DE2559765C2 - Coupling for gripping and releasing sensitive workpieces, especially preforms made of plastic, in blow molding machines - Google Patents

Description

Raschen to be transported in sets known which attacks on the outside of the bottle necks. However the known gripping device is designed in such a way that the actuation of the in a sleeve-shaped sn Holder mounted gripping body when gripping a bottle through the neck bead of the bottle itself must be done in such a way that the whole Gripping device is lowered so far on the bottles set up, for example, in a crate that the gripping body during this lowering movement a position in front of the recesses in the guide sleeves take and under the action of the neck bulges of the bottles on the gripping body Side pressure slide into these recesses. As soon as the gripping body is in the recesses of the Guide sleeves are located, the bottle neck beads can go past the spherical gripping bodies and after this passage, the balls fall back into theirs under the action of gravity lower end position where the balls grip under the neck bead of the bottles. Even with the release operation use must be made of the side pressure exerted on the gripping bodies by the bottle neck beads are to press the gripping body into the recesses in the guide sleeve, so that the Bottle neck beads is given the opportunity to go down past the displaced gripping bodies. This known gripping device is therefore particularly suitable for use with compact glass bottles Beer bottles, limited which with a suitable one Neck bead for actuation of the gripping body are provided, and for use in the handling of sensitive preforms made of plastic are unusable in blow molding machines.

The present invention is therefore based on the object of developing the generic coupling so that that a particularly gentle treatment of sensitive workpieces, especially preforms made of plastic, when gripping and releasing is guaranteed by the coupling.

According to the present invention, this object is achieved in that the substantially cup-shaped formed support part axially movable within the corresponding cup-shaped bearing part is stored and has a number of openings in each of which one of the locks is walking, and that the layer part has a cam surface in the area of the inside of its lower side wall, which the detents radially inwards or outwards depending on the relative axial movement between the cup-shaped support part and the cup-shaped bearing part for gripping or releasing of the workpiece.

Due to the design of the coupling according to the invention, it is possible to control the relative axial movement between the support part and the bearing part in a radial movement by the locking devices, without that - in contrast to the gripping device according to DE-PS 9 63 677 - the workpiece to be gripped itself or parts thereof must be used as actuating elements for actuating the locking device.

Advantageous further developments of the invention emerge from the subclaims.

In the following an embodiment of the invention is explained in more detail with reference to the drawing. In the Drawing shows

F i g. Fig. 1 is a partially sectioned side view showing a conveyor in combination with a number of couplings according to the present invention shows, and

F i g. 2 and 3 side sectional views on an enlarged scale of a coupling on a bearing bracket and the release cam in a workpiece gripping or holding position or a workpiece release or loading position.

For the purpose of explanation, a preferred embodiment according to the invention will be

! 0, which is useful for conveying preforms 2 made of polyethylene terephthalate, which are shown in FIGS. 2 and 3 are partially illustrated and are fed from the loading device 8 (not shown) through an oven 9 using the conveyor 10 of FIG. 1, where they are heated to a predetermined state and after which the preforms are then released by means of appropriate devices for forwarding to a blow molding device 11 of any conventional type. Since the furnace and the blow molding equipment do not form part of the present invention, these two details are not explained in further detail. The workpiece 2 is held or gripped by a coupling 12 which, according to FIGS. 2 and 3, from the point in time when it is released by the loading device to the point in time when it is released by a release cam device 15 at the other end of the conveyor. The coupling is continuously rotated during the time it travels the conveyor line. The loading device is actuated in timed relation to the movement of the conveyor 10 and each individual coupling 12, whereby each preform is fed into the coupling while it is temporarily in the Loading position (reference symbol \ 2b) is stopped (compare FIG. 1). The coupling parts are in the open (release) position according to FIG. 3 held until the workpiece is inserted, whereupon the coupling is closed, ie is moved into the engagement or holding position according to FIG. After the workpiece or preform is thus loaded into clutch 126, the conveyor resumes its advance and each loaded clutch (e.g., 12c through \ 2d) is continuously rotated as it periodically moves through the furnace from position to position and moved to the point of release 12e which is on the right hand side of FIG. 1 is illustrated.

As shown in FIG. 1, the couplings are arranged in a pattern of parallel rows. In the

Embodiment thus illustrated are a number of clutches in rows of four clutches a bearing bracket 20 arranged, whereby these four clutches together through all operations are movable and deliver four preforms to the blow mold 11 at the same time. As shown in FIG. 1 are the Couplings similarly arranged in rows one behind the other, d. H. one behind the other so that the loaded couplings under the action of the driving force supplied by the conveyor from the loading station through the furnace to the release point. 12e (in the area of a slide to the blow molds 11, which without the usual perpendicular distance is illustrated due to the spatial limitation of the drawings) and the emptied couplings guided on the conveyor chain 66 then become the charging station moved back, this process being repeated over and over again.

The sponsor 10 provides a two-way Hienlirht = Finrirh.

tion represents the continuous rotation of each charged Induce coupling, while at the same time the intermittent advance of the couplings from the charging station to the unloading station of the machine is guaranteed

In the following, the structure of the coupling is explained with reference to FIGS. 2 and 3 explained in more detail.

F i g. Fig. 2 shows the position of the various individual parts of the coupling, whether a preform or another Workpiece is held or gripped by the coupling (or when the coupling is empty and ready for reloading is returned). F i g. 3 shows the relative positions of parts when the coupling releases a workpiece or record

The coupling 12 engages and releases the preform in response to the relative movement between them Individual parts, this movement converting an axial movement into a radial movement. The coupling consists of a first and a second cup-shaped part 25 and 26, respectively. The first cup-shaped part 25 is the outermost part and forms a bearing or support from which a hollow shaft 27 It has a closed end 28 from which a hollow shaft extends and also a tubular, preferably cylindrical wall 29. The wall of the first part also has a cam surface 30 on the inside of its lip or apron lying below, this cam surface in is divided into two parts, of which the lowest part is a release cam surface 31 and the overhead portion of a holding or workpiece gripping cam surface 32 is a step 33 or any useful inclined surface connects these two cam surfaces. The wall 31, 32 can simultaneously serve as a heat shield to keep the injection molded neck and screw threads from heating 16,17,18 to prevent the preform, so that the mold produced by injection molding under minimal Deformation due to the problems created by thermal storage is preserved.

A number of detents 35, which are preferably formed by spherical bodies, such as, for example, ball bearings, are carried by the second cup-shaped part or carrier 26. The detents are the components that physically engage the preform. In the preferred embodiment, the inclined surface on the underside of the sealing or retaining ring 17 provided on the preform is such that radial inward movement of the detent wedges the detent below that surface _: around the top or lip of the preform firmly against seat 36 the preform, which is held in the upper end of the carrier by the seat flange 37 which is in engagement with a retaining ring 38 which is received in a groove 39

The second coupling part 26 is designed as a carrier part and is held axially movably in the bearing part 25 and has an end wall 41 and a tubular wall 42 to the detents 35 as a support for effective to hold them so that the detents can move radially when the carrier 26 axially around Stretching enough to make the locks move 35 from the holding cam surface 32 according to FIG. 4th on the release cam surface 31 according to FIG. 5 and vice versa to move.

The carrier 26 of the detents has a closed one End 41, from which a cam follower 44 protrudes upwards and from which the tubular one protrudes downwards.

preferably cylindrical wall 42 proceeds, which has a number of openings 45, which completely are carried out through the wall. Preferably three openings are provided, whereby three locks 35 can be used. The openings 45 are shaped as conical bores that face outwards are designed to diverge from the middle part of the housing. The balls forming the detents 35 are consequently tapered in this

ίο holes kept, however, this can go far enough protrude to, as shown in FIG. 4 illustrates gripping the workpiece firmly.

The cam follower 44 connected to the carrier is slidably mounted in the hollow shaft 27 and engages therethrough and extends beyond the shaft a distance sufficient to engage with an actuating device, such as various cams (compare the release cams 15) to get into engagement, as shown in FIG. 2 is illustrated

A resilient spring device 47 is formed by a helical spring serving as a retaining spring, which between the shaft 27 forming the bearing and the cam follower part 44 of the housing under compressive prestress arranged and held on this by a retaining ring and a disc 48 and 49 and the Biases the lock carrier in the bearing part, d. H. the parts in the in F i g. 2 illustrated relative positions pretensioned

A second resilient spring device is a seat spring 50 between the closed end 41 of the locking carrier and the workpiece seat 36 is provided. The seat spring is under pressure and pushes the carrier and the seat away from each other.

A pinion or gear 51 is also attached to the upper end of the hollow bearing shaft 27 in order to continuously rotate the coupling about an axis extending through the coupling when the latter is moved with the conveyor. The bearing shaft 27 is rotatably supported on the bearing bracket 20 in a pair of slide bearings 52 which are preferably formed by permanently lubricated bearings of the insert-like bush type, which are readily available on the market.
Each clutch 12 operates in the following way:

The workpiece 2 is first inserted or by pressing down the cam follower part 44 released, which compresses the spring 47 and the carrier 26 axially downward in the direction the in F i g. 5, whereupon the position shown by the seat 36 and the spring 50 formed, the ejection supporting means become effective, so that the seat spring 50 the seat 36 pushes down to a position where the retaining ring 38 stops further movement of the seat Due to these movements, the detents 35 are radially in their openings 45 against the Release cam surface 31 moves, thereby releasing the workpiece. Reach the items at this point in time the in F i g. 5 illustrated positions and if a workpiece is in the coupling is at the beginning, it is released, but if the clutch is empty, it is charged, by inserting a workpiece 2 and moving it axially until the detents 35 grip it, with finally the one shown in FIG. 2 illustrated position is assumed. How it works when you hold takes place essentially in reverse order

follow the steps described first and the locking mechanisms 35 come fully into engagement with the ascent to the retaining cam surface 32 Preform. As a result, there is relative axial movement between the two cup-shaped parts 25, 26 converted into a radial movement of the detents 35.

For this purpose 2 sheets of drawings ι ο

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Claims (7)

Patent claims: 1. Clutch for releasing and grasping delicate Workpieces, in particular preforms made of plastic in blow molding machines, which are movable by means of conveyors between the workstations, the coupling for Receiving a workpiece, a bearing part and a support part which is axially displaceable relative to this in having a concentric arrangement and a number! of by the relative movement between Camped ;! and carrier! actuatable locks is provided, which convert the axial relative movement into a radial movement to the workpiece to release or to grasp, characterized in that that the substantially cup-shaped carrier part (26) is axially movable within of the corresponding cup-shaped bearing part (25) is mounted and a number of openings (45), in each of which one of the detents (35) is mounted, and that the bearing part (25) in the Area of the inside of its lower side wall (29) has a cam surface (30) which the locks (35) radially inwards or outwards depending on the relative axial movement between the cup-shaped carrier part (26) and the cup-shaped bearing part (25) for gripping or forcing the workpiece (2) to be released. 2. Coupling according to claim 1, characterized in that the detents (35) as expandable and contractible devices are formed. 3. Coupling according to claim 1, characterized in that the cam surface (30) has an axially below lying workpiece release section (31) and an axially further above and radially having inwardly projecting workpiece gripping portion (32), wherein by an Axialbcwegung the Carrier part (26) with respect to the bearing part (25) the detents (35) radially outward to release a workpiece (2) or can be moved radially inward for gripping a workpiece (2). 4. Coupling according to claim I or 3, characterized in that that the catches (35) are formed by spherical bodies, the openings (45) are formed in the carrier part (26) as conical bores (45) which diverge outwards, and wherein the spherical bodies (35) are dimensioned such that they are too large to pass through the to get through the smallest diameter of the bore (45). 5. Coupling according to one of the preceding claims, characterized in that in the carrier part (26) at the end remote from its lower edge a workpiece seat (36) that can move to a limited extent is provided. 6. Coupling according to claim S, characterized in that the workpiece seat (36) in the direction of The lower edge of the support part (26) is spring-biased by a spring (50). 7. Coupling according to one of the preceding claims, characterized in that the carrier part (26) has a cam follower part (44) at its end opposite the open end and that the carrier part (26) is held pretensioned in the bearing part (25) by a spring (47). The invention relates to a coupling for gripping and releasing sensitive workpieces, in particular Preforms made of plastic in a blow molding machine, which by means of conveyors between the workstations are movable, the coupling for receiving a workpiece, a bearing part and has a carrier part axially displaceable relative to this in a concentric arrangement and wherein a number provided by locks that can be actuated by the relative movement between the bearing part ίο and the carrier part that convert the axial relative movement into a radial movement in order to release or close the workpiece to grab. The invention is related to this application for the purpose of illustration without limitation described with devices for handling workpieces, the preforms made of injection molded Have plastic, which are reheated to a carefully controlled temperature, immediately before moving to a bottle with a screw-threaded neck for closure by means of a Screw cap are blow molded. The preform has a circular cross-section and is in engagement Parts of the coupling that come with the preform likewise have a circular cross-section. Blow molding has an increasingly important position in the field of the production of hollow bodies, such as containers or the like made of a wide variety of plastics and synthetic resins, such as Polyethylene, polyvinyl chloride, polyacrylic and nitrile, polyethylene terephthalate and the like. Taken. The technical field of blow molding has changed with reference to the way the work material is made entered into the mold in which it is blow molded develops in two main directions, viz Extrusion blow molding and injection blow molding. As indicated above, the present invention with reference to injection blow molding. In the blow molding process, the preforms are conveyed through an oven, where they are more uniform Way to be heated. This is achieved in that the preform is gripped by the coupling, and then by means of the conveyor on which the coupling gela-4ΐ is gelci'et through the furnace while the preform is continuously rotated to make it uniform to warm up. The preform is then moved out of the furnace and from the coupling and The preform is then released into a blow molding system where it is placed in a container is reshaped. From DE-AS 11 02 639 a rod-like bottle gripper for bottle nipping and unpacking machines is known, which is designed as an inner gripper that can be inserted into the necks of the bottles. In this case, actuation devices are provided that allow the targeted gripping and releasing of the conveyed material. The above-mentioned internal gripper has the disadvantage that it can only be used with a bottle neck that tapers upwards, which, however, is usually cylindrical, especially in the case of plastic preforms. Moreover, due to the usually only slight inclination of the bottle neck wall to the bottle axis, relatively high radially acting clamping forces occur in such an internal gripper, which cause damage to the neck, particularly in the case of sensitive workpieces such as preforms.
From DE-PS 9 63 677 is a Greifvorrichtune for