam trajectory and are specially shaped so that rotation of the ring 68 moves all the sliders 54 radially inward or outward according to the direction of rotation of the ring 68. . For example, the fourth
If the ring 68 were to be rotated counterclockwise as seen in the figure, all of the cam trajectories 74 would act on the associated bearing sleeves 76 and pins 72, causing all of the sliders 54
and move the associated finger 52 inward toward the blow-off pin 51. Conversely, if finger 52 is in the rest (extended) position near blowout pin 51 and ring 68 is rotated clockwise, each phase will all move outward at the same time. The range of this movement is determined by the length of the cam trajectory 74 and the angular range over which the ring 68 is rotated.

The cam locus for the slider associated with the finger 521 is indicated by the symbol 74"
The cam trajectory shown by 52
1 moves further outward than the other fingers in the radial direction.

Similarly, the cam trajectory associated with finger 52'' is indicated by 74'' and is slightly more curved than trajectory 74', but much less curved than the other cam trajectories. This difference in curvature between the various trajectories causes corresponding differences in the associated radial movement of the fingers.

Rotation of the ring 680 is effected by the cylinder and ram arrangement 56 described above. The ram of device 56 is indicated at 78 and has a fitting 80 at its outer end. A link pin 82 extends vertically upwardly from the joint 80 through an arcuate groove 84 in the bottom wall of the housing 58 and is secured at its upper end to the ring 68. Therefore, Ram 78
When the ring 68 is extended and retracted, the ring 68 moves through an arbitrary range of angles. This range of angular movement is determined by the stroke of ram 78, which stroke is selected to match the required movement of finger 52.

In an alternative embodiment, the cylinder and ram device 5
6 can be replaced by a hydraulic motor, which is installed perpendicular to its 1 drive shaft,
The spur gear is attached to the upper end of the drive shaft.

This spur gear meshes with a corresponding ring gear mounted on the underside of the ring 68, so that the ring 68 can be rotated by operating the hydraulic motor. The hydraulic motor should obviously be properly geared and should be reversible.

FIG. 2 shows how the slider 54 supporting the fingers 52 also serves to position the parison 42 before the start of the blow molding operation. The parison should therefore be arranged such that its lower end extends beyond the lower ends of the mold parts 20,22. In the embodiment described and illustrated, this end of the parison is connected to finger 52 of expansion mechanism 44.
and expanded. However, in alternative embodiments of the invention, the fingers may engage the parison within the range of movement of the mold parts, in which case the expansion mechanism is configured to be retracted downwardly as each mold part is closed. Ru. In any case, the parison should preferably not be expanded beyond its required final size and shape. This is because otherwise the mold parts tend to become obstructed or obstructed when closing.

As previously discussed, enlarging and stretching the lower end of the parison by finger 52 causes mandrel 46.
can move upward into the parison. This movement is accomplished by a pneumatic cylinder and ram system (FIG. 2) which is mounted in a vertical position below the mandrel assembly and whose ram is connected to the assembly.

The same ram is therefore fitted with a transverse plate 88 on which the primary mandrel 46 is mounted. A bracket 90 is secured around the primary mandrel 46 at a distance above the plate 88 and the mandrel 48 is secured to the bolt 92.
The bolt 9 □ 2 extends upward through a portion of the bracket 90 and is screwed into the lower end of the mandrel 48 . Bolt 92 is configured as a sump fitting for the air supply to mandrel 48 . As mentioned above, the blowing pin 51 extends upward from the top of the mandrel 46,
Only a portion of the same pin is visible in FIG. Blowout Pino 51
The upper end (see Figure 2) is shaped to cooperate with each mold section and close the upper end of the parison when the mandrels are in their raised position.

At this time, only the upper end portions of the two mandrels actually enter the parinon. These parts cooperate with the mold inserts 38, 4.0 mentioned above, and both mandrels and these mold inserts are closely dimensioned so that the molded article, rather than blow molding, □ Also, compression between these inserts and the mandrel forms the neck region and nipple 16 of the molded article. In other words, the neck region of the article is actually compression molded, while the body portion is blow molded (as are the inner ends of the passages 1 of the tuples 16). : An annular groove 9'4 is provided around the upper end of the mandrel 46 in order to form a corresponding protruding rib on the inside of the neck of the molded article;
I'm being kicked. Similar grooves 96 are formed around the upper end of mandrel 48 to form similar ribs on the inside of nipple 16.
is provided. These ribs assist in properly securing the boot to the helm/stem component when the article is installed.

said mold insert 38.40 releases the neck of the molded article;
It is constructed so that it can be pulled away from each mandrel in order to allow the front to flex sufficiently to allow the manton ille to be withdrawn without damaging the forming ribs formed by the grooves 94,96.

The mold part 20 ) 22 is provided with four parts each having parallel sides, and these recesses receive all of the inserts and release the pressure on the molded article from their normal molding position. The objects can be slid toward each other and away from each other until the retracted position is reached. Insert 38 is seen in FIG. 3 and includes a projecting flange 38d.
It can be seen that a is formed. This flange 38d is received within a complementary undercut of the recess in the mold half 20, allowing the insert 38 to fully slide. The insert 4o is similarly supported within the mold half 22. Each insert has an edge 381 at their lower end.
r (Fig. 3), each having inwardly projecting peripheral edges which cooperate with each mandrel to cut off the excess lower end portion of the parison when the mold halves are closed. .

The movement of the two inserts between the advanced and retracted positions is carried out by means of a pneumatic shilling and ram device], ], 2
, 114, respectively, and these devices 112. ], ], 4 are attached horizontally to the rear side of the mold section, some of which are visible in FIG. With continued reference to the figure, the inserts 38, 40 have respective sliding passages which are undercut on their outer sides] ], ]6
, 1.1.8 i, and these sliding passages ], i 6 , 1-1.8 are seen to be slidably engaged with the associated actuator sliders. These actuator sliders are interlocked with each of the /linder and ram devices 112 and J]4. These sliders are not shown in detail, but the two inserts 38
．． 40 or shown in plan view in FIG.
Suffice it to note that 1.6, 1.18 is inclined with respect to the connecting line between the gl1 parts 20.22 in the two molds. Therefore, as each slider moves longitudinally under the control of the cylinder and ram arrangement associated with each slider], ], 2, 11.4, the insert 38, 4-0 correspondingly moves with respect to the mold cavity 24. Move radially.

Referring to FIG. 5 above, each of the inserts 38 and 40 has a main arched recess for receiving the entire primary mandrel and four similarly shaped smaller sections for receiving the secondary mandrel. I understand that you have it. Those recesses in the inserter l.38 are designated by the reference numeral 38. a and 3
8, while the corresponding four parts in the insert/1° are designated 40a and 401].

The insert 40 is provided with a slider 120, and the slider 120 is biased toward the recess 4Ob by a compression spring 122. The twisted slider 1.20 has an outer edge 120ai curved to engage the mandrel 48 inside the recess 4-Ob and is held by a pin 124, which extends through an elongated hole tX in the slider 124. so that when each insert is separated from one another, the slider 120 can move within the limits allowed by the optical slots. Ushida, slider], 2
0 has a substantially T-shaped cross section, and the receiver is placed within the T-shaped sliding passage 125. The cross-sectional shape of the sliding passage 25 can be seen in FIG. A slider, also spring-biased and generally designated 120', is provided within the insert 38. The purpose of these spring-loaded sliders is to provide a slight holding force to the two-piece assembly on the molded article as the mandrel 48 is withdrawn, thereby minimizing the risk of distorting the two-piece member. There is a particular thing.

The general apparatus provided by the present invention is supported by four struts, two of which are indicated at 128 in FIG. 2 and extend upwardly from Hayspray 1-130. Each strut is provided with a threaded adjustment body 132 at their lower end. Also, the four pillars at their upper ends are four poles) 134. (FIG. 4) is attached to the actuator housing 58. The device 86 for actuating the mandrel assembly is carried by a bracket 136 depending from the how/puffer 58.

A typical molding process will first be fully described with reference to Figures 2-3.

With the mold halves 20, 22 in their open position and the mandrel assembly retracted, the parison 4
2 is placed so as to exceed the exposed portion of the blow-off pin 51 of the mandrel. Typically, the parison is extruded to this position and supported at its upper end by an extrusion device. At this time, said cylinder and ram devices 112, 114 associated with the mold inserts 38, 40 are actuated, so that each insert reaches its advanced (forming) position and each phase 52 moves into its position near the blowout pin 51. Reach rest position. After the parison reaches the position shown in FIG. 2, each phase 52 is moved outwardly by actuating the cylinder and ram device 56 to expand and stretch the lower end of the parison.

Each mandrel 46;48 is then raised to the position shown inside the parison in FIG. The mold halves are then closed onto the mandrel to capture the parison.

Air pressure is then introduced into the parison via the mandrel blow-off pins 1 and the mandrel 48. This causes the parison to fully expand into contact with the mold halves and conform the parison to the shape of the mold cavity. At the same time, nipple 16
An inner end 16b of the passage is formed.

The pariso/is then cooled to a relatively rigid state. Air pressure is then released and each ram of said cylinder and ram devices 112, 114 is inserted into the mold insert 38,40.
' and is retracted to relieve the external pressure of the front stop of the molded article.

Each mandrel then retracts and each mold half opens, leaving the molded article supported by fingers 52 and sliders 54. Finally, the shaped article is removed in a manner known per se by a "wiper" mechanism operated manually or by an air cylinder. The inserts 38,40 then return to their forward position ready for the next operation.

It will, of course, be understood that the above description relates only to preferred embodiments of the invention, and that many modifications are possible within the broad scope of the invention.

It should also be noted that the methods and apparatus disclosed herein may be used to form articles other than those specifically mentioned above. According to another feature, the method and apparatus of the invention can be used to manufacture articles in which the secondary openings are not arranged around an axis parallel to the axis of the primary opening of the article. In other words with reference to FIG. 1 of the drawings, the axis Y--Y does not necessarily have to be parallel to the axis X-=X. for example,
The nipple 16 is at an angle (e.g. 459
can extend around an axis arranged to make an angle). In that case, the secondary mandrel should be provided with a separate actuation device. □In other words, two mandrels cannot be operated in the manner shown by the same cylinder and ram arrangement. Obviously, special structures must be provided to widen the parison when the article is to be of non-circular shape, but the invention is not limited to articles of circular cross-section.

Although movable inserts 38,40 are preferred in this embodiment, they are not essential; for example, if the molded article has a flat neck, such inserts may not be necessary.

It is also not necessary to radially expand the inner end of the parison in all cases. Depending on the article, it may be sufficient to expand the parison only to accommodate the secondary mandrel. It is then possible for each phase located around the rest of the article to remain stationary and simply hold all the halinons in place, or in some cases even omit those fingers.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a boot made according to the invention for a power-assisted rack and pinion steering system; FIG. 2 is a perspective view of a boot made according to the invention with each mold section in the open position FIG. 3 is a partially cut-away side elevational view of the forming apparatus; FIG. 3 is a somewhat schematic partial vertical sectional view at the center of FIG. 4 is a plan view of the expansion mechanism used to expand the parison according to the method of the invention; FIG. 5 is a cross-sectional view taken in a vertical plane; FIG. FIG. 3 is an inverted plan view showing the surrounding structure with the two mold inserts completely omitted; 10...Buno 12...Body part 12a...Large diameter Neck 12b...Small diameter
Neck 14...-wide opening 16, two-way opening 16a...outer portion 16b...inner end portion 18...
Secondary openings 20, 22... mold portions 20a, 222.
・Concavity 38.40 ・Mold insert 42
...Paris non 44...Expansion mechanism 46...-Next mandrel 48...Z-th order?
L/Le 50-Air duct 50a Air outlet 51・・Blowout pin 52・・Finger 54・・・2 Sliding 56・/Rinder and ram device 58・・Housing 60・・・Sliding passage 62... Cover one plate 64... Vol Toro 6...
・Concave part 68...Ringa 0
・・・Ball bearing 72・−・・Pi
74...Groove (cam locus) 76 Bearing sleeve 78...Ram 80...Joint
Hand 82...Pin 84...Groove 86
・Air pressure pulling and ram device 88...Transverse grout L/-t 90...Bracket 92...Bolt
G 94.96・Groove 112.114・・・・
Pneumatic cylinder and ram device 116.1.18/Sliding passage 120-Slider 122...Compression spring 1
24... Pin 125 ・Sliding passage 13
0-Base plate 132...Screw-like adjustment body 134
・Bolt 136・Bracket X-X・No. 1
Axis Y-Y...Second axis

Claims (1)

[Scope of Claims] (1) A method of blow molding a plastic article, the plastic article having a hollow body portion, the body portion communicating with the interior space and having a first
defining a primary opening at an end of said body portion extending about an axis and a passageway defining a secondary opening proximate said secondary opening, said passageway being spaced from said first axis and defining said opening at said first axis; divisible in a manner including an outer portion extending about a second axis substantially parallel to one axis and an inner portion inclined inwardly toward the first axis and communicating with the interior space; the process of providing a mold, the mold having mold parts that can be opened and closed, and when these mold parts are closed, defining a mold cavity, which mold cavity forms the desired external shape of the article; forming a substantially tubular parison of thermoplastic material in a moldable condition with the mold portion fully open; positioning between the mold portions on the longitudinal axis, the parinon encompassing one end to be entirely formed of the primary and secondary openings of the article, and the first and second axes of the article; and providing primary and secondary mandrels, the mandrels having a radial dimension smaller than the spacing between the openings and the passages, respectively, in the article to be formed. shaped to form a part,
and each of these mandrels is arranged on said longitudinal axis and on a secondary axis corresponding to a second axis of said article, and further said secondary mandrel has an air duct), said air duct including the entire air outlet. the air outlet being disposed at an outer end of said secondary mandrel and arranged such that, in use, air leaving said air outlet forms an inner end portion of a passageway in said article; laterally expanding one end of the parison to a sufficient extent to allow the mandrels to enter one end of the parison; and extending each of the mandrels along the longitudinal axis and the secondary axis moving into one end of the parison; and closing the mold portion around the mandrel;
closing an end of the parison opposite the one end; and introducing air into the interior of the parison to expand the parison and adapt it to the shape of the mold cavity, the steps of: introducing air into the parison by a duct, the air being forced into the article by flowing the air from the air duct into an interior space of a body portion of the article; A method of blow molding comprising: forming the parison; cooling the parison to an at least semi-hard state where it can be handled; and opening the mold section to allow removal of the molded article. (2,1+ The step of laterally expanding one end of the parison includes expanding the one end in the radial direction, and expanding the one end at a position of the secondary shaft to which the secondary mandrel can move) (3) The step of laterally expanding one end of the parison includes the step of laterally distorting the parison. by providing mating elements disposed in a generally annular configuration about the longitudinal axis of the mold cavity, and protruding into one end of the gas parison generally parallel to the longitudinal axis; All of these elements are moved simultaneously along a straight path extending perpendicular to said axis and radially outward with respect to said axis, while each element remains substantially parallel to said axis. and the one end of the parison is held unobstructed, and at least one of the elements at the secondary axis has a longer radially outward extent than the remainder of the elements. 3. A method according to claim 2, characterized in that the parison is moved thereby causing a lateral distortion of the shape of the parison. (4) within the region of the opening and passageway. For setting the outer shape of the article, the mold portion includes respective inserts defining surface portions of the mold cavity, and each of the precursors includes a rib projecting inwardly within each opening of the molded article. at least one external annular groove to form a
withdrawing the mandrel from the parison; and after the parison has been expanded, but before withdrawing the mandrel, releasing pressure between the insert and the mandrel to allow the molded article to bend; 2. The method of claim 1, further comprising the steps of: enabling the forming ribs to be removed from the grooves of the mandrel as the mandrel is withdrawn. 5. The method of claim 4, further comprising the step of mechanically restraining an end of the molded article in which the passage is formed when the secondary mandrel is withdrawn. (6) An apparatus for blow molding plastic articles of the type having a hollow body, the hollow body having an interior space communicating with the interior space and extending around the circumference of a first shaft. defining a primary aperture at the end of the body portion that is present and a passageway defining a secondary aperture proximate the secondary aperture;
The passageway has an outer portion extending about a second axis spaced apart from and generally parallel to the first axis, and an outer portion inclined inwardly toward the first axis and communicating with the interior space. an apparatus comprising a divisible mold, the mold having a plurality of mold parts which can be opened and closed, and which mold parts, when closed, contain the required amount of the article; a mold cavity having a shape adapted to the external shape and extending about a longitudinal axis corresponding to the first axis of the article; can receive a tubular nochrysone of material, said nochrisson having first and second openings of said article with the ends thereof meeting to form the primary and secondary openings of said article, and - a primary mandrel and a secondary mandrel, each mandrel shaped to define the primary opening and the outer portion of the passageway in the article to be formed, each mandrel having a respective longitudinal axis '2', and second item
said secondary mandrel has an air duct '1 which includes an air outlet located at the outer end of said mandrel and which, in use, is arranged on a secondary axis corresponding to said mandrel; said mandrels are arranged such that air leaving said mold part forms an inner end of said passageway, said mandrels being arranged so as to form an inner end of said passageway, said mandrels being arranged to form a retracted position remote from said mold part and said opening and an outer part of said passageway. a parison movable between said mold parts and a cooperating extension position, and further positioned between said mold parts with sufficient range to enable said each →endrel to enter one end of said parison; means configured to widen one end laterally; and means for closing an end of the parison opposite the one end; The air duct H of the secondary mandrel is provided with means for expanding and adapting the shape of the mold cavity to form the entire inner end of the passage within the article to be molded.
- A blow molding apparatus, characterized in that the blow molding apparatus is configured to allow all of the air to flow into the parison through the parison. (7) The means configured to laterally expand the ends of the parison include a plurality of parison engagement elements, the elements being generally annular about the longitudinal axis of the mold cavity. arranged in a shape and substantially parallel to said longitudinal axis, said means comprising support means for said element, said support means being arranged in a straight line arranged radially with respect to said longitudinal axis; multiple motions of the elements between first and second positions along a path and in a plane perpendicular to the longitudinal axis, while maintaining the arrangement of the elements substantially parallel to the longitudinal axis; wherein in the first position the element is disposed close to the longitudinal axis to enable installation of the parison on itself and in the second position radially outwardly from the first position. being displaced to expand one end of said paris, and said means comprising means for simultaneously moving said element between its first and second positions, said means being adapted to move said element at said secondary axis position; at least one of the elements is moved radially outwardly over a longer range than the other elements, so that the balin/ is deflected outwardly over a wider range at the location of the secondary axis; 7. The device according to claim 6, characterized in that: (8) the support means includes a plurality of sliding members corresponding to the plurality of parison engagement elements, each sliding member supporting one of the elements at its inner end; Projecting generally perpendicularly and upwardly from the sliding member, the support means includes an annular housing having a central opening through which the
the mandrel is movable between their retracted and extended positions, and the housing is configured such that the sliding member is movable between the first and second positions. and supporting a front sliding member so as to slide horizontally in the radial direction of the housing between the second positions;
said means for moving said element between said positions comprises an actuator ring, said ring being pivotable about an axis Ω of said central opening defined by said housing;
cam means supported by said housing and for said means to rotate said ring within a predetermined angular range; and cam means for coupling said actuating ring and said sliding member; Cam means are arranged to longitudinally slide the sliding member in response to rotation of the ring, and the cam means imparts differential movement to the sliding member to cause distortion of the parison. 8. Apparatus according to claim 7, characterized in that it is configured to perform. (9) further comprising a plurality of mold inserts', each of these inserts being carried by one of the mold parts and for molding the exterior of the article in the area of the secondary and secondary openings; setting a surface portion of the mold cavity;
Each of the inserts is movable between a normal forward molding position for cooperating with the mandrel and a retracted position for relieving pressure between the mold section and the mandrel; 7. Apparatus according to claim 6, characterized in that it comprises means for moving the parts between their forming and retracting positions. QO) 1. of the above-mentioned insert. The sliding member is biased by a spring and envelops the material, and this sliding member is elastically pressed against the outer surface of the molded article in the outer end region of the passage 9 of the molded article. 10. The apparatus of claim 9, wherein the apparatus is constructed and configured to provide retention to the area while the secondary mandrel is withdrawn from the outer portion of the passageway. ,. (11) A blow-molded plastic article having a corrugated body portion, the body portion having an interior space;
defining a primary opening at the end of the body portion communicating with the interior space and extending around the first axis, and a passageway defining a secondary opening near the primary opening; The passage includes: an outer portion that extends at an angle with a second axis that is spaced apart from the first axis and substantially parallel to the first axis, and an inner portion that is inclined inwardly toward the first axis. an inner portion communicating with the space, the article being formed by blow molding in a single operation. (12) A method for full blow molding a plastic article, wherein the plastic article has a hollow body portion, the body portion communicating with the interior space and extending about an axis. A method for defining a primary opening at an end of the body portion and a secondary opening disposed proximate the secondary opening and communicating with the interior space, the method comprising: providing a divisible mold; The mold has mold parts that can be opened and closed, and when these mold parts are closed, they define a mold cavity and 1. The mold cavity has a shape that matches the required external shape of the article, and
extending about a longitudinal axis corresponding to the axis of the article; opening the mold section and forming a relatively narrow tube of thermoplastic material in a moldable condition; positioning a parinon between the mold parts approximately on the longitudinal axis, the second lison encompassing the primary two of the article and one end to form the secondary opening; providing a secondary mandrel and a secondary mandrel shaped to form the secondary and secondary openings, respectively, the secondary mandrel having an air duct, the air duct extending from an outer end of the mandrel; laterally extending one end of the previous parison with a process including an air outlet located in the parison and of sufficient extent to allow each mandrel to enter one end of the parison. expanding each mandrel into one end of the parison; and closing the mold portion around the mandrel;
a step of closing an end of the parinon opposite to the one end; and a step of completely introducing air into the inside of the parinon to expand the parinon and adapting it to the shape of the mold cavity, the steps of a total inflow of air into the parison by a tact, wherein the air flows from the tact into an interior space within a body portion of the article to provide communication between the secondary opening and the interior space; A method of blow molding comprising: ensuring that the Harrison is fully cooled to at least a semi-hard state size to permit handling; and opening the mold portion to permit removal of the molded article. (13) An apparatus for full blow molding a plastic article of the type having a hollow body, the hollow body having an interior space communicating with the interior space and extending about two axes. a primary opening in the end of said body portion, which is located therein, and a secondary opening located in the vicinity of said secondary opening and communicating with said interior space; The mold comprises a divisible mold, the mold having a plurality of mold parts which can be opened and closed, and which mold parts, when closed, have a shape that conforms to the required external shape of the article; a mold cavity extending about a longitudinal axis corresponding to the axis of the article, wherein the mold portion and the open position receive a relatively narrow tubular parison of thermoplastic material in a formable condition; The parison may include ends to form the primary and secondary openings of the article, and may include a primary mandrel and a secondary mandrel, each mandrel being adapted to form the article to be formed. The secondary mandrels are shaped to form secondary and secondary openings, each of the secondary mandrels having an air outlet disposed at an outer end of the mandrel; each mandrel is movable between a retracted position away from the mold portion and an extended position cooperating with the mold portion to form the secondary and secondary openings; means configured to laterally widen one end of the parison located between said mold portions to a sufficient extent to permit entry into the parison; and an end of the parison opposite said one end. and means for introducing air into the interior of the parison to expand it and to adapt it to the shape of the mold cavity, the means comprising: The blow molding is configured to allow air to flow into the parison through the duct in the secondary mandrel to ensure full communication between the secondary opening and the interior space. Device.