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EP-4587254-B1 - PARISON FORMING HEAD GROUP WITH VARIABLE INTERAXIAL DISTANCE

EP4587254B1EP 4587254 B1EP4587254 B1EP 4587254B1EP-4587254-B1

Inventors

  • GIACOBBE FERLISI, Davide

Dates

Publication Date
20260506
Application Date
20230911

Claims (15)

  1. Forming group for forming a plurality of tubular parisons made of plastic material for a blow-moulding machine, comprising: a support (230), fixed during use; a first forming head (10A) and a second forming head (10B) mounted on the support (230) in a position alongside each other in a longitudinal direction (X-X); wherein each forming head (10A,10B) is configured to dispense a tubular parison (1,2) made of plastic material along a respective vertical dispensing axis through a bottom dispensing mouth and comprises a respective inlet (322i) for entry of the plastic material to be dispensed into the forming head (10A,10B); a supply source for supplying the plastic material, in particular a common inlet (310a) for supplying the plastic material; a mover assembly, arranged and configured to move the forming heads (10A,10B) in translation towards/away from each other in the longitudinal direction (X-X) so as to vary the interaxial distance between the dispensing axes of the forming heads; and connection means which connect the plastic material supply source (310a) to the inlet of the first head (10A) and to the inlet of the second head (10B) and which are configured to maintain the connection upon variation of the interaxial distance between the forming heads (10A,10B). characterized in that the connection means comprise: a first duct (455) communicating with the supply source, in particular with the common inlet (310a), a first compensator joint (451) which connects the first duct (455) to the inlet of the first head (10A) and is configured to expand/retract upon variation of the interaxial distance between the dispensing axes of the forming heads, so as to maintain the connection between the plastic material supply source (310a) and the respective inlet of the forming head (10A, 10B); and/or a second duct (455) communicating with the supply source, in particular with the common inlet (310a), a second compensator joint (452) which connects the second duct (455) to the inlet of the second head (10A) and is configured to expand/retract upon variation of the interaxial distance between the dispensing axes of the forming heads, so as to maintain the connection between the plastic material supply source (310a) and the respective inlet of the forming head (10A, 10B).
  2. Forming group according to Claim 1, characterized in that it comprises a reference block (310), which is fixed during use, in particular to the support (230), and which is arranged between the first and second forming heads and includes said plastic material supply source (310a), said first duct (455) for supplying the material and said second duct (455) for supplying the material.
  3. Forming group according to Claim 2, characterized in that each compensator joint (451,452) is configured to expand/retract upon variation of the relative position in the longitudinal direction between the respective forming head (10A,10B) and the reference block so as to maintain the connection between the plastic material supply source (310a) and the respective inlet of the forming head (10A,10B).
  4. Forming group according to the preceding claim, wherein each compensator joint (451) comprises a first element fixed to the reference block (310) and a second element arranged at the inlet (322i) of the forming head and movable therewith in the longitudinal direction, one of said first and second elements comprising a sleeve (451a) and the other element comprising a bush (451c), the sleeve being coaxially coupled sealingly with the bush (451c) so as to allow relative displacement thereof while maintaining the fluid connection between the reference block (310) and the inlet for entry of the material in the forming head.
  5. Forming group according to the preceding claim, wherein each sleeve (451a,452a) has a respective annular shoulder (451b,452b) designed to create a gap with the respective bush (451c,452c), said gap being designed to be filled with material to create a seal for preventing leakage of the material from the compensator joint (451,452).
  6. Forming group according to one of the preceding claims, characterized in that each forming head (10A, 10B) includes a respective supply group (200A; 200B), comprising a respective block (321; 322) which has the respective inlet for the material, translating integrally with and connected to a distribution chamber (210) designed to supply the plastic material to the respective dispensing mouth of the forming head.
  7. Forming group according to one of the preceding claims, characterized in that it comprises a first flange (211) and a second flange (221) which are supported on a longitudinal/transverse plane of the fixed support (230) so as to allow a relative translation of the flanges (211;221) in the longitudinal direction (X-X), and in that each of said flanges (211;221) translates integrally with a respective forming head, in particular with a respective block (311,321) of the supply group of the forming head.
  8. Forming group according to the preceding claim, wherein the fixed support is in the form of a plate (230) having an internal cavity passing through in the vertical direction, with an upper plate surface which defines said longitudinal/transverse plane, and wherein each flange (211,221) has sliders resting on the plate (230) and free to move in the longitudinal/transverse plane.
  9. Forming group according to one of the preceding claims, characterized in that the movement assembly comprises: -- driven rotating means (313,314) coupled to the first forming head and to the second forming head, in particular to the first and second blocks (321,322) of the first and second heads, such that the rotational movement of the driven means causes a movement in the longitudinal direction of the forming heads (10A,10B) with respect to the fixed support, towards/away from each other in the longitudinal direction; -- a drive element, preferably consisting of a driving gear (333), designed to be connected to a drive system for generating a rotational movement; -- a transmission mechanism (331,332) for transmitting the movement from the drive element to the driven means.
  10. Forming group according to one of the preceding claims, characterized in that said driven means include a first longitudinal shaft (313) and a second longitudinal shaft (314), the opposite ends (313a,313b;314a,314b) of each shaft having a respective thread (315a,315b) with opposite thread direction to the thread of the other end, said threads being designed to cooperate with respective female threads fixed to the first block (321) and to the second block (322), so that rotation of the shafts causes a symmetrical translation of the first and second heads (10A,10B), in opposite senses along the longitudinal direction.
  11. Forming group according to the preceding claim, when dependent on Claim 3, wherein the driven shafts are inserted through the reference block (310) so as to be axially fixed but allowed to rotate with respect thereto; wherein, preferably, the two driven shafts are arranged opposite each other along a diagonal of the reference block (310).
  12. Forming group according to the preceding claim, wherein the transmission mechanism comprises a respective pinion (331) mounted on a respective end (313a,314a) of the driven shafts (313, 314) and an idle gear (332) which meshes with the pinions (331) and with the drive element so as to transmit the rotational movement from the drive element to the driven shafts and synchronize the rotation of the two driven shafts (313,314).
  13. Forming group according to one of Claims 9 to 12, wherein the movement assembly further includes guiding means (311,312) for guiding the displacement of the forming heads (10A,10B), in particular of the blocks (321;322) of the forming heads, preferably comprising a first sliding and guiding bar (311) and a second sliding and guiding bar (312), fixed to the reference block (310) from which they project in both senses of the longitudinal direction; the respective opposite ends (311a,311b;312a,312b) of each guiding bar (311,312) being inserted inside corresponding holes (321a,321b;322a,322b) of the first head, in particular of the first block (321), and of the second head, in particular of the second block (322), respectively.
  14. Forming group according to one of the preceding claims, wherein each forming head comprises a respective die group (100A,100B), with a respective female die (110,120) which defines the dispensing mouth, wherein a male element is coaxially inserted inside each die (110,120) and through the dispensing mouth so that, by varying a relative position in the vertical direction between the die (110,120) and the male element, the opening of the dispensing mouth and therefore the thickness of the dispensed parison (1,2) is adjusted.
  15. Forming group according to the preceding claim, wherein a respective electric actuator (400A,400B) designed to perform an adjustment of the thickness of the parison of the respective forming head (10A,10B) is supported by the respective support flange (211,221) and arranged so as to displaceably actuate in the vertical direction either the male element or the die in order to vary the opening of the dispensing mouth.

Description

The present invention relates to a group for forming a plurality of tubular parisons made of plastic material for a blow-moulding machine, comprising at least a first and a second forming heads with a vertical axis for forming a respective parison and a group for adjusting the interaxial distance between the forming heads. It is known in the technical sector of packaging liquid products and the like that there exists the need to produce plastic containers suitable for this purpose. It is also known that said containers are formed in suitable blow-moulding machines provided with forming heads which are designed to dispense a respective tube of plastic material - known as a "parison". Each forming head is arranged above an associated blowing seat of a blowing mould, formed by two half-moulds displaceable between two different opening/closing positions for capturing/releasing the dispensed parisons which are blown inside the closed mould. It is also known that in conventional blow-moulding machines with several heads for forming respective parisons said heads are arranged with a fixed interaxial distance between the dispensing axes of each head, while the blowing mould which arrives underneath the forming heads may have seats with an interaxial distance which is varied depending on the dimensions and/or shape of the final containers which are to be obtained. In order to vary said interaxial distance it is therefore necessary to change the entire group of forming heads in order to adapt them to the different production format. This results in a long machine downtime for allowing the necessary replacement operations, with a consequent reduction in the productivity and increase in both the final costs of the single containers and the general management costs. In addition, it is necessary to maintain a storage facility which is always active and stocked with the different forming heads for the necessary replacement operations. AT 318 898 and GB1336504A describe a multi-head extruder according to the preamble of claim 1 for use with a plurality of cavities in a mould, wherein the body of each extrusion head is mounted so as to rotate about an axis substantially coinciding with the longitudinal central line of a passage through which the plastic material is supplied to the body of each extrusion head, so that the distance between the centres of the dies of the extrusion heads may be adapted to the centres of these cavities of the mould by rotating the extrusion heads about said axis. In this known extruder, the body of each extrusion head is supported by an intermediate element mounted on the body of an extrusion press by means of a collar rigidly fixed to a body of the press. The aforementioned intermediate element is free to rotate, inside said collar, about the longitudinal central line of the passage through which the plastic material is supplied by the extruder and means are provided for adjusting the configuration of the extruder body and therefore the rotation position of the intermediate element inside the collar. The known adjustment by means of rotation, while being effective for avoiding irregularities in the thickness of the parison, does not however provide satisfactory results as regards the adaptation to different shapes and sizes of the moulds. Further examples of machine known of the prior art and according to the preamble of claim 1 are known from IT BO2008 0731. The technical problem which is posed therefore is that of providing forming heads for blow-moulding machines which are able to adapt to different shapes and sizes of the blowing moulds. One particular object of the present invention is to allow a variation of the interaxial distance between the dispensing axes of the parison forming heads without the need for time-consuming replacement of the said heads when there is a variation in the shape and/or interaxial distance between the seats of the blowing mould during production. These results are obtained according to the present invention by a forming group according to the features of Claim 1. According to one aspect of the invention, the forming group for forming a plurality of tubular parisons made of plastic material for a blow-moulding machine comprises a fixed support, a first forming head and a second forming head, arranged alongside each other in a longitudinal direction, and a supply source for supplying the plastic material. Each forming head is configured to dispense a tubular parison made of plastic material along a respective vertical dispensing axis through a bottom dispensing mouth. A movement assembly is configured to cause a relative movement of the forming heads in translation along the longitudinal direction so as to vary the interaxial distance between the dispensing axes of the forming heads. Connection means connect the plastic material supply source to a respective inlet for entry of the plastic material to be dispensed into the forming head and maintain the connection