Patent Document

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.  FIGS. 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  100   a  that intersects an angled segment  104   a.    
     In  FIG. 6B , the relieved region  99  has a leading angled segment  100   b  joined to a radiused segment  102   a , which is in turn joined to an angled segment  104   b . In some implementations, the segment  104   b  is not present. 
     In  FIG. 6C , the relieved region  99  is defined by an angled segment  100   b  which is joined to a radiused segment  102   b . As indicated, the radiused segment  102   b  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, Oreg. 
     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.

Technology Category: 7