ROTATING AND TRANSLATING CAPPING HEAD WITH STATIC DRIVE ASSEMBLY

Abstract

A capping head for applying pre-threaded caps to containers includes a rotating and translating shaft, a first electric motor for driving the rotary motion of the shaft, the motor having a stator and a rotor coaxially arranged around the shaft and mounted in a stationary housing so as to be decoupled from the shaft as far as the translational motion is concerned, and a first bushing, which is mounted at one end of the stationary housing, is passed through by the shaft and is arranged to transfer the rotary motion of the rotor to the shaft. The head further includes a second bushing that is mounted at a second end of the stationary housing, opposed to the first one, to seal the internal cavity thereof also at that second end, and is passed through by the shaft that is mounted in the same bushing in a freely rotatable manner.

Claims

1. A capping head (1, 1A) for applying pre-threaded caps to containers, including: a shaft (2) movable according to a rotary motion about its axis and a translational motion along said axis; a first electric motor (5) for driving the rotary motion of the shaft (2), the first electric motor (5) having a stator (50) and a rotor (51, 51a) coaxially arranged around the shaft (2) and mounted in a stationary housing (6) so as to be decoupled from the shaft (2) as far as the translational motion is concerned; a first bushing (12), which is mounted at one end of the stationary housing (6) so as to seal the internal cavity thereof at said end, is passed through by the shaft (2) and is arranged to transfer the rotary motion of the rotor (51, 51a) to the shaft (2) thanks to the cooperation between ribs (15) provided on an inner surface thereof and grooves (14) provided on an outer surface of the shaft (2); characterised in that: the head (1; 1A) further includes a second bushing (11) that is mounted at a second end of the stationary housing (6), opposed to the first one, so as to seal the internal cavity thereof also at that second end, and is passed through by the shaft (2) that is mounted in the same bushing (11) in a freely rotatable manner; the first electric motor (5) forms, together with the stationary housing (6) and the first and second bushings (12, 11), a self-standing module for driving rotation of the shaft (2); and said module (5, 6, 11, 12) can be associated, for driving the translational motion, either with a member (41) carrying cam follower rollers (42) arranged to cooperate with a mechanical cam (104, 104a) along the whole of the path run by the head (1) during a capping operation, or with a second electric motor (200) arranged to impart the translational motion to the shaft (2).

2. The capping head (1; 1A) according to claim 1, wherein the shaft (2) is translatable jointly with a decoupling joint (40) that is mounted at the end of the shaft (2) proximal to the second bushing (11), is arranged to allow rotation of the same shaft (2) about its axis and can be fastened, in a detachable manner and so as to be jointly translatable, either to the member (41) carrying the cam follower rollers (42), or to a piston (201) that is moved by the second electric motor (200) according to a linear motion.

3. The capping head (1) according to claim 2, wherein the member (41) carrying the cam follower rollers (42) is associated with means (7, 43) for preventing, while the head (1) is advancing along the cam (104, 104a), unwanted rotary movements of the same head (1) possibly occurring during the translational motion.

4. The capping head (1A) according to claim 2, wherein the decoupling joint (40) is fastened to the piston (201) by means of a rod (202) transmitting the linear motion imparted to the piston (201) by the second electric motor (200).

5. The capping head (1A) according to claim 4, wherein the second electric motor (200) is housed inside a housing (203) that is mounted so as to be stationary relative to the head (1A), in such a way that the components of the second motor (200) are decoupled, as far as the translational motion is concerned, from the movements of the piston (201) and hence of the shaft (2).

6. The capping head (1; 1A) according to claim 5, wherein the shaft (2) has an axial cavity (20) accommodating means for driving cap-handling members carried by the same shaft (2).

7. The capping head (1; 1A) according to claim 6, wherein component-holding boxes (8; 8A) are mounted onto the stationary housings (6; 203) of the first electric motor (5) and, if provided, of the second electric motor (200), which boxes accommodate electronic components for supplying the motors (5; 200) with power and for controlling and monitoring the operations of the head (1; 1A), wherein cables (9) for the power supply and the reception and transmission of signals, data and commands from and to the components terminate at said boxes (8).

8. A capping machine (100) comprising at least one capping head (1; 1A) according to claim 1.

9. The capping machine (100) according to claim 8, comprising a plurality of capping heads (1; 1A) carried by a common support (101) moving said heads (1; 1A) by following a path along which the containers to be capped are conveyed, wherein cables (9) for the power supply and the reception and transmission of signals, data and commands terminating at the individual heads (1; 1A) connect in series, in pairs, heads (1; 1A) arranged in alternate positions on the support (101), the series of heads (1; 1A) being directly connected to a collector carried by the common support (101).

10. The capping machine (100) according to claim 9, wherein the cables (9) for the power supply and the reception and transmission of signals, data and commands connected to the individual heads (1; 1A) connect in series, in pairs, alternate heads (1; 1A) belonging to different head groups, each group of serially connected heads (1; 1A) being in turn directly connected to said collector independently of the other groups.

11. The capping head (1) according to claim 1, wherein the member (41) carrying the cam follower rollers (42) is associated with means (7, 43) for preventing, while the head (1) is advancing along the cam (104, 104a), unwanted rotary movements of the same head (1) possibly occurring during the translational motion.

12. The capping head (1; 1A) according to claim 1, wherein the shaft (2) has an axial cavity (20) accommodating means for driving cap-handling members carried by the same shaft (2).

13. The capping head (1; 1A) according to claim 5, wherein component-holding boxes (8; 8A) are mounted onto the stationary housings (6; 203) of the first electric motor (5) and, if provided, of the second electric motor (200), which boxes accommodate electronic components for supplying the motors (5; 200) with power and for controlling and monitoring the operations of the head (1; 1A), wherein cables (9) for the power supply and the reception and transmission of signals, data and commands from and to the components terminate at said boxes (8).

14. A capping machine (100) comprising at least one capping head (1; 1A) according to claim 13.

15. The capping machine (100) according to claim 14, comprising a plurality of capping heads (1; 1A) carried by a common support (101) moving said heads (1; 1A) by following a path along which the containers to be capped are conveyed, wherein the cables (9) for the power supply and the reception and transmission of signals, data and commands terminating at the individual heads (1; 1A) connect in series, in pairs, heads (1; 1A) arranged in alternate positions on the support (101), the series of heads (1; 1A) being directly connected to a collector carried by the common support (101).

16. The capping machine (100) according to claim 15, wherein the cables (9) for the power supply and the reception and transmission of signals, data and commands connected to the individual heads (1; 1A) connect in series, in pairs, alternate heads (1; 1A) belonging to different head groups, each group of serially connected heads (1; 1A) being in turn directly connected to said collector independently of the other groups.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other features and advantages of the invention will become more apparent from the following description of preferred embodiments made by way of non-limiting example with reference to the accompanying drawings, in which:

[0022] FIG. 1 is an isometric view of a capping turret equipped with capping heads according to the invention, in a first embodiment is which head translation is driven by a mechanical cam;

[0023] FIG. 2 is an enlarged axial cross-sectional and perspective view of a capping head according to the invention used in the turret shown in FIG. 1;

[0024] FIG. 3 is an enlarged axial cross-sectional and front view of a capping head according to the invention used in the turret shown in FIG. 1;

[0025] FIG. 4 is a perspective view of the bushing transmitting the rotary motion to the shaft;

[0026] FIG. 5 is an enlarged cross-sectional view of the head portion where the bushing shown in FIG. 4 is mounted; and

[0027] FIG. 6 is an enlarged axial cross-sectional view of a capping head according to the invention, in a second embodiment is which the translation is driven by an electric actuator.

DESCRIPTION OF EMBODIMENTS

[0028] Referring to FIG. 1, a rotating capping machine or turret 100 is schematically shown, which is equipped with a plurality of heads 1 according to a first embodiment of the invention for applying screw caps onto containers such as bottles, phials and so on.

[0029] Heads 1 are carried by a platform 1 integral with a shaft 102 with vertical axis, which is made to rotate about its axis in order to take the containers to be capped (not shown in the Figure), bring the containers and the heads to a capping position and subsequently bring the capped containers to a position of removal from capping machine 100. Heads 1 are mounted in respective seats 103 on platform 1 so that their axes are parallel to the axis of shaft 102 and their lower ends are associated with cap-holding cones 3 and hence with the members for picking/releasing the caps.

[0030] As known, during rotation of turret 100, heads 1 are submitted to an axial translational motion which brings them from a raised idle position (top dead centre) to a lowered screwing position (bottom dead centre) and vice-versa, and to a rotary motion about their axes in order to screw the cap onto the container.

[0031] The above structure is wholly conventional and hence it will not be described in more detail.

[0032] In the present exemplary embodiment, the vertical translational motion is obtained thanks to the cooperation of heads 1 with a mechanical cam 104 carried by a frame stationary relative to turret 100, more particularly the cooperation with a radial flange 104a of the cam. The top end of each head 1 has therefore means 4, described in more detail hereinafter, arranged to carry out such cooperation. Optionally, rods 7 parallel to the axes of heads 1 can be provided, which cooperate, during the translational motion, with means 4 in order to prevent unwanted movements of the heads possibly occurring while the heads are advancing along cam 104.

[0033] The rotary motion is instead imparted by a motor, more particularly a rotary electric motor, housed inside a housing 6 fastened to platform 101. The motor will be described in more detail below, with reference to FIGS. 2 and 3.

[0034] Housing 6 has fastened thereto guiding rod 7, and electronic components for power supply, control and monitoring of head 1 are also mounted on it. Such components are housed inside a component-holding box 8 at which cables 9 for power supply and reception and transmission of commands, signals and data terminate, such cables being received in suitable cable holders 10. Therefore, both boxes 8 and cables 9 terminating at them are not concerned by the translational and rotary movements of heads 1. In the drawing, the cables serially connect, in pairs, the components belonging to alternate heads 1, more particularly according to a daisy-chain arrangement. In other words, cables 9 connect together for instance first the heads in odd positions and the last odd head is connected to a first head in even position, which is in turn serially connected to the subsequent even heads. The first head in the chain is directly connected to a conventional rotary collector (not shown) carried by turret 100 and in turn connected in conventional manner to an external power source and to the control system of the capping machine.

[0035] The choice of the daisy chain arrangement is suggested by the fact that cables 9 employed are rather stiff and the connection of consecutive heads would cause excessively accentuated bending in the cables themselves.

[0036] It is to be appreciated that, in case of capping machines comprising a high number of heads 1, these could be divided into groups, for instance a first group comprising the heads in odd positions and a second group comprising the heads in even positions, and the cables serially connect, in pairs, alternate heads 1 in a same group. The different groups will then be connected to the rotary collector independently of one another.

[0037] The daisy-chain connection of the heads (or of the heads of the different groups) also enables dispensing with the multiple plug socket from which, in the conventional systems where the components are not mounted in stationary manner, the cables leading to the individual heads depart.

[0038] Referring now to FIGS. 2 to 5, a head 1 includes a rotating and translating shaft 2, the longitudinal axis of which is parallel to the axis of shaft 102 and which is equipped at its top end with the means 4 for guiding the movements of head 1 on cam 104 and along rod 7, and at its bottom end with the members for picking/releasing the caps (not shown). Shaft 2 is made as an integral piece and advantageously it has an axial cavity 9 intended for the passage of the means (not shown) actuating said members for picking/releasing the caps.

[0039] Motor 5 driving the rotation of shaft 2 comprises a stator 50 and a rotor 51, and stator 50 is fastened to the inner wall of housing 6 and is coaxially arranged around rotor 51. The latter is in turn arranged coaxially around shaft 2 and is decoupled therefrom as far as the translational motion is concerned so as to remain in a fixed axial position.

[0040] Shaft 2 is supported by two guiding bushings 11, 12, for instance recirculating ball bushings as shown in FIG. 4 for bushing 12, which are fastened to the end faces of housing 6 through suitable flanges 11a and 12a and seal the internal cavity of the housing, while however allowing axial sliding of shaft 2.

[0041] More particularly, shaft 2 is supported in freely rotatable manner by one of the bushings, in particular bushing 11 located at the top end of housing 6. The second bushing 12 is instead received within a cup-shaped bottom end portion 51a of rotor 51 and jointly rotates with the rotor. Rotor 51 thus extends substantially over the whole length of the internal cavity of housing 6, from the inner base of bushing 11 to flange 12a for fastening bushing 12 onto housing 6. Rolling bearings 13 between rotor 51 and the inner wall of housing 6 enable rotation of rotor 51 relative to the same housing.

[0042] Bushing 12 causes rotation of shaft 2 thanks to the cooperation between ribs 15 provided on the outer surface of shaft 2 and grooves 14 provided on the inner surface of bushing 12. Motion transmission can occur with the interposition of small balls (not shown).

[0043] Bushings 11, 12 are wholly conventional elements and a more detailed description thereof is not necessary for the understanding of the invention.

[0044] By such an arrangement of the components, motor 5 together with stationary housing 6 and the first and second bushings 11, 12 sealing the housing forms a self-standing module for driving rotation of shaft 2, independent of the manner in which translational motion of shaft 2 is driven.

[0045] As far as the latter motion is concerned, the means 4 cooperating with cam 104 and rod 7, if any, for generating and guiding such motion comprise a body 40 (hereinafter referred to also as decoupling joint), integral with the top end of shaft 2 and essentially consisting of a rolling bearing that is passed through by shaft 2 and that allows rotation thereof about its axis. Decoupling joint 40 has fastened thereto, in an easily detachable manner, an extension piece 41 vertically extending upwards, on which two cam follower rollers 42 with parallel horizontal axes, arranged to roll on the opposed faces of flange 104a, are mounted. Decoupling joint 40, or extension piece 41 supporting rollers 42, also has a cantilevered sleeve 43 in the cavity of which rod 7 slidably engages. Such an arrangement mainly aims at preventing rotation of body 40, and hence of shaft 2, when a change in the slope of flange 104a of cam 104 causes a torsion in shaft 2.

[0046] It is pointed out that, for the sake of simplicity of the drawing, components usually associated with the rotating and translating shaft of a capping head, such as the springs for applying the compression load, the angular position transducers (encoders) etc., are not shown in the Figure since they are not affected by the invention.

[0047] FIG. 6 shows a second embodiment of the invention, in which the translational motion of head 1A is obtained by means of a linear actuator, for instance a second electric motor 200, implementing a so-called virtual cam. The module driving rotation is identical to the one shown in the previous Figures and its components are denoted by the same reference numerals as used in such Figures. A piston 201 linearly slides inside that second motor 200 and it is made to translate jointly with decoupling joint 40 for instance by means of a rod 202 transmitting the linear motion. One end of that rod is fastened to the top end of piston 201, whereas the other end is fastened, in an easily detachable manner, to the outer race of the rolling bearing of decoupling joint 40. In this manner, during translation of piston 201, rod 202 drags shaft 2 with it. Reference numerals 203 and 204 denote the stationary housing and the heatsink, respectively, of motor 200. Housing 203 too is fastened to the stationary frame of turret 100 so that the components (i.e. rotor and stator) of the second motor 200 are decoupled form the movements of piston 201 and hence of shaft 2.

[0048] Moreover, similarly to what disclosed for motor 5, the electronic components for driving and monitoring motor 200 are housed inside a component-holding box 8A fastened to housing 203 of motor 200 and equipped with cable holders 10A at which the cables for power supply and reception and transmission of commands, signals and data terminate.

[0049] The invention actually solves the problems mentioned above.

[0050] Having a self-standing module for driving rotation of rotating and translating shaft 2, which module can be easily coupled either with piece 41 supporting the rollers or with rod 202 transmitting the linear motion, enables constructing machines where the drive for translational motion more convenient for the specific application is used, thereby dispensing, in particular, with use of a motor drive when this is not indispensable. Thus, a considerable power saving, the greater the higher the number of heads, can be achieved.

[0051] Besides the advantages related to power saving, a reduction in the number of parts to be kept in stock is achieved, in that a single module for driving rotation exists that can be directed to the production line either of machines with mechanical cams or of machines with linear motors. Moreover, if the needs of a client require so, a machine in which the module driving rotation is associated with a cam drive of the translation can be easily upgraded to a model with motor-driven translation by simply replacing roller-supporting piece 41 with transmitting rod 202 and linear actuator 200.

[0052] Additionally, having cables 9 terminating at boxes 8, 8A fastened onto housings 6, 203, which are elements mounted in stationary manner onto turret 100 and are not affected by the rotary and translational movements of head 1 they belong to, results in the same cables not hindering such movements and not running the risk of being damaged, without the need to provide a suitable movable wiring.

[0053] Moreover, shaft 2 made of a single piece and the motion transmission from bushing 12 to the shaft without need to employ particular shapes of the parts cooperating to this aim make constructing and assembling head 1 considerably simpler, thereby reducing the overall costs.

[0054] Lastly, no unit in the transmission chain of the rotary motion (and also no part of the linear actuator, when used in place of the cam) is translationally integral with shaft 2, so that the problems related to moving relatively heavy masses do not occur.

[0055] It is clear that the above description has been given only by way of non-limiting example and that changes and modifications are possible without departing from the scope of the invention as defined in the appended claims.