IMPROVED GRIPPERS FOR HANDLING PREFORMS

Abstract: Preform gripper comprising a handling arm (1) and a preform support plate (2) that has at an extremity thereof a semi-circular aperture (7) that is adapted to accommodate a cylindrical portion (28) of the collar of the preform. Hinged on said plate there are provided two parallel side gripping members (5, 6), two end portions of which (13, 14) are in the shape of an arc of a circle and are adapted to elastically move closer to each other up to a pre-established position. The gripper is adapted to enable said cylindrical portion (28) of the collar of the preform to be fitted into and removed from, with a snap-like action, said semi-circular aperture (7) by pressing and pulling, respectively, the preform against two opposite, elastically enlargeable outer edges (31, 32) of said two side gripping members (5, 6).

Description: IMPROVED GRIPPERS FOR HANDLING PREFORMS DESCRIPTION The present invention refers to a gnpper adapted to most effectively and m a semi-automatic manner seize, le hold firmly, and release cylindrical bodies Although for reasons of greater descriptive simplicity reference will be made to preforms of thermoplastic material used in the production of containers in the following description, the present invention shall of course to be understood as applying also to other cylmdncal bodies used in different applications, as far as they do not depart from the scope of the appended claims Gnppers for seizing and holding firmly preforms are known which compnse a handling arm, a pair of symmetncal, elastically diverging members, and connecting means between said arm and said symmetncal members The latter are shaped so as to form a concavity whose opposite arms are arranged and sized in such a manner as to enable a cylmdncal portion of the collar of a preform to be inserted therein by means of a simple pressure of said collar against the outer portions of said concavity, which owing to the action of such a pressure, are caused to be enlarged by such an extent as adequate to enable the collar of the preform to slip into said concavity in which it is then retained However, such an operation and the particular type of gnpper used to carry it out, have following drawbacks - the preform may be subjected to both axial and transversal stresses; in order to be able to withstand such stresses, said symmetrical members must possess a considerable elastic strength However, the required extent of said elastic strength brings about a considerable fnction between said arms and the outer surface of the preform, which therefore undergoes a slight abrasion, considering that it is made of thermoplashc matenal that is only slightly heated up In a situation of large-scale series production, this fact practically causes tiny particles, le the so-called "flour" of the plastic material involved to be produced, which then contaminates the adjacent parts of the plant and disturbs the regular flow of the subsequent process operations and makes them inaccurate If on the other hand such an undesired effect has to be reduced, the need anses for the elastic gnpping force of said arms to be reduced Such a constraint, however, is largely known to all those skilled m the art to bring about corresponding inaccuracies m the positioning of the preform, with clear handling difficulties resulting therefrom Moreover, making gnppers provided with holding arms having a considerable elastic strength implies a production that requires a far higher extent of accuracy and, therefore, is much more expensive It is therefore a main purpose of the present invention to provide a gnpper for handling cylmdncal bodies, and m particular plastic preforms, which does away with the above described drawbacks and, at the same time, is compact, safe and reliable in its operation, and requires a simple, reliable construction based on the use of reaairy available techniques Such a type of gnpper is obtained and implemented with the charactenstics that are substantially αescnbed with particular reference to the appended claims Anyway, features and advantages of the present mvention can more readily be understood from the descnption that is given below by way of non-limiting example with reference to the accompanying drawings, in which - Figure 1 is a perspective view of a gnpper according to the present invention, - Figure 2 is a similar perspective view of a component part of the same gnpper illustrated in Figure 1 , - Figure 3 is a top plan view of the same component part illustrated m Figure 2, - Figure 4 is a view along the A - A section of the component part illustrated m Figure 3, - Figure 5 is a view along the B - B section of the gnpper illustrated in Figure 1 , - Figure 6 is a view along the A - A section of the gnpper illustrated in Figure 5, - Figure 7 is a perspective view of a partial assembly of some component parts of the gnpper illustrated in Figure 1 , - Figure 8 is a top plan view of the assembly illustrated m Figure 7 With reference to the above Figures, the gnpper according to the present invention comprises - a handling arm 1 , - a plate 2 for seizing and supporting the preform 3, - an interconnection means 4 provided between said arm and said plate and firmly joined thereto, - two symmetncal side gnpping members 5 and 6, - a cylmdncal sprmg 8 provided between corresponding extremities of said gripping members 5 and 6. Said plate 2 is provided, at an extremity thereof, with a semi-circular aperture 7 havmg such a diameter as adequate to enable it to accommodate a part of a cylmdncal portion 28 of the collar of the preform 3 It is however possible for said aperture to be given a non-circular shape, and to be for mstance m the shape of an even non-circular arc mstead, as far as it proves anyway capable of gettmg coupled with an adequate portion of the collar of the preform It is furthermore provided, m correspondence of the opposite side edges thereof, with two grooves 9 and 10 adapted to accommodate a respective side gripping member 5 and 6 Said side gripping members 5 and 6 are hinged on said interconnection means 4 by means of appropnate pivotally connecting means (pivots, pms and the like) and, smce said mterconnectmg means 4 is firmly jomed with said plate 2, it ensues that said siαe gripping members 5 and 6 are substantially attached to said plate, while however bemg able to slightly rotate with respect to said plate thanks to said pivotally connectmg means getting engaged mto respective appropnate holes 11 and 1 provided m said side gripping members These members are provided at the respective extremities 13 and 14 located m correspondence of said semi-circular aperture 7, with two respective arcs of a circle 15 and 16 On the opposite side of said extremities 13 and 14 there is provided a cylmdncal compression spring 8 which, as such, tends therefore to keep said extremities 13 and 14 closed, or at least approached to each other, said extremities bemg anyway limited m their separation gap by the fact that the inner sides 1 , 18, respectively, of said extremities 13 and 14 are adapted to abut agamst the outer edges of a central relief 20 of said support plate 2, as this is illustrated m particular m Figures 1 and 5 Said side members are adapted to move mto at least a resting position and at least a working position, the restmg position is determined by the action of the sprmg 8 that tends to move said extremities 13 and 14 closer to each other up to the pomt at which the stoppmg action of said central relief 20 comes mto play In this resting position, said arcs of a circle 15 and 16 move mto an arrangement as illustrated symbolically m Figures 7 and 8, le - they identify a circle whose diameter D is slightly smaller than the diameter H of the semi-circular aperture 7, and - the outer edges 21 and 22, respectively, of said arcs of a circle 15 and 16 are located at a distance M that is smaller than said diameter D and also smaller than the outside diameter of the preform The working position is illustrated m Figures 1 , 5 and 6 it can be noticed that the preform is mserted within said semi-circular aperture 7, where it is retained by said arcs of a circle 15 and 16 which are pressed agamst a cylmdncal portion of the collar of said preform by the effect of the elastic action of the sprmg 8 and also owmg to the fact that the diameter of said collar is greater than the diameter D of said arcs of a circle m the restmg position thereof, so that, when the preform is so mserted, said arcs of a circle are deflected outwardly, thereby causmg the preform to be held firmly In an advantageous manner, said preform retaining action can be further improved if said central relief 20 is provided, m correspondence of the edge thereof which is adjacent to said semi-circular aperture 7 with abutting means m the shape of an arc of circle 23, as illustrated in particular in Figure 2, which are adapted to get fittingly into coupling with a cylindrical portion of the collar of the preform, as illustrated in Figures 1, 5 and 6. In this way, the combined effect of said side members 5 and 6 so closing elastically and said abutting means 23 moving so into coupling against the collar of the preform causes the latter to be held firmly, in an elastically releasable manner, against the described gnpper. It is in fact sufficient for an appropriate portion of the collar of the preform to be pressed in an axial direction into said semi-circular aperture in order to cause said side gripping members to move apart by an adequate extent, thereby allowing for the preform to slide into said semi-circular aperture. When said side gripping members are then so moved into such a position, they tend to move back into their resting position, owing to the action of the spring 8, thereby causing the collar of the preform to be held firmly. It should be particularly noticed that, with such an embodiment, the side stresses on the preform are easily neutralized by the resistance of the arms of the semi-circular aperture 7, without any consequence on the capability thereof to grip and hold the preform in a firm and efficient manner. On the other hand, the axial stresses determined by the preform being mserted in and released from the gripper may be limited to any desired extent by simply adjusting the characteristics of the spring 8 accordingly, without anyway impairing the stability and, above all, the precision of the position in which the preform is held, owing to the effect of the abutting means 23 getting so coupled. A further improvement in the way in which the preform is inserted is easily obtained if said two side gripping members 5 and 6 are provided, at the respective extremities 13 and 14, with respective edges 31, 32 with an appropriate flared shape and arranged so as to define a V-shaped or funnel-shaped configuration in view of facilitating the preform to move into self-positioning and said extremities 13, 14 to move apart under the action of even a moderate axial pressure exerted by the preform. It shall be appreciated that the description and illustrations given above with reference to the accompanying drawings have been given by mere way of exemplification of the present invention, and that a number of variants and modifications can therefore introduced thereto without departing from the scope of the present invention.

Claims: CLAIMS 1. Gnppers for preforms havmg a collar portion, compnsmg - a handling arm (1), - means (2) adapted to support and handle the preform (3), - interconnection means (4) provided between said arm and said support means and firmly jomed thereto, characterized m that - said support means (2) is formed by a plate made m a smgle integral piece that is provided at an extremity thereof with a preferably semi-circular aperture (7) adapted to move mto coupling with and accommodate a portion (28) of the collar of the preform, - there are provided two preferably symmetncal, parallel side gnpping members (5, 6) hmged on to said plate, whose two extremities (13, 14) are formed with respective contours (15, 16) adapted to be capable to move mto fittingly coupling with two respective portions (15, 16) of said collar of the preform, and are further adapted to elastically move closer to each other up to a pre-determmed position 2 Gnpper according to claim 1 , charactenzed m that said two side gnpping members can move mto at least a resting position and a working position, m which - the resting position is determined by the smallest possible separation gap (D) that can be reached between said two extremities (13, 14) when they move closer to each other up to a pre-determmed position, - and the working position is defined by the extent to which said two extremities are caused to e.astically open wide apart until the respective contours (15, 16) engage two respective portions of said collar of the preform, said contours bemg so arranged as to cause the outer edges (21, 22) thereof to dispose themselves at a distance (M) which is smaller than the distance (H) of the outer edges of said aperture (7) from each other. 3. Gripper according to claim 2, characterized in that said plate is provided centrally with a relief portion (20), wherein in said resting position thereof said side gripping members abut against respective grooves (9, 10) of said relief portion. 4. Gripper according to claim 3, characterized in that there are provided one or more elastic members that operate in a compressing mode on said two side gripping members on the opposite side of said respective estremities (13, 14). 5. Gripper according to claim 4, characterized in that said elastic members comprise a cylindrical spring (8) acting on said elastic members in contrast thereto, wherein said plate is preferably provided, on the opposite side of said extremities, with a hole (33) adapted to accommodate said spring. 6. Gripper according to any of the preceding claims, characterized in that said two side gripping members (5, 6) are provided with respective outer edges (31, 32) that are so oriented as to be able to define a funnel-shaped or V-shaped configuration adapted to facilitate the insertion of said cylindrical portion of the collar of said preform. 7. Gripper according to any of the preceding claims, characterized in that said relief portion (20) is provided, on the edge thereof which is adjacent to said aperture (7), with a step-like abutment (23) that is adapted to fittingly couple with said cylindrical portion (28) of the collar of the preform. 8. Gripper according to any of the preceding claims, characterized in that it is adapted to enable said cylindrical portion (28) of the collar of the preform to be fitted into and removed from said aperture (7), with a snap-like action, by simply pressing and pulling, respectively, said cylindrical portion against said outer edges (31, 32) capable o: widening elastically of said two side gripping members. AMENDED CLAIMS [received by the International Bureau on 16 October 2000 (16.10.00); original claims 1 and 2 amended; remaining claims unchanged (1 page)] 1. Grippers for preforms having a collar portion, comprising: a handling arm (1), support means (2) adapted to support and handle the preform (3), formed by a plate made in a single integral piece that is provided at an extremity thereof with a preferably semi -circular aperture (7) adapted to move into coupling with and accomodate a portion (28) of the collar of the preform, - interconnection means (4) provided between said arm and said support means and firmly joined thereto, two symmetrical, parallel side gripping members (5, 6) hinged on to said plate, whose two extremities (13, 14) are formed with respective contours (15, 16) adapted to be capable to move into fittingly coupling with two respective portions (15, 16) of said collar of the preform, and are further adapted to elastically move closer to each other up to a pre-determined position, one or more elastic members that operate in a compressing mode on said two side gripping members on the opposite side of said respective extremities (13, 14), said elastic members comprising a cylindrical spring (8) acting on said elastic members in contrast thereto, wherein said plate is provided, on the opposite side of said extremities, with a hole (33) adapted to accommodate said spring, characterised in that said plate is provided centrally with a relief portion (20), said resting position thereof said side gripping members being abutting against respective grooves (9, 10) of said relief portion. 2. Gripper according to claim 1, characterised in that said relief portion (20) is provided, on the edge thereof which is adjacent to said aperture (7) with a step-like abutment (23) that is adapted to fittingly couple with said cylindrical portion (28) of the collar of the preform.

Inventors: ZOPPAS MATTEO, ZOPPAS, MATTEO
Applicants: SIPA SPA, ZOPPAS MATTEO, SIPA S.P.A., ZOPPAS, MATTEO
Application year: 2000
Main classification: B29C49
IPC codes: B25J15, B29C49, B29L22