Description

Field of the art

The present invention operates in the field of components for thermoplastic molds. Still more in detail, the component to which the present invention makes reference is termed, in technical jargon, “saber-like element” and consists of a mechanism for the extraction of the part from the mold, possibly in undercut, at the end of the molding.

Prior art

Presently, by means of the industrial process of injection molding of plastic polymers, increasing numbers of complex plastic components are produced.

Many also have shapes with comers in undercut. The extraction of such objects from the mold, once opened, must be executed by means of extractors which lift the plastic component, by now solidified. Several types of extractors for releasing the undercuts are in jargon termed “saber-like elements”, and various types thereof are present on the market.

For a correct operation of the saber-like element, it is essential that this be precisely adjusted, i.e. it is lifted and retracted by the exact size in order to not project from the mold, when closed. It is also important that the saber-like element not be overheated in a manner different from the mold, since its contact with the molded component could create surface defects. Depending on the requirements, therefore, saber-like elements of height-adjustable type that are cooled by a dedicated circuit are already present on the market; nevertheless, the Applicant has identified several critical issues that are common to the lifting systems presently on the market, which the present invention intends to resolve.

Such critical issues can be summarized in the following main points:

1) System for adjusting the height of the rod of the saber-like element The systems presently on the market, for the adjustment of the height of the rod, are provided with mechanisms with a stop abutment on the clamping between the nut and mechanical locknut. It follows that such mechanism could be moved during the working cycle or during a disassembly for maintenance. The saber-like elements not provided with an adjustment system require adjusting, a rather complex process, with consequent losses of time and productivity during the construction process of a mold. ) Cooling system

The cooling circuit is constrained to the rod-carrier carriage and any modification of the saber-like element, in several embodiments linked to the prior art, involve the need for disassembling the entire cooling circuit and hence, during remounting, newly assembling it.

In addition, the presence of a circuit for the water could involve oxidation, which could contribute to wedging the coupling of the saber-like element in the relative rod-carrier carriage, blocking it. A further critical issue belonging to the prior art is the mounting and the disassembly of the cooled saber-like element which often causes damage to the gaskets, rubbing and friction which ruin the components. Still today, in many saber-like elements being used, blocking phenomena between the rod and the rod-carrier persist, which require drastic maneuvers for the saber-like element, in order to eliminate this rubbing and release the object, but which involve the possibility of seizure/galling.

With regard to the disassembly, there is once again the problem of the disassembly of the cooling circuit, when present. ) Bulk

Presently, the system of connection between the rod and the rod-carrier requires considerable bulk in the mold volume. Sometimes it is necessary to have at least two saber like lifting elements that are very close, but due to the volume of the entire system it is very difficult to mount two saber-like elements in a limited area. ) Geometry of the rod Presently, rods on the market are all cylindrical. If it was necessary to have a different geometry, molding professionals are used to making on their own the rod with prismatic section that they require. In particular the rods with prismatic section are necessary for small sliding sizes. The autonomous production of the necessary saber-like element is clearly not an optimal solution, both regarding the costs and the production times, and regarding the non-simple adaptability of saber-like elements produced as a “single piece” to the connection mechanisms of the standard components.

Description of the invention According to the present invention, a cooled saber-like lifting element for thermoplastic molds is attained that effectively solves the abovementioned problems.

The saber-like element of the present invention, like the others that can be found on the market, is constituted by a rod whose lower end is adapted to be partially inserted in a rod-carrier carriage device, while the upper end is engaged with an insert. In the preferred embodiment, the insert is interchangeable with others of different shape by means of a common mechanical system since it is directly correlated with the geometry to be molded.

The rod-carrier carriage device is laterally connected to a pair of sliding plates and on the lower part to a fixing screw.

In the preferred but non-binding embodiment of the present invention, unlike the sliding plates of the prior art, which establish a sliding friction with the rod-carrier, those of the present invention are advantageously configured with a hinge-like constraint adapted to allow 2 degrees of freedom to said rod-carrier device, generating a rolling friction and hence protecting the mechanism from possible blocking.

The rod, which can have circular or prismatic section, is adapted to be reversibly inserted within the suitable recess of the rod-carrier carriage.

More in detail the rod has an upper portion, an intermediate portion, a lower portion and a final threaded portion, which have diameters (or they are inscribable in diameters) that are decreasing. The intermediate portion is delimited on the upper part by a seat for sealing gaskets. The lower portion includes a further seat for a sealing gasket.

Advantageously, said seats have a rounded section adapted to prevent the formation of cracks. At the threaded final portion of the rod, an adjustment nut is advantageously engaged in an adjustable manner; such adjustment nut is adapted to be engaged with an abutment profile of the recess of the rod-carrier, stopping the descent of the rod and adjusting the closure of the saber-like element insert with the relative coupling seat.

The recess of the rod-carrier carriage is thus configured in four sections, corresponding to the four sections of the rod, with sections with diameter (or inscribable in a diameter) that are decreasing from top to bottom. In particular it comprises:

• an upper portion adapted to be engaged with said upper portion of the rod, maintaining a certain movement tolerance. In particular, when said rod is inserted in the rod-carrier, a first contact area with carriage-like constraint is generated in the upper portion;

• an intermediate portion adapted to be engaged with said intermediate portion of the rod. When the rod is inserted within the rod-carrier, a second contact area with carriage-like constraint is generated in the intermediate portion;

• a lower portion adapted to house the lower portion of the rod with a certain movement tolerance. This portion is provided on the lower part, at the edge of coupling with the lower portion, with an abutment profile which is engaged with said adjustment nut, stopping the insertion of the rod in the rod-carrier;

• a final portion adapted to house the threaded final portion of the rod with a certain movement tolerance, and adapted to be engaged with the fixing screw (if present).

It is important to specify that, between the diameter of the intermediate portion of the rod and the diameter of the intermediate portion of the rod-carrier, an air space (tolerance) is present that is adapted to allow the vertical sliding of the rod, preventing the contact and the wear of said gaskets. More in detail, the two gaskets are situated between the first and second contact area, protecting them from wear. Advantageously, at the rod-carrier device, a cooling circuit is also present that is adapted to carry coolant water within the recess, cooling the rod and the insert. When the saber-like element is mounted, the cooling circuit has the outlet nozzles for the water at the upper portion of the recess and hence at the intermediate portion of the rod. Advantageously, all the components of the saber-like element described up to now are made, in the preferred version, of stainless steel. In particular, the rod-carrier rod will have a coating adapted to reduce the friction between the components in contact.

In addition, in the preferred variant of the invention, said rod is provided with external grooves adapted to be filled with any one substance adapted to facilitate the sliding, such as for example grease.

Among the main advantages of the invention, in each of its possible embodiments, it must be underlined that the entire mechanism of the saber-like element is extractable from the mold and adjustable (by adjusting or substituting the adjustment nut) even with the mold mounted. Hence there is no need for long disassembly times for the adjustment and the maintenance of the saber-like element.

More in detail, analyzing the critical points encountered in the prior art, the advantageous solutions and improvements that the saber-like element of the present invention brings are listed hereinbelow:

1) System for adjusting the height of the rod of the saber-like element The extraction of the rod from the rod-carrier device of the saber-like element, in order to adjust the height thereof, is extremely easy and quick. It does not require the disassembly of the entire saber-like element and due to the expedients that prevent errors of remounting, the return in operation of the saber-like element with the height adjusted is very easy for any operator, even those who are not experts. The stop abutment of the rod in the rod-carrier, in fact, is a mechanical stop of the adjustment nut against a suitable abutment arranged in the recess of the rod-carrier device. In order to fasten all of the above, it will suffice to clamp the lower screw of the rod-carrier device. 2) Cooling system

The cooling system, when present, has been designed to be fixed within the mold and thus it does not require being disassembled together with the rod. This involves numerous advantages in terms of time and of wear of the cooling circuit. 3) Bulk

Among the main advantages of the present invention, there is the reproducibility thereof in systems also with very small diameters, with bulk clearly smaller than the known saber like elements. This allows particularly advantageous embodiments, constituted for example also by two or more saber-like lifting elements in a very limited area of the same mold. 4) Geometry of the rod

The system described hereinbelow, object of the protective scope offered by the present patent, has the advantage of being reproducible for any geometric form of the rod.

As previously indicated, in fact, only saber-like elements with cylindrical section can be found on the market, while the particular technical expedients that will be described hereinbelow in order to define the invention are applicable to saber-like elements with section of any geometry. In addition, presently simplified prismatic saber-like elements, like that which is the object of the present invention, do not exist: indeed, this is a rod with an attachment adjustable to standard components of the saber-like element.

In fact, a system is provided for the immediate centering between the insert and the rod, adaptable to all the sizes and shapes of the saber-like element, particularly useful in the case of saber-like elements with prismatic section.

In addition, advantageously, a rod with prismatic section can be inserted in a rod-carrier having recess with cylindrical shape, giving rise to a saber-like element with mixed shape: half cylindrical and half prismatic, maintaining unchanged the advantages that the invention involves.

Advantageously the present invention involves further additional improvements with respect to those encountered in the prior art, which are the following:

5) System for moving the rod-carrier carriage A further very important advantage that the invention brings is the possibility to integrate a system with rolling friction rather than sliding friction.

The sliding mechanism of the rod can be defined “anti-seizure/anti-galling” since it slides on a cylindrical bushing that generates a rolling friction constraint. Such type of constraint, with respect to that of sliding friction, allows 1 degree of freedom more, which allows obtaining a more flexible system that gives the necessary movement tolerance, in case of start of seizure/galling, in order to release the mechanism.

6) Gasket protection system

Also the expedients of the cooling circuit are adapted to protect the sealing gaskets from wear during the step of mounting and disassembly of the rod. Due to a combination of tolerances, they are always protected from possible contacts with walls that are not those of their direct seat, hence preventing possible rubbing and breakage on the gaskets. In addition, all the edges that the gaskets encounter along the mounting/disassembly path are suitably rounded.

7) Anti-crack system

The rod-carrier device is in fact suitably sized in order to prevent the onset of cracks from the grooves present on the rod and the grooves present on the rod are all suitably beveled.

8) Possibility of errors in mounting

Due to the geometrical details that characterize the rod and the rod-carrier, it is impossible for the operator charged with the disassembly and subsequent remounting of the rod and of the rod-carrier to err regarding the insertion direction.

9) Flexibility of use

Advantageously, the system of the present invention is adaptable for use with the products that that can already be found on the market. Such advantageous characteristic is reflected in particular on the rods with prismatic section which, up to now, have never been made modular, like that of the present invention.

Moreover, it is always compatible with all the standard components that can already be found on the market, due to the particular specially-designed mechanical attachments. Also the materials for making the components of the saber-like element of the present invention have been designed and improved with respect to the prior art. In order to prevent aggressions by limescale and rust, the ideal material is quenched stainless steel. With this, the rod-carrier device is advantageously attained. Nevertheless, the quench hardening process renders the steel excessively rigid and hence subjected to breakage of fragile nature. For such reason, the rod might not be made of the same material. A “coating” has thus been designed that is specific for the rod of the saber-like element. This consists of a coating of the rod which confers characteristics thereto that reduce the friction, anti-rust and anti-limescale characteristics, particularly useful in the case of presence of a cooling system. The advantages offered by the present invention are evident in light of the description set forth above and will be even clearer due to the enclosed figures and to the relative detailed description.

Description of the figures The invention will be described hereinbelow in at least a preferred embodiment, as a non limiting example with the aid of the enclosed figures, in which:

- FIGURE 1 shows a three-dimensional view of a saber-like element 100 according to the present invention.

- FIGURE 2 illustrates an axonometric exploded view of the saber-like element 100 of the preceding figure.

- FIGURE 3 shows more in detail the components of rod 10 and rod-carrier 30.

- FIGURE 4 depicts the size ratios between the various components of the portion of rod 10 to be inserted in the rod-carrier 30.

- FIGURE 5 shows in three steps (Fig. 5(a); Fig. 5(b); Fig. 5(c)) the insertion of the rod 10 in the relative rod-carrier device 30.

- FIGURE 6 shows the prismatic version of the rod 10 of the present invention.

- FIGURE 7 shows the reversible connection between the insert 20 and the rod 10 in its prismatic version. - FIGURE 8 once again shows the rod 10 - rod-carrier device 30 - cooling system 31 assembly, in the assembled configuration. From the transparent elements, the particular accuracy of the diameters is inferred such that the objects of the present invention are achieved. - FIGURE 9 shows the rounded parts 70 specially created for preventing errors during the mounting of the rod-carrier and the anti -unscrewing channels 71 suitably made for further ensuring the clamping of the rod with its screw.

- FIGURE 10 illustrates the locking pin 90 included in one of the variants of the present invention, in particular used for exit angles of the rod with respect to the mold opening axis that are greater than 20°.

- FIGURE 11 represents more in detail the reversible mechanism of centering and connection between a rod 10, in this case prismatic, and an insert 20 of any shape.

Detailed description of the invention The present invention will now be illustrated as a merely non-limiting or non-binding example, with reference to the figures which illustrate several embodiments relative to the present inventive concept.

With reference to FIG. 2, all the components of a cylindrical saber-like element 100 are shown according to the preferred embodiment of the present invention. At the top, the insert 20 is indicated which can have any shape and is interchangeable with others provided with the same mechanical system of connection to the upper end of the rod 10, whatever this is.

Meanwhile, the lower end is constituted by an upper portion 14 having the largest diameter Dl, below this an intermediate portion 14’ has a smaller diameter D2; below the latter, a lower portion 14”, just above the position of the locking nut 11, has a diameter D3 that is even smaller. The rod 10 also comprises a threaded final portion 14’” with a final diameter D4 smaller than all the other diameters.

Between the upper portion 14 and the intermediate portion 14’, a first seat 12’ is present for a gasket such as, for example, an O-ring 13. Likewise, at the lower portion 14”, a second seat 12” is arranged for a second O-ring 13.

In order to prevent the formation of cracks, the section of the seats 12’-12” is rounded, i.e. completely lacking sharp corners.

The threaded final portion 14’” of the rod 10 is engaged with an adjustment nut 11 which, when inserted in the recess 32 of the rod-carrier device 30, encounters an abutment profile 37. The adjustment of the height of the nut 11 on the rod 10 will thus determine the projection of the rod 10 and of the relative insert 20.

Also the recess 32 of the rod-carrier device 30 is configured in four sections corresponding to the four portions of the rod 10 plus an upper rounded part and two intermediate parts that act as a slide during the coupling.

An upper portion 33 has the largest diameter II. Below this, an intermediate portion 33’ has a smaller diameter 12 and, below this, a lower portion 33” has an even smaller diameter 13. The final portion 33’” of the rod-carrier 30 finally has a fourth diameter 14 that is smaller than all the others, adapted to house the final portion 14’” of the rod 10.

The size ratios between the diameters of the rod and the diameters of the rod-carrier have been designed to allow the vertical sliding of the rod 10, preventing the contact and the wear of said gaskets 13.

In particular, defining A as the coupling tolerance between the diameters of the rod, the diameters of the rod-carrier device and all the diameters that are encountered during the mounting and the disassembly of the rod 10 in the rod-carrier 30 and from the mold, and defining B as the tolerance between gaskets 13 and all the diameters that are encountered during the mounting and the disassembly of the rod 10 in the rod-carrier 30 and from the mold, are such that A is always smaller than B.

In addition, the contact area 35 between the rod-carrier 30 and the rod 10 is suitably adjusted with respect to the diameter and height in a manner such to prevent the formation of cracks due to the bending of the rod during the working thereof.

Such constraint allows the vertical sliding of rod 10 and rod-carrier 30 but prevents the bending of the portion of rod 10 that is situated between the two contact areas 35-36, thus preventing tensions in the portion affected by the two gaskets 13.

For the cooling of the system, the rod-carrier device 30, in its preferred embodiment, also comprises a cooling circuit 31 provided with outlet nozzles for water at said upper portion 33 of the recess 32.

A final, but not less important expedient, regards the sliding plates 40 which are engaged laterally to said rod-carrier device 30. These are configured, in the preferred embodiment, with a hinge-like constraint 41 adapted to allow 2 degrees of freedom, generating a rolling friction and hence protecting the mechanism from an early wear which would be due to a sliding friction.

Finally, it is clear that modifications, additions or variations that are obvious for a man skilled in the art can be made to the invention described above, without departing from the protective scope provided by the enclosed claims.