RU2186683C1 - Extrusion-inflation moulding machine - Google Patents

Abstract

FIELD: equipment for manufacture of hollow articles by inflation in moulds with movable parts of blanks preliminarily moulded by extrusion, of polymeric materials in a plastic state, applicable in production of small-piece containers in the form of bottles, cans, fuel cans, etc. SUBSTANCE: machine has a bed frame carrying an electric-heated extruder with a head moulding the tubular endless blank, positioned under which is the piece blank separation mechanism, vertically the movable nozzle for feeding of in-process air to the mould, consisting of linked half-moulds installed on the mounting plates coupled to the positioning air cylinders, grippers being distant from the half-moulds by a positioning spacing, and a flash removing mechanism. The tapered vertically movable nozzle has a band calibrating the article neck and adjustable in height, installed in alignment with the article grippers, made in the form of symmetrical semi-rings rigidly coupled to the mounting plates of the respective half-moulds. The mounting plate drive cylinders are installed on independent synchronized positioning air cylinders, and their rods are longitudinally fixed on the bed frame. Trapezoidal protrusions conjugated in pairs in the plane of linking for the closing tapers, hinge-mounted on the rods of the air cylinders rigidly coupled to the mounting plates, are made on each half-mould on both sides of the linking plane. The piece blank separation mechanism has a double-arm lever of the first order freely coupled by its smaller arm to the rod of the drive cylinder, and a double-edged rhomb-shaped knife is fastened on the larger arm. The flash removing mechanism has a horizontal knife of the triangle-shaped neck coupled to the drive, and a knife of steel blade made in the form of an arch, congruent surface of the article bottom, fastened on a lever swinging along the linking plane in the groove of the box-type unloading slide. EFFECT: enhanced functional reliability of the moulding machine, simplified construction and improved quality of manufactured articles, simplified kinematics, enhanced convenience of adjustment and servicing, easy readjustment to various standard sizes of polymeric containers. 2 cl, 5 dwg

Description

 The invention relates to the field of technology for the manufacture of hollow articles by inflation in molds with moving parts of preforms preformed by extrusion from polymer materials in a plastic state and can be used in the manufacture of small-piece containers in the form of bottles, cans, cans, etc.

 The prior art in this area is characterized by the installation for the manufacture of hollow plastic products according to the patent RU 2083370 C1 B 29 C 49/06, 1997, containing an extruder with a cast head, a rotary positioning mechanism inside the assembly with interlocking half-molds for the duration of the technological operations, stationary and movable horizontal direction, equipped with a temperature control system.

 The movable half-molds are mounted on a plate mounted on guides and connected to a pneumatic actuator kinematically connected with a rotary positioning unit located between the clampable half-molds.

 The rotary turning unit is equipped with technological mandrels equipped with compressed air supply for inflating the formed semi-finished product to the finished product.

 The installation is characterized by the presence of an additional working position of the rotor for thermostating of the formed semi-finished product, located between the injection and blowing positions, which ensures the technological mode of processing and structuring of the material to improve the quality of products.

 However, the workpiece that has cooled down after thermostating and transferring to the position of inflation by air on the mandrel of the rotor assembly with diluted half-forms must be reheated to a controlled temperature, which ensures the necessary fluidity of the material, which is not technologically and energy-intensive.

 In addition, the disadvantages of the described installation are a continuation of its advantage: the common drive for closing the half-molds at all working positions leaves practically no gap between them in the limiting operation of casting the polymer melt, therefore, it is necessary to remove the layer of air from the inflation mold that prevents the product from adhering to its profile during inflating.

 In the practical implementation of the installation, a vacuum system for suctioning air from the mold when inflating the billet is used by analogy, which requires additional technical and material costs, complicates the design and commissioning.

 The noted drawbacks are eliminated in the device for the manufacture of hollow thermoplastics by blow molding according to patent RU 2096176 C1, B 29 C 49/04, 1997, which contains a frame bed supporting an electrically heated extruder with a forming head, under which a horizontal knife of the piece cutting mechanism is placed blanks from an endless tubular semi-finished product, and a nozzle for supplying technological air to the mold, consisting of lockable half-molds mounted on movable platforms kinematically connected with pneumatic cylinders positioning.

 Two forming mechanisms of sequentially alternating action are duplicated in the machine, which allows overlapping auxiliary time for workers and increasing productivity. Each forming mechanism is made with the possibility of alternating reverse rotation in the vertical plane from an autonomous drive, made in the form of two horizontal platforms symmetrically located on opposite sides of the extruder head with vertical supporting walls.

 The platforms are connected to the drive by means of pivotally mounted on one side on the vertical walls, and on the other hand, supported by a bed of two parallel-mounted rocker pairs whose axes lie in horizontal intersecting planes.

 The positioning drive of the molds is made in the form of two reversible pneumatic cylinders placed under the extruder head with rods directed oppositely to each other at the same angle to the horizontal plane, each of which is pivotally connected to the corresponding rocker arm pairs.

 On the body of the extruder is installed with the possibility of horizontal movement, the mechanism of pieces of piece billets carrying a heated knife.

 Two half-forms of each platform through an adjustable lever-crank system of closing forces are connected to the axial displacement drive.

 In one of the half-molds, a blowing needle (nozzle) is installed for supplying the process air for blowing it through the wall of the tubular billet clamped in the mold.

 The half-molds have a forced convection cooling system mounted inside.

 A disadvantage of the known machine is the complex kinematics of the crank-lever system of the mechanisms for positioning the molds in a given interaction sequence, which requires precision precision in the manufacture of their structural elements and joints, precise adjustment and commissioning, which increase its consumer cost and operating costs.

 The inflation of the tubular billet and the size in the product profile through the needle nozzle mounted on the side of the half-molds determines the increase in the process air pressure during the blowing time, because the fluid cooled from the inside decreases the flow rate, since the processed semi-finished product cools faster than it swells.

 At the same time, it does not seem practically possible to obtain a given small profile of the product, for example, an exact thread under the cover, which is not fully formed due to the fact that the neck prematurely acquires structural strength and does not inflate further.

 It should be noted that through the needle nozzle the process air is slowly removed at the end of the product inflating operation, which increases the duration of the working cycle and reduces the productivity of the machine.

 In the inflation scheme, an additional mechanism is required for pushing out the molded products and oriented automatic unloading of them onto the conveyor.

 More perfect is a device for the manufacture of hollow products from thermoplastics according to the invention SU 1523262, B 29 C 49/00, 1989, which, for most of the matching features and technical nature, is selected as the closest analogue to the proposed one.

 This extrusion blow molding machine is designed for the manufacture of hollow products from granules of a thermoplastic material and contains a frame bed supporting an electrically heated extruder with a head forming an endless tubular blank, under which a mechanism for separating a piece blank is placed, a vertically movable nozzle (nipple) for supplying process air to the press -form, consisting of lockable half-molds mounted on mounting plates (brackets) associated with a positioning drive, and a removal mechanism flea, including a figured knife. Parallel to the half-molds, the product grips are mounted symmetrically to the closing plane, spaced apart by a positioning step of the drive pneumatic cylinder.

 Clamping clamping drives are rigidly fixed to the bed in the discharge zone.

 The rapid supply of process air through the axial nozzle allows expressively inflating the workpiece into a full predetermined profile, after which it is possible to complete cooling of the formed product from the outside by convective heat removal through the mold, and then quickly release pressure at the end of the operation.

 The design of the machine provides a combination of the time taken at two positions in the operations of the product manufacturing cycle: loading a piece of blank into the mold, combining it with the nozzle and inflating, and on the other, bilateral fixation and cutting of the flake, its removal and unloading of the finished product.

 The common pneumatic cylinder for positioning the closed half-molds and the nozzle nipple provides lateral movement of them on the rollers in the horizontal plane by a step up to the spatial alignment of the clamps with the grippers at the unloading position, which allows for simultaneous inflation of the workpiece and removal of the burr of the previously formed product from the grippers from above and from below by means of mounting clamp plates.

 However, the disadvantages of the known machine include the increased kinematic closing forces of the half-molds, which, by definition, exceed the inflation pressure from the inside of the mold, the opposite direction, which determines the increased mass of the device, large production energy consumption and limited service life due to the rapid wear of the loaded movable joints of the machine drives.

 It is unreliable to force the tear-off mechanism to deliver a piece of billet in the plastic state of its material that does not have frame strength, which, in turn, does not guarantee automatic compaction of the mold and, as a consequence, the required dimensional accuracy and the given shape of the finished product.

 The machine is characterized by low functional reliability, because the continuously falling hot end of the endless tubular semi-finished product formed by the extruder head adheres to the lips of the separation mechanism of the piece blank, stretches when forced to the mold and then deviates to the periphery when they are bred. In these cases, emergency stops of the aggregated machine are necessary to remove the deformed part of the semi-finished product manually, clean the jaws and apply a preservative lubricant to their surface, which reduces productivity, increases material consumption and increases the consumer cost of products.

 It is difficult to obtain an accurate and high-quality cut of the flake of an equal-necked neck of a formed container product with dynamic transverse feeding of a horizontal knife; moreover, in the known construction it is impossible to remove the clog fixed in the clamps along the concave spherical profile of the bottom of the bottle.

 Unoriented unloading by ejection when cutting off the burden of finished products of food and medical containers is unacceptable by sanitary standards, while mechanical damage to the surface of the non-cooling wall material is possible, which increases the marriage from the loss of presentation of the product.

 The technical result of the proposed utility model is to increase the functional reliability of the molding machine, simplifying its design and improving the quality of manufactured packaging products.

 The required technical result is achieved by the fact that in a known extrusion blow molding machine for the manufacture of hollow articles from a thermoplastic material containing a frame bed supporting a heated extruder with a tubular endless blank forming a head, under which the mechanism for separating a piece blank is placed, a vertically movable nozzle for supplying a technological air into the mold, consisting of lockable half-molds mounted on mounting plates associated with air positioning cylinders the part of the mold closing plane, the grips of the molded products spaced from the half-molds by the positioning step, and the flap removal mechanism according to the invention, the vertically movable nozzle has a gage calibrating the neck of the product, adjustable in height, and axially mounted to the grips of the molded products made in the form of symmetrical half rings rigidly connected to the mounting plates of the corresponding half-forms, while the mechanism for separating the piece blank includes a two-arm lever of the first kind, on the larger shoulder of which it closes a double-edged rhombic knife is captured, and the smaller shoulder is connected to the rod of the drive cylinder pivotally mounted on the bed, and the drive cylinders of the mounting plates are mounted opposite to the center on autonomous synchronized positioning pneumatic cylinders along the locking plane, the pneumatic cylinder rods are longitudinally mounted on the bed, and on each half-mold with trapezoidal protrusions are made on both sides of the mold clamping plane, mating in pairs along the clamping plane under the closing cones, pivotally mounted Oval on the rods of pneumatic cylinders rigidly connected to mounting plates, as well as the flap removal mechanism, it contains a horizontal triangular-shaped neck knife and a steel blade made in the form of an arch, a congruent bottom surface of the product, and mounted on a lever that swings along the clamping plane in groove box-shaped slope unloading.

 Distinctive features made it possible to increase the reliability of functional units and mechanisms by simplifying the kinematic scheme of a machine with plane-parallel positioning of mounting plates bearing half-forms and on which symmetrical half rings of product grips are additionally fixed, and due to the combination of technological operations in space and time at three positions, and also provide the required accuracy and specified quality of the manufactured packaging products of the expanded nomenclature.

 When positioning the mold, the autonomously movable conical nozzle self-installs in the upper end of the tubular billet, sealing it with smooth tension, and its vertically moved calibrating girdle provides precise adjustment of the thinning of the wall of the flake to a possible minimum to reduce elastic resistance during subsequent cutting to obtain the necessary cleanliness of the finished end products at a given height.

 The installation of the nozzle with the product grips axially fixed on the mounting plates made it possible to separate the closing operations of the half-molds, loading the piece blank into the mold from the autonomous nozzle supply for sealing the mold with the simultaneous thinning of the wall of the neck of the bottle, the latter being carried out at an additional intermediate position, which is carried out in the same dimensions of the device and in parallel in time with other operations, without increasing the duty cycle.

 In this case, the nozzle performs additional functions: an interoperational holder of the formed product for moving into an annular grip when positioning the movable mounting plates and the subsequent automatic oriented unloading of the product into a box-shaped slip when the nozzle is tilted up.

 The box-shaped shape of the unloading slope provides vertical stability to a number of bottles in it during discrete pushing by closed grippers when another product is fed to remove the burr.

 Placing synchronized drives for positioning mounting plates with functional mechanisms on the periphery of the machine ensured the compactness of the aggregated device.

 The placement of geometrically closing cones on both sides of the mold along the locking plane, which mate with trapezoidal protrusions on its half-forms, with a slight taper (about 3 degrees to the axis), which is much larger than the friction angle of the mating materials - 15 degrees, provides an additional uniform force closure self-braking molds of these symmetrical conical locks, without special power cylinders and mechanisms. This allows the actuators to move the closing cones on the common mounting plates.

 The implementation of the grips in the form of half rings for the product in the proposed structural and structural relationship with the mold, nozzle and box-shaped slime allowed for oriented automatic shock-free unloading of finished products having the bearing strength of the cooled material.

 The implementation of diametrically located closing cones, mating with trapezoidal protrusions on the mold, creates their geometric closure during self-braking of this wedge connection, which reduces the clamping force by several orders of magnitude (500 versus 30,000 N in the prototype).

 The rhombic shape of a double-edged knife for separating a piece of workpiece allows you to use it again with reverse movement, and by varying the shoulders of the drive lever of the first kind, you can set the necessary speed and force to cut the workpiece without deviating it.

 Therefore, each essential feature is necessary, and their combination in a stable relationship is sufficient to achieve the novelty of quality as an effect of the amount inherent in the signs of disunity.

The essence of the proposed utility model is illustrated in the drawing, which shows:
figure 1 - diagram of the machine;
figure 2 - technological scheme of positioning;
figure 3 is a view along arrow a in figure 1;
figure 4 - nozzle;
figure 5 is a diagram of the removal of the flare.

 The extrusion blow molding machine for the manufacture of small-piece containers made of thermoplastic polymer, such as polyethylene, polypropylene, is a complex device with rigidly interlocked functional elements of the combined action structure.

 The machine bed 1 is a frame-shaped structure on which an electrically heated extruder 2 (Fig. 1) with a forming head 3, a mechanism for separating a piece of workpiece 4, horizontal rods 5 (Fig. 3) of positioning cylinders 6 along the closing plane 7, symmetrically mounted, are fixed , pneumatic cylinder 8 for vertical displacements of the nozzle 9 for supplying technological compressed air (Fig. 4), mechanisms for cutting off the flake (Fig. 5) and box-shaped skliz 10 for unloading finished products.

 The mechanism for separating a piece of blanks 4 is located under the head 3, forming an endless tubular semi-finished product, and includes a two-arm lever of the first kind, on the larger shoulder of which a double-edged rhombic-shaped knife 12 is fixed, and the smaller shoulder is movably connected to the rod 13 of the drive cylinder 14, pivotally mounted on the bed 1.

 On the bed 1, on both sides of the closure plane 7, on the periphery of the machine, guide rods 5 of positioning pneumatic cylinders 6 are longitudinally fixed, on which drive cylinders 15 are mounted opposite to the center, carrying mounting plates 17 on the rods 16.

 On the plates 17, the half-molds 18 are symmetrically strengthened, which together form a mold for inflating plastic tubular blanks along a given container profile, and grippers 19 (FIG. 3) of the molded products.

 On each half-mold 18, trapezoidal protrusions 20 are made under the closing cone 21, pivotally mounted on the rod 22 of the pneumatic cylinder 23, rigidly connected to the mounting plate 17 on both sides of the mold closing plane 7.

 The half-molds 18 are equipped with circulation channels for the coolant — cooling water (not shown).

 Above the grippers 19, in the clamping plane of the mold, a movable nozzle 9 is mounted, equipped with a calibrating girdle 24 and mounted on the hollow stem 25 (Fig. 4), which communicates with the compressed air supply system, a technological agent for inflating the tubular workpiece. The nozzle 9 is installed with the possibility of axial movement relative to the rod 25 by means of a thread with a fine pitch, the position of which is fixed by a lock nut 26.

 Behind the nozzle 9, at a distance equal to the distance between the axes of the half-molds 18 and grippers 19, are installed (Figs. 3 and 4): at the height of the end of the neck of the bottle, a horizontal knife 27 and below it the swing axis 28 of the lever 29 carrying an arched double-edged knife 30 from steel sheet mounted in the groove of the slice 10 unloading the finished bottles (figure 5).

 The knife 27 has a triangular shape, symmetrical to the longitudinal axis of the bottle in the clamps 19 at this position, and is equipped with a drive cylinder 31.

 The lever 29 of the knife 30 is pivotally connected to the rod 32, movably mounted on the frame 1 of the pneumatic cylinder 33. The knife 30 has a profile of the bottom of the bottle and mates with it when swinging along the clamping plane of the clamps 19 (figure 5), in the slip groove 10 of the box-shaped discharge.

 The machine operates as follows. The following is an example of sequential actions and transformations from one blank to the finished product, in particular 0.5 liter ketchup bottles.

 In the initial position, the mounting plates 17 (FIGS. 2, a and 3) are located away from the closing plane 7 of the actuators fixed to them, the positioning cylinders 6 are at the top, the closing cones 21 are separated into a position peripheral relative to the half molds 18, and the nozzle 9 (FIG. 4) raised to the drive cylinder 8, the horizontal knife 27 is retracted from the closing plane 7 (to the left according to the drawing), and the lever 29 (Fig. 5) is in the extreme swing position.

 The granular polymer material molten by the heat of the converted electricity is pumped by the screw of the extruder 2, extruded through the forming head 3 in the form of an endless tubular semi-finished product.

 When the specified length of the semi-finished product, controlled by a proximity sensor, is reached, compressed air is transferred in the cylinders 15 (Fig. 3) and 14 (Fig. 1), the rods 16 and 13 respectively move to the plane 7 of the closure of the plate 17 and the lever 11 is swiftly rotated. piece billet, which, under the action of gravitational forces, falls into the interlocking half-molds 18, where it is clamped by them below (Fig. 2, b).

 Then, with the rods 22 of the pneumatic cylinders 23, the cones 21 on both sides of the mold are mounted on the combined protrusions 20 of the closed half-molds 18: geometric and force (self-braking) closure of the mold is practically monolithic.

 At the same time, compressed air is passed in the positioning cylinders 6, which are lowered along the rods 5 to the extremely low position in FIG. 3, moving the plates 17 (FIG. 2, c).

 Next, the nozzle 9 under the action of the rod 25 (figure 4) of the cylinder 8 is lowered to the mold and self-installs inside the workpiece, dipping with a gauge belt 24 the wall of the bottle neck area and sealing it, thereby sealing the internal volume of the workpiece being processed.

Then the compressed process air through the hollow stem 25 and nozzle 9 with a pressure of 4. ..6 atm is fed into the workpiece, blowing its walls along the mold-forming profile of the mold, thinning the walls from a thickness of 1.5 to 0.3 ... 0.5 mm Under this pressure, the billet is held for 4 ... 6 s with forced convective heat removal by means of water circulating in the channels of the half-molds 18 with a temperature of + 6-10 ^o C to complete the polymerization and structural transformations in the material with active cooling. As a result of inflating, the preform takes on the desired shape, and when cooled, the bearing strength of the container structure, in particular the bottle for closing the ketchup.

 After that, the pressure inside the mold is relieved and the rods 22 of the pneumatic cylinders 23 are returned by the closing cones 21 to their original position, releasing the aligned protrusions 20 on both sides of the half-molds 18, and the plates 17 by the cylinders 15 are relegated to the extreme position from the closing plane, freeing the polymer bottle, which neck is held on the nozzle 9 (Fig. 2, g).

 Then air is transferred in the cylinders 6, which, along the guide rods 5, lift the plates 17 with actuators up to their initial position (Fig. 2, a), while the grippers 19 are installed under the nozzle 9 opposite the molded bottle hanging on it.

 In the next cycle of closure, the grippers 19 fix this bottle, and the nozzle 9 moves upward by the rod 25 of the cylinder 8, freeing its neck (Fig. 2, c, 9).

 By feeding the plates 17 to the lowest position, the bottle grippers 19 are transferred to the unloading side 10 to the edge circumcision position (FIGS. 3 and 5), where by the transverse movement of the horizontal knife 27 under the action of the drive cylinder 31, the neck of the bottle is cut to height and reciprocating the movement of the rod 32 of the pneumatic cylinder 33 with an arched knife 30 cuts off an area around the bottom spherical part of the bottle.

 The load distribution on two inclined cutting blades of a centrally mounted triangular horizontal oriented knife 27 reduces the elastic deformation of the walls of the neck, which ensures the accuracy of the cut and the size of the bottle height.

 In the swing cycle of the lever 29, an arched double-edged knife 30, congruent with the bottom surface of the bottle, resting on the slide 10 and fixed in the grippers 19, cuts off the flush formed when the workpiece is clamped by half-molds 21 to inflate.

 When the mounting plates 17 return to their initial position, the grippers 19 release the finished product, leaving the bottle in the slime 10, and the next course of the plates 17 in the extreme lower position in Fig. 3, the closed grippers 19 push this bottle along the slide 10 for subsequent filling with the product and closing the container.

 Thus, for each cycle of the reciprocating movement of the positioning cylinders 6 of the mounting plates 17 with the actuators fixed on them at three consecutive working positions of the machine, the finished product is formed, because the clamping operation of the workpiece in the half-molds 18, its inflating in a closed mold, cutting burrs in grabs 19 and unloading in skliz 10 are carried out in parallel, combined in time.

 The proposed technical solution is a stable unity of design and functionality, provided by a set of essential features, the actuators of which operate in parallel-sequentially in a rigid mechanical connection of three working positions, equipped with autonomous drives with track control system.

 The machine is characterized by simple kinematics, reliable operation, ease of setup and maintenance, it can be easily reconfigured to other standard sizes of manufactured polymer containers.

 A comparative analysis with identified analogues of the prior art, from which the proposed technical solution does not explicitly follow for a specialist in mechanical engineering, showed that it is not known, and taking into account the possibility of industrial reproduction of a machine for manufacturing hollow products by blowing out plastic materials, it can be concluded that the criteria are met patentability.

Claims (2)

 1. An extrusion blow molding machine for the manufacture of hollow articles of thermoplastic material, comprising a frame bed supporting a heated extruder with a tubular endless blank forming a head, under which a mechanism for separating a piece blank is placed, a vertically movable nozzle for supplying process air to the mold, consisting from interlocking half-molds mounted on mounting plates associated with positioning pneumatic cylinders along the mold closing plane, molded product grips spaced apart from the half-molds by a positioning step, and a flake removal mechanism, characterized in that the vertically movable nozzle has a gage calibrating the neck of the product, adjustable in height, and mounted axially to the grips of the molded products, made in the form of symmetrical half rings, rigidly connected to the mounting plates of the corresponding half-form, while the mechanism for separating a piece of workpiece includes a two-arm lever of the first kind, on the larger shoulder of which a double-edged rhombic-shaped knife is fixed, and the smaller shoulder is connected but with the rod of the drive cylinder pivotally mounted on the bed, and the drive cylinders of the mounting plates are mounted opposite to the center on autonomous synchronized positioning cylinders along the clamping plane, the piston rods are longitudinally mounted on the bed, and on each half-mold on both sides of the clamping plane of the mold trapezoidal protrusions, mated in pairs along the locking plane under the closing cones, pivotally mounted on the rods of pneumatic cylinders, rigidly connected with mounting mi plates.  2. The machine according to claim 1, characterized in that the flap removal mechanism comprises a horizontal triangular-shaped neck knife and a steel blade made in the form of an arch, a congruent surface of the bottom of the product, and mounted on a lever that swings along the plane of closure of the lever into the groove box-shaped skliza of unloading.

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