TECHNICAL FIELD Non-Limiting embodiments disclosed herein generally relate to a toggle mechanism, and more particularly to a device for extending a service life of a toggle joint therein.

BACKGROUND OF THE INVENTION A typical injection molding system includes, amongst other things, a clamp unit that is operable to provide the motion needed for closing, clamping, and opening of an injection mold arranged therein. A common variety of clamp unit is a so-called 'toggle clamp'. With reference to FIG. 1 there is depicted a typical toggle clamp 10. The toggle clamp 10 is characterized by a toggle mechanism 12 that is arranged between a clamp platen 14 and a moving platen 16 and wherein a hydraulic cylinder or some other mechanical force device 16 is connected to the toggle mechanism 12 to exert an opening force during opening of the injection mold 30, a closing force during closing of the injection mold 30 and a holding force during injection of molding material into the injection mold 30. A clamping force to hold the injection mold 30 closed during injection is provided by the mechanical advantage of the toggle mechanism 12. The toggle mechanism 12 itself includes multiple toggle joints 18 consisting of lever arms 20, 22 forming an angle with each other and pivoted about a pivot pin 24A. The free end of the lever arms 20, 22 are pivoted on fixed pivot pins 24B, 24C. Any movement to bring the levers nearly into line causes a very large pressure to be exerted at the ends. A more detailed description of the construction and the operation of typical toggle clamps may be referenced in the "Injection Molding Handbook" ISBN 0-442-27815-2. Furthermore, other examples of toggle clamps may be referenced in any one of the following patents:

US patent 4,773,845 to Nagura et al., published on September 27, 1988 discloses a toggle-type mold-clamping apparatus including at least a pair of swingable arms and toggle pins for connecting the arms in a swingable manner through toggle bushings each of which is constructed of a cylinder element and pellets embedded in a peripheral surface of the cylinder element at intervals of a certain distance so as to be exposed to an inner peripheral surface of the cylinder element, while a lubricant film of a grease mixed with fine particles of solid lubricant is applied to sliding surfaces of the toggle pins and the toggle bushings, resulting in excellent lubrication being realized in the apparatus. US patent 5,059,365 to Hertzer et al., published on October 22, 1991 discloses a method and apparatus for automatically setting the die height platen on a toggle-operated injection molding machine to achieve a desired mold clamping force. A control is provided and contains information relating a desired clamp tonnage with a toggle crosshead displacement, in order to permit setting the die height platen for a particular set of molds so that the clamp, when operated, will automatically provide the desired clamping force between the mold members. The adjustment is provided by moving the die height platen in response to deviations from a predetermined set of conditions, the die height platen being moved by an hydraulic motor and chain drive to shift the die height platen along guide rods that extend between the die height platen and a stationary mold platen.

US patent 5,622,737 to Hehl, K., published on April 22, 1997 discloses a mold closing unit for use in an injection molding machine for processing plastifiable materials, including a first device for transferring a movable mold carrier, and a second device for generating the closing force. The first device is supported at a first supporting element. The second device acts on the first device, the first supporting element and the movable mold carrier. The second device for generating the closing force is an eccentric drive or a hydraulic drive units which enables a process for force control.

US patents 6,796,783 and 7,004,746 to Weinmann, R. et al., published on September 28, 2004 and February 28, 2006, respectively, each disclose a closing part comprising an electromechanical drive for a CD injection molding machine having a working stroke and a servicing stroke. The entire mold closing unit is characterized by the combination of a short-stroke crank mechanism which is operated by an electric motor and which is provided for the working stroke and of a central electromotive column-type nut drive for the servicing stroke. According to the invention, synchronous motors or asynchronous motors are used with corresponding servo boosters to realize servo axles. The central column drive is used as a control element of the closing force control, together with a force sensor for detecting the closing force, as an actual value transmitter and as a control device. US patent RE33248 to Schad, R., published on July 3, 1990 discloses a clamp mechanism for selectively locking and unlocking a first member in a first position relative to a second member comprises a linkage system connecting the first and second members and drive means for articulating the linkage system for moving the first member relative to the second member. A fluid link is provided for locking the first member in position relative to the second member wherein the fluid link is actuated upon sensing the first member approaching the first position. With such toggle mechanisms it is commonplace to lubricate the toggle joints where they are pivoted about the pivot pins. Typically grease and/or oil are used to lubricate the toggle joints. Both manual and automatic means are known to apply the lubricant. Once the lubricant is applied at the pivot pin it is then distributed with cyclic movement of toggle joint.

An example of a toggle joint lubrication system may be referenced in US Patent 7,351,049 to Wang, J., published on September 8, 2006. In particular, the patent discloses a toggle mechanism of an injection molding machine consists of upper and lower toggle assemblies, which are pivoted to a fixed tail support at a first end, and a movable mold support of an injection molding machine at a second end; each of the toggle assemblies has two toggles pivoted together, each of which has pivotal holes on two ends; pivotal rods are passed through corresponding pivotal holes of the toggles to pivot the toggles together; pivotal rods are used to pivot the toggle assemblies to the fixed tail support and the movable mold support; each pivotal rod has oil holes in radial and axial directions; the oil holes communicate with the pivotal holes of the toggles, and each toggle has an internal oil passage communicating with its pivotal holes; lubricating oil will circulate in the toggle mechanism after conduits and filtering barrels are connected to the pivotal rods.

As previously mentioned, the distribution of the lubricant at the pivot pin depends to some extent on the movement of the toggle joint. As such, limited movement of the toggle joint that leads to ineffective lubrication thereof, such as with the operation of injection molds having very short mold strokes, will lead to premature wear of the toggle joint. Providing some means of extending the serviceable life of the toggle joint would have clear economic benefit.

SUMMARY OF THE INVENTION

A general aspect disclosed herein is to provide a device for extending a service life of a toggle joint of a toggle clamp. The device includes a pin rotator that is connected to a first pivot pin of the toggle joint, the pin rotator being configured to selectively rotate the first pivot pin within a first seat of a first lever arm of the toggle joint.

Another general aspect disclosed herein is to provide a controller including instructions being embodied in a controller-usable memory of the controller, the instructions for directing the controller to execute a method of operating a device to extend a service life of a toggle joint of a toggle clamp. The method comprises directing a pin rotator that is connected to a first pivot pin of the toggle joint to selectively rotate the first pivot pin within a first seat of a first lever arm of the toggle joint. These and other aspects and features of non-limiting embodiments will now become apparent to those skilled in the art upon review of the following description of specific non-limiting embodiments of the invention in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

The non-limiting embodiments will be more fully appreciated by reference to the accompanying drawings, in which:

FIG. 1 depicts a side view of a toggle clamp in accordance with the prior art.

FIG. 2 depicts a section view through a toggle joint that includes a device in accordance with a non- limiting embodiment of the present invention.

FIG. 3 depicts a side view of a toggle clamp that includes the toggle joint and device of FIG. 2.

FIG. 4 depicts a flow chart of a method in accordance with a non-limiting embodiment of the present invention.

The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted.

DETAILED DESCRIPTION OF THE EMBODIMENT(S

Reference will now be made in detail to various non-limiting embodiment(s) of a device and a related method for extending a service life of a toggle joint. It should be understood that other non- limiting embodiment(s), modifications and equivalents will be evident to one of ordinary skill in the art in view of the non-limiting embodiment(s) disclosed herein and that these variants should be considered to be within scope of the appended claims.

Furthermore, it will be recognized by one of ordinary skill in the art that certain structural and operational details of the non-limiting embodiment(s) discussed hereafter may be modified or omitted (i.e. non-essential) altogether. In other instances, well known methods, procedures, and components have not been described in detail.

With reference to FIG. 2 there is depicted a toggle joint 118 of a toggle mechanism 112 (FIG. 3) for use in a toggle clamp 100 (FIG. 3) of an injection molding system (not shown). The toggle joint 118 is configured to provide a connection between a first lever arm 120 and a second lever arm 122 of the toggle mechanism 112.

The toggle joint 118 is of a typical construction in the art insofar as the basic structure of the first lever arm 120, the second lever arm 122 and of a first pivot pin 124A that links ends of the two together. More particularly, the end of the first lever arm 120 is arranged between a first prong 123 A and a second prong 123B of the second lever arm 122 with the first pivot pin 124A passing therethrough. Within the end of the first lever arm 120 there is provided a first seat 127 A for receiving the first pivot pin 124A. Likewise, the first prong 123 A and the second prong 123B also provide a pair of seats for the first pivot pin 124A, namely a second seat 127B and a third seat 127C, respectively.

Whereas the first seat 127 A is typical in that it rotatably receives first pivot pin 124A, the toggle joint 118 is different than typical in that the second seat 127B and the third seat 127C are also configured to rotatably receive the first pivot pin 124A. That is, the first pivot pin 124A is not normally rotatable, in use, relative to both the first lever arm 120 and the second lever arm 122.

To provide a low friction bearing within which the first pivot pin 124A is rotatable, the first seat 127A, the second seat 127B and the third seat 127C may each be defined within a bearing bushing or other variety of bearing. More particularly, the first seat 127 A is defined in a first bearing bushing 126A that is associated with the first lever arm 120, whereas the second seat 127B and the third seat 127C are defined in a second bearing bushing 126B and a third bearing bushing 126C, respectively, that are associated with the first prong 123 A and the second prong 123B of the second lever arm 122.

The toggle joint 118 is also different than typical in that it includes a device 140 in accordance with a non-limiting embodiment of the present invention that is configured for extending a service life thereof. What is meant by service life is the expected duration (e.g. number of molding cycles) during which the toggle joint 118 can be expected to function adequately for its intended purpose. More particularly, the device 140 includes a pin rotator 142 that is connected to the first pivot pin 124A of the toggle joint 118. The pin rotator 142 is configured to selectively rotate the first pivot pin 124A within the first seat 127 A of the first lever arm 120 and within the second seat 127B and the third seat 127C of the second lever arm 122. In more specific terms, the pin rotator 142 is a motor, wherein a stator 143 of the motor is connected to the second lever arm 122 and the rotor 144 of the motor is directly coupled to an extension portion 125 of the first pivot pin 124A. The construction of the motor is not particularly limited, and may include, for example, a direct drive motor. The manner in which the pin rotator 142 is connected to the first pivot pin 124A (i.e. direct or indirect) is not particularly limited.

The intent in rotating the first pivot pin 124A within the first seat 127 A is two-fold. Firstly, it may be possible to distribute unavoidable operationally induced wear over a larger portion of an outer surface 125 of the first pivot pin 124A and thereby extend the overall service life thereof of the toggle joint 118. Secondly, it may be possible to better distribute a lubricant (e.g. grease or oil) that is dispensed between the outer surface 125 of the first pivot pin 124A and the first seat 127 A, second seat 127B and the third seat 127C to reduce the overall wear thereof and thereby extend the overall service life of the toggle joint 118.

Within the architecture depicted in Figure 2 there is also provided a lubricant distribution device 150, the construction and operation of which is generally known to those of skill in the art and hence will not be discussed in any great detail herein. For sake of illustration, suffice it to state that the lubricant distribution device 150 includes a pump 152 for pumping the lubricant from a lubricant tank 154 to the interfaces between the first pivot pin 124A and the first seat 127 A, the second seat 127B and the third seat 127C.

Lastly, within the architecture depicted in Figure 2 there is also provided a controller 160 for controlling the pin rotator 142 and the pump 152. As such, there is schematically shown a first connection 166 between the controller 160 and the pin rotator 142 and a second connection 168 between the controller 160 and the pump 152.

The controller 160 can be implemented as part of a controller that controls various operations of the toggle clamp 100 (FIG. 3) or more broadly the injection molding system (not shown). Alternatively, the controller 160 can be implemented as a separate computing device configured to control only the operations of the device 140 and/or the lubricant distribution device 150. The controller 160 includes internal memory 162 configured to store one or more instructions 164 for executing one or more routines, the description which will follow within the context of a method 200 of operating the device 140 to extend the service life of the toggle joint 118. With reference to FIG. 3 the toggle clamp 100 is depicted for sake of illustrating the pin rotator 142 and the first pivot pin 124A. In addition, FIG. 3 serves to illustrate that the pin rotator 142 may be linked to one or more other pivot pins. More particularly, the pin rotator 142 may be linked, for example, to a second pivot pin 124B and a third pivot pin 124C via a first belt 146 and a second belt 148, respectively.

With reference to FIG. 4 there is depicted a flow chart of a method 200 of operating the device 140 (FIG. 2) to extend a service life of the toggle joint 118 (FIG. 2) of the toggle clamp 100 (FIG. 3). The method 200 is implementable using the controller 160 (FIG. 2). The method 200 broadly includes the steps of:

Step 210:

The controller 160 directing the pin rotator 142 to selectively rotate the first pivot pin 124A within the first seat 127A of the first lever arm 120. Given the configuration of the toggle joint 118, this step also involves selectively rotating the first pivot pin 124A with respect to the second seat 127B and the third seat 127C of the second lever arm 122.

What is meant by "selectively rotate" is any driven rotation of the first pivot pin 124A with respect to the first seat 127 A of the first lever arm 120, and likewise in the present non-limiting embodiment with respect to the second seat 127B and the third seat 127C of the second lever arm 122 as well, that satisfies a pre-defined requirement. The pre-defined requirement is not particularly limited and may include, for example, a requirement to rotate the first pivot pin 124A intermittently, through a pre-defined angle of rotation (e.g. 355°), at a selected speed, in a first direction (e.g. clockwise) or in a second direction (e.g. counter-clockwise).

Moreover, the selective rotation of the first pivot pin 124A may be performed in accordance with a routine. For example, the pin rotator 142 may be selectively rotated in accordance with a wear distribution routine for selectively distributing operationally induced wear over a larger portion of an outer surface (125) of the first pivot pin 124A. The foregoing may include periodically (i.e. intermittently) repositioning the first pivot pin 124A through a pre-defined angle. The reasoning here is that wear typically happens on the contact surfaces perpendicular to the load, so by having the ability to angular-position the first pivot pin 124A, we can evenly distribute wear over time (e.g. by having a rotation of 355° instead of 360° every cycle we could evenly distribute wear over time.

The controller 160 may also include the step of directing the lubricant distribution device 150 to selectively dispense lubricant between the first seat 127 A and the outer surface 125 of the first pivot pin 124A.

Coupled with this step the pin rotator 142 may be selectively rotated in accordance with a lubrication routine for selectively distributing operationally induced wear over a larger portion of an outer surface (125) of the first pivot pin 124A. The foregoing may include, without specific limitation, periodically (i.e. intermittently) repositioning the first pivot pin 124A during clamp stroke idle time and in this way minimize force acting on it when it rotates.

It is noted that the foregoing has outlined some of the more pertinent non-limiting embodiments. It will be clear to those skilled in the art that modifications to the disclosed non-embodiment(s) can be effected without departing from the spirit and scope thereof. As such, the described non-limiting embodiment(s) ought to be considered to be merely illustrative of some of the more prominent features and applications. Other beneficial results can be realized by applying the non-limiting embodiments in a different manner or modifying the invention in ways known to those familiar with the art. This includes the mixing and matching of features, elements and/or functions between various non-limiting embodiment(s) is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise, above. Although the description is made for particular arrangements and methods, the intent and concept thereof may be suitable and applicable to other arrangements and applications.