GB2557405A

GB2557405A - A bolt

Info

Publication number: GB2557405A
Application number: GB1715877.5A
Authority: GB
Inventors: Brian Evans Howard
Original assignee: Redwood Global Ltd
Current assignee: Redwood Global Ltd
Priority date: 2016-09-30
Filing date: 2017-09-29
Publication date: 2018-06-20
Anticipated expiration: 2037-09-29
Also published as: GB201715877D0; GB2557405B; GB2554654A; GB201616641D0

Abstract

A blade fixing bolt for affixing a flywheel blade to a flywheel blade carrier comprises; a frustoconical head section, and a shank extending from the head section, wherein said shank comprises a first section located adjacent to said head section and comprising a circular cross section, a second section comprising a geometric, oblong or oval cross section, and a third section comprising a thread for engaging a nut, the cross sectional diameter of said first section being greater than or equal to the longest cross sectional dimension of said second section; and the head section and the first section arranged to position said blade fixing bolt within an aperture of said flywheel blade; wherein in said affixed position, said head section and said first section are arranged to engage with said flywheel blade and said second section is arranged to engage with said flywheel blade carrier; and wherein in the affixed position said engagement between the second section and said flywheel blade carrier is such that said flywheel blade is non-rotatable relative to said flywheel blade carrier

Description

(54) Title of the Invention: A bolt

Abstract Title: A blade fixing bolt for a flywheel blade (57) A blade fixing bolt for affixing a flywheel blade to a flywheel blade carrier comprises; a frustoconical head section, and a shank extending from the head section, wherein said shank comprises a first section located adjacent to said head section and comprising a circular cross section, a second section comprising a geometric, oblong or oval cross section, and a third section comprising a thread for engaging a nut, the cross sectional diameter of said first section being greater than or equal to the longest cross sectional dimension of said second section; and the head section and the first section arranged to position said blade fixing bolt within an aperture of said flywheel blade; wherein in said affixed position, said head section and said first section are arranged to engage with said flywheel blade and said second section is arranged to engage with said flywheel blade carrier; and wherein in the affixed position said engagement between the second section and said flywheel blade carrier is such that said flywheel blade is non-rotatable relative to said flywheel blade carrier

FIG. 1

140

1/3

141

FIG. 1

2/3

FIG. 2

3/3

FIG. 3

A Bolt

Field of the Invention

The present invention relates to a bolt, more specifically a blade fixing bolt for a flywheel mounted blade, and more specifically still to a bolt for a flywheel blade comprising a shank that comprises a geometric or oval cross section. In particular, the blade fixing bolt may provide a locating function.

Background to the Invention

In chippers, cutters and other vegetation shredding equipment, blades may be used to break down bulk vegetation in to pieces sized for disposal. In any such machine, to ensure an efficient chipping process, a plurality of blades is typically mounted on a rotating flywheel. Here, each blade is affixed to a circular flywheel such that its cutting edge lies parallel to a radius of that same flywheel. As such, any rotation of the flywheel results in the concomitant rotation of the blades and the reduction of all contacted vegetation. Typically, the rotation of the flywheel is powered by a petrol or diesel motor. In this way, any vegetation may be reliably chipped at a remote location, distant from any source of electrical power, although the use of a battery powered chipper remains a possibility.

Whilst any such chipper may initially provide a satisfactory solution to the reduction and disposal of vegetation, the nature of the material for disposal may rapidly degrade the performance of the blades. Any vegetation reduced by the chipper is unlikely to be completely free of soil and stones, and the vegetation itself is likely to include relatively tough materials. Therefore, it is unsurprising any blades used within the chipper become blunt, worn and unusable well within the expected lifetime of the chipper as a whole.

To combat this blunting of the blades, modern chipping machines usually include removable blades. Here, the blades are most commonly securely fixed to the flywheel using bolts, allowing the blades to be removed and replaced where required.

Where a bolt is used to affix a blade to the flywheel, both the blade itself and the flywheel typically include a matching pattern of apertures. Each aperture in the blade is then overlaid onto a corresponding aperture in the flywheel, and a bolt inserted through both the blade and the flywheel via the aligned apertures. The complete passage of the bolt through the apertures is prevent by an enlarged head at one end of the bolt, this head sized such that it is unable to pass through the aperture in either the blade or the flywheel.

After insertion of the bolt into the apertures, a nut is placed on the end of the bolt distal from the head. This nut may be secured on to the bolt via a screw thread. Where a screw thread is used, the bolt and nut may be tightened using an indentation in the head of the bolt suitable for engagement with a screwdriver, Allen key or torx fitting, whilst a spanner, ratchet or similar is used to hold the nut in place. In this manner, the nut and bolt may be tightened to hold the blade in position on the flywheel. Alternatively, the bolt may screw directly into a thread located within the aperture on the flywheel.

Whilst such a solution allows worn, damaged and blunted blades to be removed from the flywheel, the use of bolts is not without issue. During the operation of the chipper, debris from the vegetation reduced is propelled over all surfaces in the vicinity of the cutting blades and, as a result, becomes trapped in the indentation located in the head of the bolt. In such a situation, it becomes more difficult for the user to remove the blade, and the overall replacement process may become very time consuming.

Additionally, this effect may be compounded if not all debris is removed from the indentation before removal of the bolt is attempted, and the indentation becomes misshapen or rounded off. Any deformation of the indentation further increases the difficulty of removing a blade. Finally, if the screw thread is located within the flywheel aperture itself, debris may enter this aperture and damage the screw threads during the affixation or removal of a blade, potentially resulting in the need to replace the flywheel, a relatively costly undertaking.

Other solutions are provided by bolts such as those found in, for example, US 2012/047752 A1, CN 204560242 U, US 2010/115905 A1, CA 2477180 A1, and CA 2615304 A1. These examples all have a very specific function, which is to loosely retain a rotating flail type blade, the bolts comprising a blade pivot and shoulder to maintain a space to facilitate blade rotation. These previous fixing systems, such as those developed to loosely retain a rotating flail type blade, are used purely as a blade pivot and shoulder to maintain a space to facilitate blade rotation. This confers a disadvantage to such solutions when applied to blade-fixing applications, such as in fixing a flywheel blade to a flywheel blade carrier in a non-rotatable fashion with minimal effort and maximum robustness to repeated removal and reattachment of a blade, rather than flail-type blade applications.

It is therefore desirable to provide a blade-fixing bolt enabling simpler repeated assembly and disassembly of a flywheel blade and a flywheel blade carrier, wherein said blade-fixing bolt is robust to repeated assembly and disassembly of said flywheel blade and said flywheel blade carrier.

Summary of the Invention

The present invention as defined in the appended claims provides a bolt and system capable of connecting a blade to a flywheel without the disadvantages of the prior art.

According to a first aspect of the present invention, there is provided a blade fixing bolt arranged to affix a flywheel blade to a flywheel blade carrier in an affixed position, said blade fixing bolt comprising; a frustoconical head section, and a shank extending from the head section, wherein said shank comprises a first section located adjacent to said head section and comprising a circular cross section, a second section located adjacent to said first section and comprising a geometric, oblong or oval cross section, and a third section located adjacent to said second section and comprising a thread for engaging a nut, said third section being proximal to an end of said shank distal to said head section; the cross sectional diameter of said first section being greater than or equal to the longest cross sectional dimension of said second section; and the head section and the first section arranged to position a portion of said blade fixing bolt within an aperture of said flywheel blade; wherein in said affixed position, said head section and said first section are arranged to engage with said flywheel blade and said second section is arranged to engage with said flywheel blade carrier; and wherein in the affixed position said engagement between the second section and said flywheel blade carrier is such that said flywheel blade is non-rotatable relative to said flywheel blade carrier.

In this way, there is provided a blade fixing bolt capable of affixing a flywheel blade to a flywheel blade carrier without the use of a screwdriver, Allen key or torx fitting. During use, the bolt is inserted through corresponding apertures in the blades and the flywheel, wherein the geometric or oval second section of the bolt engages with a specifically sized aperture in said flywheel blade carrier to prevent the rotation of the bolt. A nut may then be screwed on to the third section of the bolt to hold the bolt, and thus the blade, in place. Additionally, such a bolt enables the installation of the bolt with one hand, whilst the second hand holds the blade, increasing the safety of blade installation. The head section is frustoconical. Preferably, the head section is tapered. As such, the head section and the first section may preferably be used to self-locate or selfcenter said blade fixing bolt within an aperture of said flywheel blade.

Preferably, during said affixing of a flywheel blade to said flywheel blade carrier in said affixed position, none of the blade fixing bolt, the flywheel blade or the blade carrier are deformed.

Preferably, the blade fixing bolt of the present invention is such that said affixing of a flywheel blade to said flywheel blade carrier in said affixed position is reversible. More preferably, the blade fixing bolt of the present invention is such that said affixing of a flywheel blade to said flywheel blade carrier in said affixed position and/or reversal of said affixing is repeatable. Most preferably, during said repeated affixing and/or reversal of said affixing, none of the blade fixing bolt, the flywheel blade or the blade carrier are deformed.

Preferably the engagement of the head section and first section of the blade fixing bolt with the flywheel blade, and/or the engagement of the second section of the blade fixing bolt with the flywheel blade carrier, is such that none of the blade fixing bolt, the flywheel blade or the blade carrier are deformed.

Preferably the positioning of a portion of the blade fixing bolt within said aperture of said flywheel blade by the head section and the first section provides a self-centering function of the blade fixing bolt, wherein said portion of the blade fixing bolt is centered within said aperture of said flywheel blade. Preferably this function enables easier affixing and reversal of affixing of said flywheel blade to said blade carrier, wherein said affixing and reversal of affixing is preferably repeatable.

Preferably, the head section, first section, second section and third section are positioned in sequence from the proximal to distal end of the bolt.

Preferably, the purpose of the blade fixing bolt of the first aspect of the present invention is to firmly affix a blade to a flywheel. In preferable embodiments, depending upon blade size there would be two or more bolts. Preferably, apertures comprised within a flywheel blade precisely match the cross sectional configuration of the head section and the first section of the blade fixing bolt. Preferably, during the operation of affixing said flywheel blade to said flywheel blade carrier, said apertures in said flywheel blade are preferably precisely aligned with corresponding apertures comprised within said flywheel blade carrier. Preferably said apertures comprised within said flywheel blade carrier enable a transition fit of said second section of said blade fixing bolt, and more preferably have the same cross section as said second section. Preferably during the operation of affixing said flywheel blade to said flywheel blade carrier, a washer and nut are preferably fitted and tightened onto said third section, enabled by the thread comprised within said third section.

Thus, most preferably the blade is securely fixed with accuracy due to the preferable enhanced locating function conferred by the head section and the first section of said blade fixing bolt.

In preferable embodiments, owing to the geometric, oblong or oval cross section of said second section, a nut can be tightened onto and loosened from said third section repeatedly using a single tool, and in such embodiments, repeated tightening and loosening is preferably enabled with no loss in functionality or fit or position.

Previously available bolts, such as those developed to loosely retain a rotating flail type blade, are used purely as a blade pivot and shoulder to maintain a space to facilitate blade rotation rather as an accurate location device.

Furthermore, the functionality provided by many of the bolts of the currently available technology have no accurate self centering locating function. In many currently available examples, the function of bolt sections, such as those often found with a square cross section immediately below the head of the bolt, is to pull into wood as the bolt is tightened. In such cases, these sections therefore assist in rotation prevention by maximising friction within wood. The square cross-section of the second section of the present invention, by contrast, works in conjunction with the head section and the first section in providing an accurate locating functionality, while also providing an accurately sized cross section, said cross section sized to correspond to an aperture in said blade carrier such that rotation of said flywheel blade relative to said flywheel blade carrier is inhibited.

Coach-type bolts of the currently available technology are not available to serve applications served by the blade-fixing bolt of the present invention and described herein, and prior type of bolts could not be used to accurately or safely fix a blade to a flywheel as described and set out herein.

Preferably a first face of the head section that opposes the shank is substantially planar. Preferably, the first face of the head section is substantially planar across its entire surface. Alternatively, it may be preferable for the first face to be curved, more preferably smoothly curved, still more preferably a spherical cap. Alternatively, the first face may be a segment of a sphere.

Preferably, the second section comprises a greater length of shank than the first section. More preferably, the second section is two to eight times longer than the first section. Still more preferably, the second section is 4 to 6 times the length of the first section. Most preferably, the second section is five times the length of the first section.

Preferably, the second section comprises a geometric cross section with chamfered corners. Preferably the second section comprises a cross section with rounded corners. More preferably, the second section comprises a cross section with rounded corners, wherein each corner has a constant radius of curvature. Still more preferably, the second section comprises a plurality of rounded corners, each rounded corner having the same radius of curvature.

Preferably, the second section comprises a rectangular cross section. More preferably, the second section comprises a square cross section. Alternatively, the second section comprises a triangular, rhomboid, trapezoid, pentagonal, hexagonal, heptagonal, octagonal, nonagonal, decagonal or dodecagonal cross section. Alternatively the second section comprises an elliptical cross section.

Preferably, the bolt comprises carbon steel. Preferably, the bolt is plated, and the plating comprises zinc. Preferably, the plating comprises nickel. Preferably the plating comprises both zinc and nickel.

Preferably a portion of the blade fixing bolt provides for location within an aperture of a said flywheel blade.

In accordance with a second aspect of the present invention, there is provided a kit of parts comprising, a flywheel blade carrier, and two or more blade fixing bolts according to the first aspect of the present invention, wherein said flywheel blade carrier comprises at least two apertures sized to engage said second section of said blade fixing bolts.

Preferably, the kit of parts further comprises a flywheel blade, and said flywheel blade comprises at least two apertures sized to engage said first section or head section of said blade fixing bolts.

Preferably, the kit of parts further comprises at least two blade fixing nuts, and said blade fixing nuts sized to engage said thread on said third section of said blade fixing bolts.

Detailed Description

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:

Figure 1 is an isometric view of a blade fixing bolt in accordance with the first aspect of the present invention and comprised within an embodiment of a kit of parts according to the second aspect of the present invention;

Figure 2 is a side view of the blade fixing bolt of Figure 1; and

Figure 3 is a cross sectional view of the blade fixing bolt of Figure 1 and Figure 2.

Referring to Figure 1 of the drawings, there is shown a bolt 100 in accordance with the present invention. Here, the bolt 100 comprises a head section 110, a first section 120, a second section 130 and a third section 140. The first section 120, second section 130 and third section 140 together form a shank 150 that extends from the head portion 110 along a longitudinal axis of the bolt 100. The bolt 100 is made from a carbon steel, plated in zinc to reduce corrosion.

Referring to each section in turn, the head section 110 is frustoconical in shape, tapering down from a first face 111 at a proximal end of the bolt to the junction of the head section 110 and the first section 120. As shown in Figure 1, this taper is smooth and linear, resulting in a consistent and constant reduction of the cross section of the head portion 110, where this cross section is taken at a plane perpendicular to the longitudinal axis of the bolt 100. Such a taper here occurs over a distance of 7.5 mm, resulting in the sides of the head piece 110 being angled at 45° to the longitudinal axis of the bolt 100.

The first face 111 is located at the proximal end of the bolt 100, and is substantially planar, the surface of the face lying in a plane perpendicular to the longitudinal axis of the bolt 100. Figure 1 depicts the entirety of the surface of the first face 111 lying in a plane perpendicular to the longitudinal axis of the bolt 100.

The distal end of the head section 110 is connected to the first section 120. The first section has a diameter that is smaller than that of the head section 100, and has a generally circular cross section where this cross section is taken at a plane perpendicular to the longitudinal axis of the bolt 100. The first section 120 extends for a relatively short distance along the longitudinal axis of the bolt 100, here for around 3 mm. Additionally, the first section 120 has a constant cross section throughout, forming a cylinder.

The distal end of the first section 120, is connected to the second section 130. In Figure 1, the second section 130 is illustrated as having a geometric cross section where this cross section is taken at a plane perpendicular to the longitudinal axis of the bolt 100. More specifically, the cross section of the second section 130 is a square with chamfered or rounded corners, although other geometric shapes, ovals, ellipses and oblongs are also envisaged.

The edges of the second section 130 that lie parallel to the longitudinal axis of the bolt 100 are rounded. The edges are rounded to form a curve with a constant radius of curvature, to form a second section 130 with a fourfold axis of rotational symmetry, wherein the longitudinal axis of the bolt 100 forms the axis of symmetry.

The second section 130 has a longest cross sectional dimension of equal length to the cross sectional diameter of the first section 120. Additionally, the second section 130 extends for 15 mm along the longitudinal axis of the bolt 100. As such, the second section 130 is around five times the length of the first section 120.

At its distal end, the second section 130 tapers and connects to the third section 140. This tapered section extends for around 4 mm along the longitudinal axis of the bolt 100, and the third section 140 extends for around 16 mm along the longitudinal axis of the bolt. The third section 140 has a circular cross section where this cross section is taken at a plane perpendicular to the longitudinal axis of the bolt 100. Additionally, a screw thread extends around the outer surface of the third section 140, such that the third section 140 is capable of engaging with bolt or other threaded fastening means. The edge of the bolt 100 at the distal end of the third section 140 is also chamfered or rounded, smoothing the transition from the side of the third section 140 to the distal face 141 of the bolt 100.

The aforementioned features of this embodiment of the invention are also illustrated in Figure 2. Figure 2 depicts the bolt 100 from a side view, illustrating the head section 110 and the formation of the shank 150 from the first section 120, the second section 130 and the third section 140. The relative dimensions of each section are depicted, with the greater diameter of the head section 110, and its taper into the first section 120, clearly represented. Figure 2 also illustrates that the third section 140 has a smaller cross sectional diameter than the first section 120, where these cross sections are taken at a plane perpendicular to the longitudinal axis of the bolt 100.

The bolt 100 may be further viewed in Figure 3, where a cross section along the longitudinal axis of the bolt 100 is reproduced. Here it can be seen the bolt has an axis of rotational symmetry along the centre of its longitudinal axis, shown by line 160. The shank 150 and the head section 110 are again depicted.

In use, the bolt 100 affixes a blade to a blade carrier on a flywheel in a wood chipping machine. Here, both the blade and the blade carrier contain a matching pattern of apertures, the apertures in the blade being circular and the apertures in the blade carrier being sized to receive and correspond to the second section 130 of the bolt 100. To install a bolt 100, an aperture in the blade is overlaid onto a corresponding aperture in the blade carrier, and a bolt inserted through both the blade and the blade carrier via the aligned apertures.

After insertion, when the first section 120 and the head section 110 abut the blade, they act as locators for the blade. The bolt is positioned such that it cannot rotate around its longitudinal axis as the second section 130 is located within the aperture of the blade carrier and so acts as a locator in the blade carrier. The complimentary, interlocking shapes of the second section 130 and the aperture in the blade carrier prevent any rotation and create an original bolt design.

The third section 140 protrudes from the blade carrier such that the screw thread is accessible. To complete the installation of the bolt 100, a nut is threaded on to the screw thread and tightened to maintain the bolt 100 in position, to ensure the head section 110 and the first section 120 remain abutting the blade, and that the second section 130 remains within the aperture of the blade carrier. When removal of the blade is required, this nut is loosened, and the bolt 100 removed from both apertures. Tightening and loosening of the nut may be undertaken one handed, the user’s second hand used to hold the blade to prevent its fall, increasing the safety of blade installation and removal. In this embodiment of the invention the head 110 and first section 120 along with second section 130 can be considered to provide the innovative locating function. The overall positioning and locking is provided by the complimentary, interlocking shapes of the second section 130 and the aperture in the blade carrier which prevent any rotation between the blade and the blade carrier.

In most preferable embodiments, two or more bolts are used to affix a flywheel blade to a flywheel blade carrier, wherein in an affixed position, the flywheel blade does not rotate relative to the flywheel blade carrier. As such, in said preferable embodiments, two or more nuts used to engage said two or more bolts in the fixing of said flywheel blade to said flywheel blade carrier may be tightened and untightened repeatedly using a single tool.

Clauses

1. A bolt for a flywheel mounted blade, said bolt comprising; a head section, and a shank extending from the head section, wherein said shank comprises a first section comprising a circular cross section, a second section comprising a geometric, oblong or oval cross section, and a third section comprising a thread for engaging a nut;

wherein the cross sectional diameter of said first section is greater than or equal to the longest cross sectional dimension of said second section.

2. A bolt according to clause 1, wherein said head section is frustoconical.

3. A bolt according to clause 1 or clause 2, wherein said first section is adjacent to said head section.

4. A bolt according to clause 3, wherein said second section is adjacent to said first section.

5. A bolt according to clause 4, wherein said third section is adjacent to said second section.

6. A bolt according to any preceding clause, wherein said third section is proximal to a distal end of said shank.

7. A bolt according to any preceding clause, wherein a first face of said head section that opposes said shank is substantially planar.

8. A bolt according to any preceding clause, wherein said second section comprises a greater length of said shank than said first section.

9. A bolt according to any preceding clause, wherein said second section comprises a geometric cross section with chamfered or rounded corners.

10. A bolt according to any preceding clause, wherein said second section comprises a square cross section.

11. A bolt according to any preceding clause, wherein said bolt comprises carbon steel.

12. A bolt according to any preceding clause wherein said bolt is plated, said plating comprising zinc.

13. A bolt according to any preceding clause, wherein said bolt is a blade fixing bolt.

14. A kit of parts comprising, a blade carrier, and a bolt as claimed in any proceeding clause, wherein said blade carrier comprises at least one aperture sized to engage said second 10 section of said bolt.

15. A kit of parts according to clause 14, wherein the kit of parts further comprises a blade, and said blade comprising at least one aperture sized to engage said first section or head section of said bolt.

16. A kit of parts according to clause 14 or clause 15, the kit of parts further comprising a nut, and said nut sized to engage said thread on said third section of said bolt.

Claims

1. A blade fixing bolt arranged to affix a flywheel blade to a flywheel blade carrier in an affixed position, said blade fixing bolt comprising;

a frustoconical head section, and a shank extending from the head section, wherein said shank comprises a first section located adjacent to said head section and comprising a circular cross section, a second section located adjacent to said first section and comprising a geometric, oblong or oval cross section, and a third section located adjacent to said second section and comprising a thread for engaging a nut, said third section being proximal to an end of said shank distal to said head section;

the cross sectional diameter of said first section being greater than or equal to the longest cross sectional dimension of said second section; and the head section and the first section arranged to position a portion of said blade fixing bolt within an aperture of said flywheel blade;

wherein in said affixed position, said head section and said first section are arranged to engage with said flywheel blade and said second section is arranged to engage with said flywheel blade carrier; and wherein in the affixed position said engagement between the second section and said flywheel blade carrier is such that said flywheel blade is non-rotatable relative to said flywheel blade carrier.

2. A blade fixing bolt according to claim 1, wherein a first face of said head section that opposes said shank is substantially planar.

3. A blade fixing bolt according to claim 1 or claim 2, wherein said second section comprises a greater length of said shank than said first section.

4. A blade fixing bolt according to any preceding claim, wherein said second section comprises a geometric cross section with chamfered or rounded corners.

5. A blade fixing bolt according to any preceding claim, wherein said second section comprises a square cross section.

6. A blade fixing bolt according to any preceding claim, wherein said bolt comprises carbon steel.

7. A blade fixing bolt according to any preceding claim wherein said bolt is plated, said plating comprising zinc.

8. A blade fixing bolt according to any preceding claim, further wherein a portion of the blade fixing bolt provides for location within an aperture of a said flywheel blade.

9. A kit of parts comprising, a flywheel blade carrier, and two or more blade fixing bolts as claimed in any preceding claim, wherein said flywheel blade carrier comprises at least two apertures sized to engage said second section of said blade fixing bolts.

10. A kit of parts according to claim 9, wherein the kit of parts further comprises a flywheel blade, and said flywheel blade comprises at least two apertures sized to engage said first section or head section of said blade fixing bolts.

11. A kit of parts according to claim 9 or claim 10, the kit of parts further comprising at least two blade fixing nuts, and said blade fixing nuts sized to engage said thread on said third section of said blade fixing bolts.

Intellectual

Property

Office

Application No: GB1715877.5