Patent Publication Number: US-8973273-B2

Title: Foldable chisel

Description:
BACKGROUND 
     1. Field 
     The present invention is generally related to chisels. More particularly, the application relates to foldable chisels. 
     2. Description of Related Art 
     Chisels typically include a blade with a cutting edge and one or more handles. The one or more handles are adapted for carrying the chisel and for being struck by another tool, such as a hammer, to drive the cutting edge to carve, shave, or cut a work piece. When the chisel is being transported, it may be carried in a bag to protect the blade against damage and to protect users from the cutting edge of the blade. 
     SUMMARY 
     One embodiment comprises a chisel having: a blade; a first handle rotatably coupled to the blade and forming a first channel adapted to receive a first side of the blade; and a a second handle rotatably coupled to the blade and forming a second channel adapted to receive a second side of the blade opposite the first side of the blade. The first handle and second handle are rotatable between an open position in which the blade is substantially exposed and a closed position in which the blade is at least partially contained in the first channel and the second channel. The first handle and the second handle comprise a rotatable coupling such that the first handle and the second handle rotate with one another in opposite directions between the closed position and the open position. The foldable chisel further comprises an over-center structure configured to impede rotation of the first handle and the second handle from the closed position toward the open position. 
     One embodiment comprises a chisel having a blade; a first handle rotatably coupled to the blade; and a second handle rotatably coupled to the blade. The first handle comprises a first interlocking component and forms a first channel adapted to receive a first side of the blade. The second handle comprises a second interlocking component and forms a second channel adapted to receive a second side of the blade opposite the first side of the blade. The first handle and the second handle are rotatable between an open position in which the blade is substantially exposed and a closed position in which the blade is at least partially contained in the first channel and the second channel. The first interlocking component and the second interlocking component are adapted to releasably couple the first handle and the second handle when the two handles are rotated to the open position. 
     Aspects of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. In one embodiment of the invention, the structural components illustrated herein can be considered drawn to scale. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. It shall also be appreciated that the features of one embodiment disclosed herein can be used in other embodiments disclosed herein. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a perspective view of a foldable chisel in an open position; 
         FIG. 1B  shows a perspective view of the foldable chisel of  FIG. 1A  in a closed position; 
         FIG. 2  shows a cross section view taken along a plane parallel to a top and bottom surface of the foldable chisel of  FIG. 1A ; 
         FIG. 3  shows a top view of the foldable chisel of  FIG. 1A  in the closed position; 
         FIG. 4  shows an exploded perspective view of two handles of the foldable chisel of  FIG. 1A . 
         FIG. 5A  shows a top view of the foldable chisel of  FIG. 1A  in the open position; 
         FIG. 5B  shows a cross section view taken along line  5 B- 5 B in  FIG. 5A  (looking away from the blade). 
         FIG. 5C  shows an expanded view of the cross section view shown in  FIG. 5B . 
     
    
    
     DETAILED DESCRIPTION 
     Referring now more particularly to the drawings,  FIGS. 1A and 1B  are perspective views of a foldable chisel  100  in accordance with one embodiment of the invention.  FIG. 1A  shows foldable chisel  100  in an open, or unfolded position, while  FIG. 1B  shows foldable chisel  100  in a closed, or folded position. Chisel  100  includes an elongated blade  110  and handles  120  and  130  that are both coupled to blade  110 . 
     Blade  110  may have one or more cutting edges adapted to, for example, carve, shave, or cut work pieces. As shown in  FIG. 1A , blade  110  may have a beveled front cutting edge  111 , a chamfered left side  112  and chamfered right side  113 , and a back side  114 . In some embodiments, blade  110  may have one or more cutting edges in addition to or other than front cutting edge  111 , such as a cutting edge on left side  112  or right side  113  of the blade  110 . The cutting edge may be beveled or non-beveled. In some embodiments, left side  112  or right side  113  may be directly adjacent to a top surface  115  or bottom surface  116  without a chamfer between the side and top or bottom surfaces. The left side  112  or right side  113  may be orthogonal to top surface  115  or bottom surface  116 , as shown in  FIG. 1A , or may be oblique to the top surface  115  or bottom surface. The left side  112  or right side  113  may be orthogonal to front edge  111  or back side  114 , as shown in  FIG. 1A , or may be oblique to the front edge  111  and back side  114 . For example, blade  110  may be shaped as a trapezoid that widens from back side  114  towards front edge  111 . In some embodiments, opposite sides of blade  110  may not be parallel. For example, relative to bottom surface  116 , top surface  115  may slant toward front edge  111  or may slant toward left side  112  or right side  113  to form, for example, a cutting side edge. 
     Blade  110  may have a width W that is constant along blade  110  or that varies along the blade  110 . For example, as shown in  FIG. 1A  and  FIG. 2 , the width of blade  110  may narrow at a neck between a pair of concave-shaped recesses and may widen at both the front edge  111  and back side  114  of the blade. At the back side  114 , blade  110  may widen on each side to form a circular contour that may match a contour of gears provided on chisel handles, which are discussed more below, coupled to blade  110 . In another example, as discussed above, blade  110  may form a trapezoidal shape. In another example, the left side  112  and right side  113  may curve outward such that the blade  110  has a semi-circular or a semi-elliptical shape. In some embodiments, blade  110  may be substantially as wide as a total width of handles  120  and  130 , while in other embodiments blade  110  may be substantially narrower or substantially wider. 
     Each of handles  120  and  130  (and particularly the rear ends  125 ,  135  thereof) may be configured for being struck by another tool or striking instrument, such as a hammer. In some embodiments, the rear of each handle may comprise an end cap that may be made of materials (e.g., steel) known to withstand impact from the striking instrument. Alternatively, each handle may be entirely formed from a material suitable for being struck. Each handle may be made of metal, wood, a composite material, or a synthetic material. Each handle may be contoured, shock absorbent, or ergonomic. For example, handles  120  and  130  may each have a recessed portion  128  and  138 , respectively, adapted for gripping handles  120  and  130  when they are to be pivotally moved from the deployed position shown in  FIG. 1A  to the closed or storage position illustrated in  FIG. 1B . 
     Each of handles  120  and  130  may be coupled to blade  110  in a manner that allows each of the handles to rotate relative to the blade. The rotation allows the two handles to collapse around the blade, reducing the size of foldable chisel  100  and making storage and transport of the chisel  100  more convenient. In the example shown in  FIG. 1A , each of handles  120  and  130  may form a hinge configuration with blade  110 . Two pins  119 A and  119 B may protrude from top surface  115  and may each be fitted into a complementary slot  129 A on handle  120  or a complementary slot  139 A on handle  130 , as seen in  FIG. 1B  and  FIG. 4 . Each pin  119 A or  119 B may form a pivot around which its respective handle may rotate. In another example, a pin may protrude from each of handles  120  and  130 . Each pin may be fitted into a slot formed on blade  110 . In some cases, the pin may form an axle that extends through the entire blade. In another example, each handle may be rotatably coupled to the blade  110  through a ball and socket configuration. Bearings, bushing, or lubrication, such as Teflon®, may be located at an interface between the handles  120 ,  130  and the blade  110  to reduce rotational friction. In some embodiments, each handle may be rotatably coupled to blade  110  at both top surface  115  and bottom surface  116 . For example, handle  120  may comprise two slots  129 A and  129 B, as seen in  FIG. 4 . As seen in  FIG. 1B  and  FIG. 4 , slot  129 A may fit around pin  119 A on the top surface  115  of blade  110 , while slot  129 B may fit around pin  119 C on bottom surface  116  of blade  110 . In the example, handle  130  may comprise two slots  139 A and  139 B, as seen in  FIG. 4 . As seen in  FIG. 1B  and  FIG. 4 , slot  139 A may fit around pin  119 B on top surface  115  of blade  110 , while slot  139 B may fit around pin  119 D on the bottom surface  116  of blade  110 . In other embodiments, each handle may be rotatably coupled to blade  110  on only one side of the blade  110 . For example, blade  110  and handles  120  and  130  may be rotatably coupled at top surface  115  of the blade  110 , while bottom surface  116  may be flat and abutting an inner wall of handle  120  and an inner wall of handle  130 . 
     Each of handles  120  and  130  may be rotatable between the open, or unfolded position illustrated in  FIG. 1A  and the closed, or folded position illustrated in  FIG. 1B . The folded position is more compact for storage purposes. In some embodiments, as the handles  120  and  130  are rotated toward the closed position, channels  124  and  134  formed in the handles may receive sides of the blade. For example, channel  124  may receive right side  113  of blade  110  and channel  134  may receive left side  112  of blade  110 . Each channel may have a length that is substantially the same, longer, or substantially longer than the length L of blade  110 . The length of one of the channels  124 ,  134  may further be substantially the same, shorter, or substantially shorter than the handle on which it is formed. 
     Each channel may have a height H that is substantially the same, greater, or substantially greater than a thickness of blade  110 . In some embodiments, the height H of the channel may be uniform, as shown in  FIG. 1A , or may vary along the length of the handles. In one example, if blade  110  decreased in thickness from back side  114  toward front edge  111 , each of channels  124  and  134  may decrease in height along the length of the handle, from a side of the handle near back side  114  toward opposite side  125  or  135  of the handle. The height decrease may have a first slope and a second, steeper slope. The second, steeper slope may follow a slope of the beveled surface near front edge  111  and the first, shallower slope may follow a slope of a surface of blade  110  between the beveled surface and back side  114 . In some embodiments, the height H of the channel may vary along the width of the handles. In one example, if blade  110  has a beveled or chamfered side, as illustrated in  FIG. 1A , the height H of each of channels  124  and  134  may be greatest at a mouth of the channel and may decrease along the width of its handle, forming a shape that substantially matches the chamfered or beveled shape of the left side  112  and right side  113  of the chisel. 
     Channels  124  and  134  each have a depth D that may together be sufficiently deep to contain at least a partial portion of blade  110 . For example, each of channels  124  and  134  may have a depth D that is about half the width of blade  110 . When the two handles are folded to the closed position, blade  110  may be substantially contained in a combination of channels  124  and  134 . In another example, each of channels  124  and  134  may have a depth D that is substantially less than the width of blade  110  (e.g., one-third or one-quarter of the width of blade  110 ), such that only a partial portion of the blade  110  (e.g., two-thirds or one-half of blade  110 ) is contained in the combination of channels  124  and  134 . In some embodiments, each channel may have a depth that varies along the length of its handle. For example, if blade  110  widened from back side  114  toward front edge  111 , each channel  124 ,  134  may be shallowest near back side  114  and may deepen toward the opposite side  125 ,  135  of the handle. The slope of deepening may follow a slope at which blade  110  widens, or may be steeper or shallower. In some embodiments, each channel may have a depth that varies along a top-to-bottom direction of the handles. The depth may be varied, for example, to match the shape of the blade  110  of  FIG. 1 , which has a chamfered side. The channel may be shallowest near a top surface of the handles  120  and  130  and deepest near their bottom surface to accommodate the wider bottom surface  116  of blade  110 . The same shape may be achieved by varying the height H of the channel, as discussed above. 
     In some embodiments, when handles  120  and  130  are rotated to the open position, channels  124  and  134  may be separated by a wall on a back side of handle  120  and a wall on a back side of handle  130 . In some embodiments, the back sides of handles  120  and  130  may have no wall, or may have a wall with an opening, such that channels  124  and  134  form a contiguous cavity when the handles are rotated to the open position. 
     Handles  120  and  130  comprise a coupling that generates synchronized movement among the two handles. In one embodiment, handles  120  and  130  have a rotatable coupling that can take the form of two gears. For example, as shown in the figures, a gear  122  and a gear  132  are provided on handles  120  and  130 , respectively. Gears  122  and  132  operatively engage and substantially synchronize rotation of the two handles. For example, gears  122  and  132  may force handles  120  and  130  to rotate in opposite directions at substantially the same rate. Each gear may be a separate component coupled to its handle or may be part of its handle&#39;s main body. Gears  122  and  132  may operatively engage each other through one or more gear teeth on each gear. For example, the gear teeth of gear  122  may mesh with the gear teeth of gear  132 , as shown in  FIG. 1A . In another example, the one or more gear teeth of gears  122  and  132  may mesh with one or more gear teeth of one or more intervening gears placed between gears  122  and  132 . Each gear  122  and  132  may have five gear teeth, as shown in  FIG. 1A , or may have one, three, six, seven, or any other number of gear teeth. Each gear may have a diameter substantially the same as the width of its handle, as shown in  FIG. 1A , or may have a diameter that is substantially greater or less than the width of its handle. In some embodiments, while gears  122  and  132  may be in contact with blade  110 , remaining portions of handles  120  and  130  may have a clearance (e.g., 0.5 mm) from a top  115  or bottom surface  116  of blade  110 . 
     In some embodiments, such as one shown in  FIG. 4 , handles  120  and  130  may each comprise multiple gears. The gears may mesh at multiple surfaces of blade  110 , such as top surface  115  and bottom surface  116 . In some embodiments, each handle may comprise only one gear. The gears, such as gears  122  and  132 , comprise one embodiment of the rotatable coupling of handles  120  and  130 . In some embodiments, rotatable coupling  120  and  130  can also be a different type of rotatable coupling, such as a four-bar linkage, pivotal coupling, or other type of coupling that generates synchronized movement of the handles  120 ,  130 . 
     The handles  120  and  130  have an over-center structure  140  that impedes rotation of the two handles away from the closed position. Thus, when handles  120  and  130  are folded to the closed position, the over-center structure inhibits the handles from being accidentally unfolded. The over-center structure  140  requires application of a predetermined force to enable the handles to overcome a force that tends to keep the handles closed.  FIG. 3  shows one example of over-center structure, which in this embodiment takes the form of a detent  140  that is formed on a recessed portion of gear  132 . Other types of over-center structures, such as that which may be used with a four-bar linkage and spring structure can also be used. The recessed portion receives a gear tooth  122 A of gear  122  when handles  120  and  130  are at or near the closed position. The detent  140  may comprise a bulge  142  that protrudes from the recessed portion. As handles  120  and  130  are near the closed position, like that shown in  FIG. 3 , gear tooth  122 A may engage the bulge  142  of detent  140 , causing gear tooth  122 A to be squeezed against the bulge  142 . The force exerted by gear tooth  122 A and bulge  142  against each other may impede rotation of the gears and require a user to overcome the detent  140  by applying a rotational force that is sufficient to squeeze gear tooth  122 A and bulge  142  of the detent  140  past each other. The detent  140  impedes the rotation until bulge  142  of detent  140  passes over the center of gear tooth  122 A. After passing over the over-center position, the handles  120 ,  130  are biased toward the closed position. Thus, when moving the handles  120 ,  130  from the open position to the closed position, the handles may snap into the closed position after passing the over-center position. When opening or unfolding the handles  120 ,  130 , the handles can freely rotate toward the open position after passing the over-center position. 
     When handles  120  and  130  are rotated to the open position, interlocking features  126  and  136 , as shown in  FIG. 4 , may releasably couple the two handles in the open position.  FIG. 4  shows an embodiment in which handles  120  and  130  are identical. The Figure shows the two handles unassembled from blade  110 , showing the back side of both handles. To assemble the handles to blade  110 , one handle is rotated 180 degrees relative to the other. When handles  120  and  130  are coupled to blade  110  and are in the open position, the back sides of the two handles face each other and interlocking features  126  and  136  may snap together. Each of interlocking features  126  and  136  may comprise a protruding portion and a recessed portion. For example, interlocking feature  126  may have a protruding portion  126 A that is received by a recessed portion  136 B, and may have a recessed portion  126 B that receives protruding portion  136 A. 
     More detail of the interlocking features  126  and  136  is provided in  FIGS. 5A-5C , which show a top view and a cross sectional view of chisel  100  in the open position.  FIG. 5B  shows releasable coupling of the two handles in  FIG. 5A  from the perspective of line  5 B- 5 B in  FIG. 5A . Each interlocking feature  126 ,  136  may comprise a resilient finger  126 C and  136 C, respectively, with a bulge formed on the end thereof. The finger  126 C or  136 C of each of interlocking features  126  and  136  may be sufficiently resilient to be capable of being deflected away from the other interlocking feature, towards a recessed portion  126 D or  136 D, respectively, behind the finger  126 C or  136 C. 
     As handles  120  and  130  are rotated to the open position and interlocking features  126  and  136  engage each other, the bulge portion of each finger  126 C and  136 C may slide against the other interlocking feature. After the bulge portion of finger  126 C slides past end surface  136 E, it snaps into a position that opposes reverse motion of finger  126 C relative to the other interlocking feature  136 . After the bulge portion of finger  136 C slides past end surface  126 E, it snaps into a position that opposes reverse motion of finger  136 C relative to the other interlocking feature  126 . When interlocking features  126  and  136  are snapped together, the bulges of finger  126 C and  136 C tend to keep handles  120  and  130  in the open, unfolded position. 
     When handles  120  and  130  are pulled from the open position to rotate them toward the closed position, a sufficient pulling force may deflect the fingers  126 C and  136 C of interlocking features  126  and  136 , respectively, so that they release the coupling between the two handles  120  and  130 . For example, as shown in  FIGS. 5B and 5C , handle  120  may be pulled in an upward direction and handle  130  may be pulled in a downward direction to rotate them toward the closed position. The pulling force may be transferred to interlocking features  126  and  136 . The force may deflect the resilient finger  126 C towards the recessed portion  126 D behind the finger  126 C, and may deflect the resilient finger  136 C towards the recessed portion  136 D behind the finger  136 C. Deflecting finger  126 C and  136 C toward recess  126 D and  136 D, respectively, moves the bulge of each finger away from their snapped positions. A sufficient deflection of finger  126 C and  136 C and of their bulges may allow the two fingers to slide past each other toward the closed position. The bulge of finger  126 C, for example, may be sufficiently deflected to allow finger  126 C to slide upwards, away from end surface  136 E, while the bulge of finger  136 C may be sufficiently deflected to allow finger  136 C to slide downwards, away from end surface  126 E. 
     In some embodiments, handles  120  and  130  may not be identical. For example, only one of fingers  126 C and  136 C may have a bulge formed on the end thereof, or the two fingers  126 C and  136 C may each have a bulge formed thereon that has a different shape from the bulge of the other finger. 
     Although embodiments in the figures show a chisel blade, other embodiments of the invention may include a gouge blade, a file blade, a knife blade, or any other type of blade. 
     While the principles of the invention have been made clear in the illustrative embodiments set forth above, it will be apparent to those skilled in the art that various modifications may be made to the structure, arrangement, proportion, elements, materials, and components used in the practice of the invention. 
     It will thus be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodiments have been shown and described for the purpose of illustrating the functional and structural principles of this invention and are subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.