BACKGROUND
This application relates to wood planing, and specifically to a cutter head assembly for a knife planer.
Wood planing machinery such as knife planers are used to finish wood. In some applications, lumber boards are subjected to cutter head finishing operations on each of their four sides in a knife planer to achieve a smooth finish.
Cutter heads have multiple, spaced apart, projecting blades and are rotated at high speed in contact with a wood workpiece to finish it. Over time, the cutter head blades become dull and require resharpening (called “pointing”). As blades wear, they can be adjusted to project from a body of the cutter head by a desired distance. Ultimately, blades wear to an extent where they can no longer be used and must be replaced by new blades.
A component called a gib, which is used in connection with one or more gib screws, is used to secure each blade in its respective slot. The gib and gib screw arrangement allows the blade to be installed and removed, as well as to be adjusted. Because each current gib and gib screw arrangements require substantial angular space around the cutter head body, the number of blades per cutter head of a given diameter is limited.
SUMMARY
Described below are representative implementations of a cutter head assembly that addresses shortcomings of the prior art.
According to one implementation, a cutter head assembly for a planing apparatus comprises a rotatable cutter head body, a first slot and a gib assembly. The cutter head body has a first end, an opposite second end and an outer periphery extending between the first end and the second end in a longitudinal direction. There is at least a first slot formed in the outer periphery and extending generally longitudinally. Viewed in section, the first slot has at least one profiled side and an opposite knife blade side. The gib assembly is positionable to retain a planing knife blade in the first slot at a desired position adjacent the knife blade side. The gib assembly comprises an elongate gib and at least one gib screw. Viewed in section, the gib has a shaped leading side and an opposite trailing side. The gib screw is rotatable to move the trailing side of the gib toward the knife blade side of the slot by contact between the shaped leading side of the gib and the profiled side of the first slot, thereby clamping the planing knife blade between the trailing side of the gib and the knife blade side of the slot.
The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a cutter head assembly showing one of the knife blade and gib assemblies partially exploded.
FIG. 2 is a partial end view of the cutter head showing multiple spaced apart slots and a gib assembly and knife blade installed in one of the slots.
FIG. 3 is a partial end view of the cutter head showing the configuration of a single slot in detail.
FIG. 4. is a sectioned elevation view of the gib of FIG. 1.
FIGS. 5A and 5B are side elevation and top plan views of the gib screw of FIG. 1.
FIGS. 6A, 6B and 6C are elevation views of representative geometries of an outer side of the gib.
FIG. 7 is an end view of a large cutter head assembly having the same slot and gib assembly configuration as shown in FIG. 1.
FIG. 8 is an end view of a small cutter head assembly having the same slot and gib assembly configuration as shown in FIG. 1.
DETAILED DESCRIPTION
Referring to FIG. 1, a cutter head assembly 10 has a cutter head body 12 rotatable about an axis extending through its end surfaces 14, 16. The cutter head body 12 has an outer periphery or side surface 18 extending between the end surfaces 14 and 16. As shown, at least one slot 20 is formed in the cutter head body 12 and extends generally longitudinally between the end surfaces 14, 16. In the implementation of FIG. 1, there are 18 evenly spaced slots 20. Each slot 20 is configured to receive a knife blade 22 that is held in place within the slot 20 by a gib assembly 30.
For purposes of illustration, the uppermost slot 20 as depicted in FIG. 1 is shown with the knife blade 22 and each of two gib assemblies 30 partially removed to reveal other components. As shown, each gib assembly 30 includes a gib 32, at least one gib screw 34 configured to be received in a gib screw aperture 36 extending through the gib 32. In the example of FIG. 1, each gib 32 has two such gib screws 34 and respective gib screw apertures 36.
Referring to FIG. 2, which is a section of a portion of the cutter head assembly 10, the relative positions of the knife blade 22, the gib 32 and the gib screw 34 as installed in one of the slots 20 are shown. A projecting tip of the knife blade 22 extends beyond the outer periphery 18 of the cutter head body 12 and defines a cutting circle C. The gib screw 34 is tightened or loosened to cause the gib 32 to move within the slot and effect a clamping action on the knife blade 22. In the illustrated implementation, the gib 32 urges the blade 22 against one side of the slot 20 as is described below in greater detail.
Portions of the gib 32 and the slot 20 have complementary geometry, as is best described in connection with FIGS. 2-4. Referring to FIG. 4, which shows a section of the gib 32, the gib 32 has a shaped leading side 38 (also called a forward side) and an opposite trailing side 40 (also called a rearward side). In the illustrated implementation, the shaped leading side 38 includes a first angled segment 42 and a second angled segment 44 that is spaced away from the first angled segment 42 and one or more intermediate surface(s) 46 separating the first angled segment and the second angled segment. There are two such intermediate surfaces 46 in the implementation shown in FIG. 4. There is a bottom side 48 that connects the leading side 38 and trailing side 40. The trailing side 40 includes a blade mounting surface 50 by which contact between the gib 32 and the knife blade 22 is made.
Optionally, the trailing side 40 may include a recessed surface 54 as shown that is dimensioned to remain spaced apart from the knife blade (see FIG. 2). A minimum knife indicator 52 can be defined at an interface between the blade contacting surface 50 and the recessed surface 54. The minimum knife indicator 52, if present, provides a visual indication to the operator of whether the knife has been worn beyond it usable extent. In addition, by providing a blade contacting surface 50 that is sized and shaped as shown, a clamping force can be achieved as desired, without undesirable point loading. A top side 56 of the gib 32 extends between the leading side 38 and the trailing side 40. In the implementation shown in FIG. 4, there is forward top side region 58 and a rearward top side region 60.
Referring again to FIG. 2, and particularly to the labeled empty slot, the illustrated section of slot 20 can be described as having a rearward side 70 (also called the knife blade side), a bottom side 72 and a forward side 76 (also called the profiled side). The bottom side 72 is joined to the rearward side 70 at a radiused corner 74. Similarly, the bottom side 72 is joined to the forward side 76 at a radiused corner 78. The profiled side 76 has at least a first angled segment 80 and a second angled segment 82. As illustrated, the second angled segment 82 is spaced apart from the first angled segment 80 by at least one intermediate surface 84. In the specific implementation shown, there is one intermediate surface 84 extending approximately parallel to the rearward side 70 and another intermediate surface 84 angled forwardly or in a diverging direction.
As shown in FIGS. 1-4, and with specific reference to FIG. 2, the gib 32 and the slot 20 have respective angled segments configured for contact with each other and to effect a clamping action against the blade 22. That is, the first angled segment 42 of the gib is configured to complement the first angled segment 80 of the slot. Similarly, the second angled segment 44 of the gib 32 is configured to complement the second angled segment 82 of the slot 20. The gib screw 34 is dimensioned to extend through the gib screw aperture 36 and into direct contact with the bottom side 72 of the slot, or, as illustrated, an optional insert 24 positioned to protect the bottom side 72. As the gib screw 34 is threaded or unthreaded relative to the gib 32, the gib 32 moves along the slot axis S and also moves laterally along the axis L due to the wedging action of the angled segments in contact with each other. The first angled segments can be described as defining a first convergent angle relative to the slot axis S in the direction from the bottom side of the slot outward. Similarly, the second angled segments 44, 82 can be described as defining a second radially converging angle relative to the slot axis S.
In the illustrated implementation, the first angled segment 42 and the first angled segment 80 are configured to have approximately the same angular dimension, but in alternative implementations, these angles could differ. Similarly, the second angled segment 44 and the second angled segment 82 have approximately the same angular dimension in the illustrated implementation, but these angles could differ. Further, the first angled segments 42, 80 may have angles that differ from the second angled segments 44, 82. In one implementation, the angled segments 42, 44, 80 and 82 are dimensioned to have angles of approximately 5-30°. In another implementation, the angled segments 42, 44, 80 and 82 are dimensioned to have angles of approximately 15-25°. In yet another specific implementation, the angled surfaces 42, 44, 80 and 82 are dimensioned to have angles of approximately 20°.
As shown in FIGS. 5A and 5B, the gib screw 34 has a head 92, a shaft 94 and an end 96. The head 92 may have any suitable configuration. In the illustrated implementation, the head 92 is configured to have a socket head configuration, such as to receive a Torx® bit (another type of a bit, such as an Allen key, could also be used).
Over time, the gib 32 may wear. In particular, the gib 32 can be shaped to focus wear to occur along its top side 56 and in a relieved region 99 by directing shavings away from the cutterhead. The wear that occurs on the gib 32 tends to reduce wear on the adjacent section of the cutter head body 12, which is advantageous because the gib 32 can be replaced relatively easily and inexpensively. FIG. 6A, 6B and 6C illustrate alternative configurations for the relieved region 99 on the top side 56 of the gib 32.
In FIG. 6A, a section of the profile of the relieved region 99 has an angled leading segment 100a that intersects an angled segment 104a.
In FIG. 6B, the relieved region 99 has a leading angled segment 100b joined to a radiused segment 102a, which is in turn joined to an angled segment 104b. In some implementations, the segment 104b is not present.
In FIG. 6C, the relieved region 99 is defined by an angled segment 100b which is joined to a radiused segment 102b. As indicated, the radiused segment 102b is slightly upturned by an angle d at the trailing side of the gib 32. A specification implementation, the angle d is approximately 11°, but could be in the range from about 0° to about 30°.
The described approaches for positioning and retaining a cutting blade can be implemented in any suitable configuration. For example, FIG. 7 shows a large cutter head 110 having 36 slots and blades. In contrast, FIG. 8 shows a small cutter head 120 having 18 slots and blades, similar to FIG. 1. Of course, it would be possible to implement the same approach in a cutter head having more slots or fewer slots than the cutter heads 110, 120.
The cutter head body 12 can be made of any suitable material, such as a high carbon steel. The gib 32 and gib screw 34 are also formed of suitable materials such as high carbon steel and/or tool steel. The knife blade 22 can be any commercially available knife blade, such as those sold by Global Tooling and Supply of Eugene, Oregon.
One suitable seal 37 is the Parker Model 2-010N70 seal. The insert 24 can be made of any suitable material, such as metal strapping material.
In the illustrated implementations, the gib and slot are configured to have two sets of angled surfaces. In other implementations, it would be possible to achieve the same benefits using a fewer or greater number of angled surfaces.
In view of the many possible embodiments to which the disclosed principles may be applied, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting the scope of protection. Rather, the scope of protection is defined by the following claims. We therefore claim all that comes within the scope and spirit of these claims.
Patent Application
20160008999
