GB2507088A

GB2507088A - Vibratory sieving apparatus with toggle clamps

Info

Publication number: GB2507088A
Application number: GB201218746A
Authority: GB
Inventors: Nigel Mainwaring
Original assignee: Russell Finex Ltd
Current assignee: Russell Finex Ltd
Priority date: 2012-10-18
Filing date: 2012-10-18
Publication date: 2014-04-23
Anticipated expiration: 2032-10-18
Also published as: GB201218746D0; GB2507088B

Abstract

A vibratory sieving apparatus (10,fig.1) has a plurality of body parts and a toggle clamp (300,fig.2) arranged, in use, to urge the body parts together to form a sieving chamber. The toggle clamp (300,fig2) features a plunger 304 slidably coupled to the toggle clamp (300,fig2) and a resilient member 606 which, in use, urges the plunger 304 into contact with at least one of the body parts. Also disclosed is a vibratory sieving apparatus (10,fig.1) with a plurality of body parts and a toggle clamp (fig.7) with a spring 606 loaded plunger 304 arranged, in use, to apply a clamping force to the body parts to hold them together. The spring loading of such toggles may result in a more consistent closing force being

Description

VIBRATORY SIEVING APPARATUS

Field of the invention

The present invention relates to a vibratory sieving apparatus.

Background of the invention

Figures 1 and 2 of the accompanying drawings schematically illustrate a known vibratory sieving apparatus (or separator) 10. The sieving apparatus 10 is shown as generally cylindrical in shape, although it will be appreciated that other shapes (such as rectangular) may be used and are available. It will also be appreciated that other configurations of sieving apparatus are known, and that the following description is equally applicable to such other sieving apparatus.

The sieving apparatus 10 has a base (or chassis) 100 mounted on a stand/frame 101, that has a number of legs 102 for standing the base 100 on the ground. The base 100 may be mounted on the stand 101 via rubber mounts, elastomeric mounts, springs or resilient members (105) that allow for the base to move/vibrate relative to the stand 101, with the stand 101 remaining stationary relative to the ground.

The base 100 defines a hole 112 into which a funnel part 120 of the sieving apparatus 10 may be inserted. The base 100 supports the funnel part in position, with a gasket 118 (e.g. of rubber or plastic) lying between the base 100 and the funnel part 120.

A sieve 130 of the sieving apparatus 10 comprises a sieve screen 132 (or mesh) which is held in an annular sieve screen frame 134. The sieve 130 rests within the funnel part 120 such that substances capable of falling/passing through the sieve screen 132 fall into and through the funnel part 120 for collection/extracting via the lower hole of the funnel part 120.

A lid/cover 140 of the sieving apparatus 10 is mounted over the sieve 130 and the funnel part 120. A gasket 136 (e.g. of rubber or plastic) surrounding the outer edge of the sieve screen frame 134 may be used to help seal the sieving apparatus 10.

In operation, substances (such as powders, liquid slurries, etc.) to be sieved enter the sieving apparatus 10 through a top hole 144 of the lid 140.

These substances may be fed into the apparatus 10 under gravity, or may be blown into the apparatus 10 under positive pressure, or may be pulled into and through the apparatus 10, e.g. by a vacuum pump. The substances fall onto the sieve screen 132.

The sieving apparatus 10 comprises a vibrator (such as a motor 107 with eccentrically mounted weights) mounted on the base 100 and arranged to vibrate the base 100 (and thereby vibrate the funnel part 120, the sieve 130 and the lid 140). Components of the substance being sieved that are small enough to pass through the sieve screen 132 drop through (or are forced/blown through or are sucked through) the sieve screen 132 into the funnel 120, which guides these components out of the bottom of the hole 112 of the base 100 for collection. The sieve 130 is arranged such that components of the substance being sieved that are too large to pass through the sieve screen 132 are moved (by the vibrations of the vibrator) towards, and exit the sieving apparatus 10 from, an outlet 146 of the lid 140.

In this way, the sieving apparatus 10 has a plurality of body parts (the base 100, the funnel 120, the sieve 130 and the lid 140) that together form a sieving chamber in which sieving occurs. Other body parts may be used in addition to, or as alternatives for, the above-described body parts. For example, multiple sieves 130 (potentially with different coarseness/fineness of mesh) may be used, with a cylindrical spacer part being used to vertically separate the sieves. This cylindrical spacer may have its own outlet (similar to the outlet 146 of the lid 140) such that components of the substance being sieved that pass through the upper sieve but that are too large to pass through the lower sieve may be extracted. Additionally, different shaped lids 140 may be used to feed the substance into the sieving apparatus 10 and the funnel 120 may be omitted or replaced by an alternatively shaped body part depending on how the components that have fallen through the sieve 130 are to be collected. Furthermore, other body parts may be included, such as a magnetic-extraction body part that extracts ferrous components of the substance being sieved. Additional gaskets (such as rubber or plastic channel or flat gaskets) may be used in conjunction with these alternative or additional body parts.

In operation, the body parts that form the sieving chamber need to be held together, as otherwise the vibration provided by the vibrator may cause the body parts to separate from each other. Such separation would provide less efficient sieving (as the substance to be sieved may fall out of/leave the sieving apparatus before it is sieved). Additionally, such a leakage of the substance being sieved may pose a risk to human operators (e.g. inhalation of dust may harm the operators; the substance may be a human-toxic substance; etc.).

Consequently, is it known to use toggle clamps (or over-centred clamps) to hold the body parts together to maintain the sieving chamber that the body parts form. Figures 3-5 of the accompanying drawings schematically illustrate a known is toggle clamp 300 that may be used for this purpose. Figure 2 illustrates the toggle clamp 300 in use on the sieving apparatus 10.

As toggle clamps and their structure are well known, they shall not be described in detail herein. Indeed, various forms of toggle clamps may be used with various clamping mechanisms employed.

As shown in figure 1, the base 100 of the sieving apparatus has a number of recesses 114 in which a respective toggle clamp 300 may be mounted (as shown in figure 2). For example, a toggle clamp 300 may be mounted in a recess 114 via a pair of bolts 302 of the toggle clamp and a corresponding pair of screw-threaded holes 116 in the base 100. Alternatively, a toggle clamp 300 may be mounted in a recess 114 via a pair of bolts 302 that pass through corresponding holes 116 in the base 100 and that are secured to the base by corresponding nuts.

The toggle clamp 300 has a plunger 304 in the form of a screw-threaded spindle 306 with a contact plate 308 (or pad) at a distal end of the spindle 306. In operation, the contact plate 308 is urged against a lip 142 of the lid 140 so asto force the lid 140, the sieve 130, the funnel 120, the base 100 and the various gaskets 118, 136 used into close contact and to prevent these body parts moving relative to each other. In this way, the lid 140, the sieve 130, the funnel 120, the base 100 and the various gaskets 118, 136 used are firmly held together so that the sieving chamber formed by the lid 140, the sieve 130, the funnel 120 and the base 100 is maintained during the sieving operation of the sieving apparatus 10.

Of course, when additional or alternative body parts are used to form the sieving chamber (as discussed above), the toggle clamp 300 acts to prevent these body parts moving relative to each other to maintain the sieving chamber formed by the body parts. Additionally, depending on the configuration of the body parts, the contact plate 308 may abut against one or more of the body parts, and not just against the lip 142 of the lid 140.

The screw-threaded spindle 306 passes through a correspondingly screw-threaded hole 314 of a pivoted arm 312 of the toggle clamp 300. It will be appreciated that the screw-threaded spindle 306 of the plunger 304 cooperates with the screw-threaded hole 314 to allow the position of the contact plate 308 relative to the arm 312 to be adjusted. This allows the height of the contact plate 308 relative to the base 100 (to which the toggle clamp 300 is mounted) to be altered/set according to the thickness, number, and type of the various body parts being used in the sieving apparatus 10. Additionally, the force applied by the contact plate 308 against the lower lip 142 of the lid 140 when the toggle clamp is engaged may be adjusted by rotating the screw-threaded spindle 306 within the hole 314.

The clamping and un-clamping operation of the toggle clamp 300 is achieved by an operator moving a handle 310 of the toggle clamp. As shown in figures 2 and 3, when the handle 310 of the toggle clamp 300 is moved downwards by the operator, the arm 312 rotates towards the sieving apparatus 10, causing the plunger 304 to rotate and the contact plate 308 to come into contact with, and be urged against, the lip 142 of the lid 140. In this way the toggle clamp 300 is placed into an engaged arrangement in which the plunger 304 applies an engagement force against the body parts (in particular the lid 140). When the handle 310 of the toggle clamp 300 is moved upwards by the operator, as shown in figures 4 and 5, the arm 312 rotates away from the sieving apparatus 10, causing the plunger 304 to rotate and the contact plate 308 to move away from, and disengage from, the lip 142 of the lid 140. In this disengaged position, the engagement force is removed and the various body parts of the sieving apparatus 10 may be separated from each other (such as for cleaning, replacement and maintenance).

The funnel part 120, the sieve 130 and the lid 140 used invariably have different thicknesses at different parts thereof, due to manufacturing tolerances and general wear and tear. This is true for other body parts that may be used in addition or as an alterative to the above-mentioned body parts. For example, if a toggle clamp 300 is engaged and disengaged multiple times at the same place relative to the lip 142 of the lid 140, then a degree of wearing and compression will occur at this location.

Additionally, if a body part is replaced, then the thickness of the replacement body part at a particular location may be different from the thicknesses at the corresponding location of the body part being replaced. This is, again, due to manufacturing tolerances and general wear and tear.

Additionally, a replacement gasket may be made of a different material that compresses differently from the previously used gasket, thereby giving a different thickness when the toggle clamps 300 are in use. Furthermore, a replacement sieve 130 may have a different thickness to the previously used sieve 130 if a different mesh is used for its sieve screen 132 (e.g. different wire thickness and attachment method).

The toggle clamps 300 may be engaged and disengaged many times (for cleaning purposes and for replacement/maintenance of various body parts of the sieving apparatus 10). As the contact plate 308 is usually made from rubber, fibre or plastic, the thickness of the contact plate 308 may change (decrease) over time due to wear and tear. The vibration of the apparatus 10 also contributes to the wearing of the contact plate 308.

As the engagement position of the contact plate 308 relative to the base is set and determined by the position of the screw-threaded spindle 306 within the hole 314, the above-mentioned variability of thicknesses of parts of the body parts and the contact plates 308 may result in one or more of the toggle clamps 300 applying an inconsistent engagement force between successive engagements of that, or those, toggle clamps 300.

Additionally, there may be a difference between the engagement forces applied by the different toggle clamps 300 being used on the sieving apparatus 10. This is due partially to the above-mentioned variability of thicknesses of parts of the body parts. It is also due to the potential for the toggle clamps 300 to be set-up differently (i.e. the position of the screw-threaded spindles 306 within their respective holes 314 may be different across the toggle clamps 300). As the position of a screw-threaded spindle 306 within its respective hole 314 is set by a human operator, there will invariably be differences between the engagement force applied by the various toggle clamps 300 when they are engaged on the sieving apparatus 10. This is especially true when different body parts (of potentially different heights) are inserted into and/or removed from the sieving apparatus 10 according to a desired sieving application.

Additionally, the use of multiple toggle clamps 300 poses its own problem.

Once a first toggle clamp 300 has been engaged, then the operator proceeds to engage the next toggle clamp 300. However, doing so is likely to result in the first (and other) toggle clamps 300 now being looser than when initially applied.

The operator must therefore check all of the toggle clamps 300 until the correct engagement force is achieved.

One of the attractions of using toggle clamps 300 is that the operators do not require tools to engage or disengage the toggle clamps 300, allowing them to assemble and disassemble the sieving apparatus 10 also without needing to use tools. However, this leaves the sieving apparatus 10 open to human error. This not only includes applying insufficient clamping force, but also includes the human operator overloading and breaking a toggle clamp 300 by using a torque applicator (e.g. increasing the length of the handle 310 by using a length of tubing or the like).

However, it is desirable for the toggle clamps 300 to provide a consistent engagement force each time that they are engaged. For example, such a consistent engagement force can ensure that sufficient engagement force is applied to prevent a substance from escaping out of the sieving chamber being formed by the body parts. Additionally, the ability to provide a more consistent engagement force eliminates an operator error that may have otherwise been introduced and helps prevent over-stressing of the body parts.

Summary of the invention

According to a first aspect of the invention, there is provided a vibratory sieving apparatus comprising: a plurality of body parts; and a toggle clamp arranged to urge the body parts together to form a sieving chamber, wherein the toggle clamp comprises a plunger slidably coupled to the toggle clamp and a resilient member for urging the plunger into contact with at least one of the body parts. The resilient member may be a spring.

According to a second aspect of the invention, there is provided a vibratory sieving apparatus comprising: a plurality of body parts; and a toggle clamp comprising a spring-loaded plunger, the plunger being arranged to apply a clamping force to the body parts to hold the body parts together.

The use of a resilient member to urge the plunger into contact with a body part, or the use of a spring-loaded plunger, ensure that a more consistent engagement/clamping force is applied by the toggle clamp to the body parts. It also reduces the likelihood of human error occurring on the part of an operator and reduces the wear on the contact plates of the toggle clamps, thereby increasing their longevity.

Embodiments of the invention may make use of a single toggle clamp.

However, preferred embodiments of the invention make use of a plurality of toggle clamps.

Brief description of the drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 schematically illustrates an exploded view of a sieving apparatus; Figure 2 schematically illustrates the sieving apparatus shown in figure 1; Figure 3 schematically illustrates a toggle clamp in an engaged position; Figure 4 schematically illustrates the toggle clamp of figure 3 in a disengaged position; Figure 5 schematically illustrates a perspective view of the toggle clamp of figure 4; Figure 6 schematically illustrates a part of the toggle clamp of the sieving apparatus according to an embodiment of the invention; and Figure 7 schematically illustrates a part of the toggle clamp of the sieving apparatus according to another embodiment of the invention.

Detailed description of embodiments of the invention In the description that follows and in the figures, certain embodiments of the invention are described. However, it will be appreciated that the invention is not limited to the embodiments that are described and that some embodiments may not include all of the features that are described below. It will be evident, however, that various modifications and changes may be made herein without departing from the broader scope of the invention as set forth in the appended claims.

A sieving apparatus 10 according to an embodiment of the invention is configured in the same manner as illustrated in figures 1-5, except that the configuration, and manner of operation, of the arm 312 and the plunger 304 are different. This will be described in more detail below.

Figure 6 schematically illustrates the arm 312 of the toggle clamp 300 of the sieving apparatus 10 according to an embodiment of the invention. The plunger 304 comprises the screw-threaded spindle 306. However, the screw-threaded spindle 306 does not pass through a correspondingly screw-threaded hole in the arm 312 (as was the case in figures 2-5). Instead, the screw-threaded spindle 306 passes through a hole 600 in the arm 312, the hole 600 not having a screw-thread that engages with the screw-thread of the spindle 306. In this way, the plunger 304 is slidably mounted within the arm 312 of the toggle clamp 300 via the hole 600, i.e. the plunger 304 is slidably coupled to the toggle clamp 300 and is moveable relative to the arm 312 of the toggle clamp 300. Preferably, the diameter of the hole 600 is such that the spindle 306 closely fits (i.e. a snug fit) inside the hole 600.

A nut 602 is provided on the screw-threaded spindle 306. The nut 602 is too large to pass through the hole 600 in the arm 312. In this way, the nut 602 limits the distance that the plunger 304 may move towards the lower lip 142 of the lid 140 when the toggle clamp 300 is engaged and prevents the plunger 304 from falling out of the arm 312.

The arm 312 has a recess 604 on the other side of the arm 312 from the nut 602. The recess 604 is preferably coaxial with the hole 600 and is of a larger diameter than the hole 600. The spindle 306 passes through the recess 604 and the hole 600.

The toggle clamp 300 comprises a spring 606 around the spindle 306.

One end of the spring 606 may abut against a top surface 608 of the contact plate 308, whilst the other end of the spring 606 may abut against an abutment surface 610 of the recess 604. The contact plate 308 and the spring 606 are sized such that the spring 606 is prevented from sliding off the spindle 306.

Additionally, the spring 606 is of a size such that it cannot pass through the hole 600.

The nut 602 may be rotated about the screw-threaded spindle 306 so as to draw the contact plate 308 towards the arm 312. If the contact plate 308 is drawn sufficiently towards the arm 312, then the spring 606 will abut against both the abutment surface 610 and the top surface 608 of the contact plate 308. If the contact plate 308 is drawn even further towards the arm 312, then the spring 606 will be in a compressed state. In this way, the toggle clamp 300 is provided with a spring-loaded plunger 304, i.e. a spring-loaded spindle 306 and contact plate 308.

In operation, when the operator engages the toggle clamp 300 so as to apply an engagement force to the lip 142 of the lid 140, the arm 312 rotates towards the sieving apparatus 10 and the contact plate 308 makes contact with the lip 142 of the lid 140. As the handle 310 of the toggle clamp is rotated downwards to its full extent, the arm 312 rotates further towards the sieving -10- apparatus 10. As such, the abutment surface 610 is forced towards the now-stationary contact plate 308, thereby compressing (or further compressing) the spring 606. The spring 606 therefore urges the contact plate 308 of the plunger 304 into contact with the lower lip 142 of the lid 140.

The spring 606 compensates for possible variations in thickness of the various body parts of the sieving apparatus. The spring allows there to be a variable distance between the contact plate 308 and the arm 312 when the toggle clamp 300 is in its engaged position. In this way, a more consistent clamping force is applied to the body parts of the sieving apparatus 10 to ensure that the body parts maintain the sieving chamber. The engagement/clamping force applied is less dependent on the set-up provided by the human operator of the sieving apparatus, i.e. is less dependent on how the human operator has positioned the spindle 304 relative to the hole 600 using the nut 602.

The clamping forced applied by the spring 606 depends on the compressed length of the spring 606. Hence, the nut 602 may be used to calibrate/adjust the compressed length of the spring 606 so as to change the initial clamping force that is applied by the toggle clamp 300.

Figure 7 schematically illustrates the arm 312 of the toggle clamp 300 of the sieving apparatus 10 according to another embodiment of the invention.

Figure 7 is similar to figure 6, and like parts have the same reference numeral and shall not be described in more detail. However, in the embodiment of figure 7, the arm 312 does not have a hole 600 so that the spindle 306 does not pass through the arm 312. Additionally, then, the toggle clamp 300 shown in figure 7 does not include the adjustment nut 602, so that the initial length of the spring 606 is preset and is not adjustable. The spindle 306 therefore need not be screw-threaded.

In figure 7, the plunger 304 is attached/held to the spring 606 (e.g. the spring 606 is secured to the top surface 608 of the contact plate 308). The spring 606 is also attached/held in the recess 610. As such, the plunger 304 is slidably coupled to the toggle clamp 300 and is moveable relative to the arm 312 of the toggle clamp 300. -11 -

In figures 6 and 7, the spring 606 is shown as having a part outside of the recess 610. However, it will be appreciated that the length of the spring 606 may be such that the spring 606 is entirely within the recess 610. In this case, the contact plate 308 may be configured to fit within, and make a close/snug fit in, the recess 610.

The spring 606 is preferably chosen (in terms of its stiffness) such that the toggle clamp 300 can achieve the expected range of clamping thicknesses. For example, if the spring 606 is too stiff, then it may not be possible for an operator, using the handle 310 of the toggle clamp 300, to compress the spring 606 sufficiently in order to achieve a small clamping thickness.

It will be appreciated that variations on the configuration shown in figures 6 and 7 are possible. For example, a resilient member other than the spring 606 could be used (such as compressible rubber tubing wrapped around the spindle 306, one or more Belleville/disc type washer springs, or one or more torsion springs). Furthermore, as mentioned above, different configurations may be used for a toggle clamp and sieving apparatus, and the above-described embodiment is an illustration of a sieving apparatus using toggle clamps with spring-loaded plungers/spindles. -12-

Claims

CLAIMS1. A vibratory sieving apparatus comprising: a plurality of body parts; and a toggle clamp arranged to urge the body parts together to form a sieving chamber, wherein the toggle clamp comprises a plunger slidably coupled to the toggle clamp and a resilient member for urging the plunger into contact with at least one of the body parts.
2. The vibratory sieving apparatus of claim 1, in which the resilient member is a spring.
3. A vibratory sieving apparatus comprising: a plurality of body parts; and a toggle clamp comprising a spring-loaded plunger, the plunger being arranged to apply a clamping force to the body parts to hold the body parts together.
4. A sieving apparatus comprising a toggle clamp substantially as herein before described with reference to figure 6 or 7.