Technical Field
The present disclosure relates generally to bits for cutting tools, and more particularly to a non-rotating bit assembly for a tool holder of a milling-type machine such as a cold planer or rotary mixer.
Background
Asphalt-surfaced roadways facilitate vehicular travel. Depending upon usage density, base conditions, temperature variation, moisture variation, and/or physical age, the surface of the roadways can eventually become misshapen, non-planar, unable to support wheel loads, or otherwise unsuitable for vehicular traffic. To rehabilitate the roadways for continued vehicular use, worn road surface (e.g., asphalt or concrete) is removed in preparation for resurfacing.
Cold planers, sometimes also called road mills or scarifiers, are machines that typically include a frame supported by tracked or wheeled drive units. The frame is configured to provide a mount for an engine, an operator's station, and a milling drum. The milling drum, fitted with cutting tools, is turned through a suitable interface by the engine to break up the surface of the roadway. In a typical configuration, multiple cutting tools are provided on an external surface of the milling drum. The cutting bits are conventionally mounted to the tool holders such that the cutting bits are free to rotate during use.
However, rotation of the cutting bit has several notable disadvantages. For certain cutting bits, such as those having polycrystalline diamond (PCD) tips, rotation of the cutting bit allows all side of the bit to wear, which reduces the strength of the bit. Further, rotation of cutting tools can lead to wear and consequently reduced service of the tool holder. For example, rotation of the cutting bit may result in wear on the face and the internal bore of the tool holder (that is contacted by the cutting bit) such that the tool holder is less effective at or incapable of holding cutting bits.
U.S. Pat. No. 8,646,848 to Hall et al. (hereinafter “the '848 patent”) discloses a pick assembly including a pick shank configured to be press fit directly within a bore of a block. The pick shank includes an inside and outside surface, and the pick includes a pick head opposite the shank. The shank comprises at least one longitudinal recess extending towards the pick head along the shank from a distal end of the shank. The recess allows the shank to resiliently collapse upon insertion into the bore while maintaining a press fit between the bore and the shank. The shank additionally has tapered regions that engage in a press fit with a corresponding tapered region of the bore of the block.
The '848 patent requires a block having a non-standard, tapered bore. As such, the pick shank cannot be used as a universal replacement without first retrofitting the cutting machine with the required tapered block.
The cutting bit assembly of the present disclosure solves one or more of the problems set forth above and/or other problems in the art.
Summary
According to one aspect of the present disclosure, a cutting bit assembly for attachment to a tool holder of a milling-type machine includes a cutting tip, a generally cylindrical shank extending from the cutting tip and including a rotation-limiting surface, and a spring clip surrounding a body of the shank. The spring includes a protrusion configured to interact with the rotation-limiting surface of the shank to limit rotation of the shank relative to the spring clip. The spring clip includes a contracted configuration and an expanded configuration, and in both the contracted configuration and the expanded configuration the protrusion interacts with the rotation-limiting surface.
In another aspect, a method for installing a cutting bit assembly into a tool holder of a milling-type machine includes inserting a shank of the cutting bit assembly into a mounting bore of the tool holder with a spring clip of the cutting bit assembly in a contracted configuration, and releasing the spring clip from the contracted configuration so that the spring clip exerts a radially outward force against the mounting bore of the tool holder, thereby causing the spring clip to be rotationally locked to the mounting bore. The spring clip includes a protrusion configured to interact with a rotation-limiting surface of the shank to limit rotation of the shank relative to the spring clip and to the tool holder
In yet another aspect, a cutting bit assembly for attachment to a tool holder of a milling-type machine includes a cutting tip, a generally cylindrical shank extending from the cutting tip and including a rotation-limiting surface, a pin, and a spring clip surrounding a body of the shank. The spring clip includes a protrusion configured to interact with the pin to limit rotation of the shank relative to the spring clip. The pin is disposed between the rotation-limiting surface of the shank and the protrusion. The spring clip includes a contracted configuration and an expanded configuration, and in both the contracted configuration and the expanded configuration the protrusion interacts with the pin.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and together with the description, serve to explain the principles of the disclosed embodiments.
FIG. 1 is an exploded view of a cutting tool of a cold planer, according to aspects of the present disclosure.
FIG. 2 is a perspective view of a cutting bit, according to aspects of the present disclosure.
FIG. 3 is a perspective view of a cutting bit assembly, including the cutting bit of FIG. 2, according to aspects of the present disclosure.
FIG. 4 is a perspective view of a spring clip of the cutting bit assembly of FIG. 3.
FIG. 5 is a cross-section view of the spring clip of FIG. 4, taken along line 5-5.
FIG. 6 is a cross-sectional view of the cutting bit assembly of FIG. 3, taken along line 6-6.
FIG. 7 is a perspective view of an alternative cutting bit, according to aspects of the present disclosure.
FIG. 8 is a side elevational view of a cutting bit assembly, including the cutting bit of FIG. 7, according to aspects of the present disclosure.
FIG. 9A is a perspective view of a spring clip of the cutting bit assembly of FIG. 8.
FIG. 9B is a perspective view of an alternative spring clip, according to aspects of the present disclosure.
FIG. 10 is a cross-sectional view of the cutting bit assembly of FIG. 8, taken along line 10-10.
FIG. 11 is a perspective view of yet another cutting bit, according to aspects of the present disclosure.
FIG. 12 is a side view of a cutting bit assembly, including the cutting bit of FIG. 11, according to aspects of the present disclosure.
FIG. 13 is a cross-sectional view of the cutting bit assembly of FIG. 12, taken along line 13-13, according to aspects of the present disclosure.
FIG. 14 is a cross-sectional view of the cutting bit assembly of FIG. 12, taken along line 14-14.
FIG. 15 is a cross-sectional view of yet another cutting bit assembly according to aspects of the present disclosure.
FIG. 16 is a cross-sectional view of yet another cutting bit assembly according to aspects of the present disclosure.
FIG. 17 provides a flowchart depicting an exemplary method for installing a cutting bit assembly into a tool holder, according to aspects of the present disclosure.
FIG. 18 provides a flowchart depicting an exemplary method for removing a cutting bit assembly from a tool holder, according to aspects of the present disclosure.
DETAILED DESCRIPTION
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed. As used herein, the terms “comprises,” “comprising,” “has,” “having,” “includes,” “including,” “limited,” or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements need not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus. In this disclosure, unless stated otherwise, relative terms, such as, for example, “about,” “substantially,” and “approximately” are used to indicate a possible variation of +10% in the stated value. Throughout the accompanying drawings, like reference numerals refer to like components.
Referring to FIG. 1, a cold planer or other milling-type of machine (e.g., rotary
mixer) includes a milling drum 100 which is a generally cylindrical, rotating structure for cutting and grinding a substrate such as a roadway asphalt. Milling drum 100 has an outer surface 102 on which a plurality of tool assemblies 104 are arranged. Each tool assembly 104 includes a tool mounting block 108, a tool holder 110, and a cutting bit assembly 200. Tool assemblies 104 may be arranged in such a way that rotation of milling drum 100 causes the cutting bit assembly 200 of each tool assembly 104 to fragment and remove material from the roadway surface and channel it to a collection device (not shown). While only a single tool assembly 104 is shown in FIG. 1, milling drum 100 may have several tool assemblies 104 arranged in a series of rows, rings, spirals, etc. on outer surface 102.
For each tool assembly 104, tool mounting block 108 may be fixed to the milling drum outer surface 102, for example, by welding, and is configured to removably receive tool holder 110 in a mounting bore 114 of a mounting portion 116. Tool holder 110 includes an end face 120 and a mounting bore 122 configured to removably receive cutting bit assembly 200. Mounting bore 122 may have an inner diameter of, for example, 20 millimeters (mm). With continued reference to FIG. 1 and further reference to FIGS. 2 and 3, cutting bit assembly 200 includes a cutting tip 210 and a shank 220 extending from cutting tip 210. Cutting tip 210 may be substantially conical and may have a substantially pointed distal end 212 which tapers radially outwardly to form a flange 214 from which shank 220 extends. Flange 214 may have a diameter of about 22-28 mm, and in some aspects about 45 mm. In some aspects, distal end 212 includes a polycrystalline diamond tip for milling the substrate, though other abrasive materials may alternatively be used.
With continued reference to FIG. 2, shank 220 includes a body 222, a shoulder 228 between body 222 and flange 214, and a proximal end 224. Body 222 of shank 220 is generally cylindrical apart from the presence of rotation-limiting surface 230, described below. Shoulder 228 is generally cylindrical and extends 360° around body 222. Shoulder 228 may have an outer diameter of slightly less than the diameter of mounting bore 122 of tool holder 110 so that shoulder 228 has a clearance fit with mounting bore 122. For example, shoulder 228 may have an outer diameter of slightly less than 20 mm. Shoulder 228 may extend longitudinally from flange 214 about 3-12 mm, and in some aspects about 5 mm. Proximal end 224 may be generally cylindrical with the exception of notch 226, as described below. Proximal end 224 may have an outer diameter of slightly less than the diameter of mounting bore 122 of tool holder 110 so that proximal end 224 has a clearance fit with mounting bore 122. For example, proximal end 224 may have an outer diameter of slightly less than 20 mm. Proximal end 224 may have a length of about 5-15 mm, and in some aspects about 10 mm.
Body 222 of shank 220 has an outer diameter less than that of shoulder 228 and proximal end 224, such as a diameter of about 10-36 mm, and in some aspects about 14 mm. Body 222 of shank 220 may have a length, i.e. the distance between shoulder 228 and proximal end 224, of about 25-50 mm, and in some aspects about 35 mm. Shank 220, including body 222, proximal end 224, and shoulder 228, may be made from a strong, rigid material such as a heat-treatable steel (e.g., AISI 1040 steel).
As shown in FIGS. 1 and 3, body 222 is at least partially surrounded by a spring clip 260 which can be resiliently deflected between a contracted (or stressed) configuration and an expanded (or unstressed) configuration. Spring clip 260 may be made from a material such as spring steel that imparts elasticity to spring clip 260.
The elasticity of spring clip 260 is such that spring clip 260 is in the expanded configuration in the absence of an external constraint. In the expanded configuration, an outer diameter of spring clip 260 is larger than an inner diameter of mounting bore 122 of tool holder 110. In the contracted configuration, the outer diameter of spring clip 260 is less than that of the expanded configuration to allow spring clip 260 to be inserted into mounting bore 122 of tool holder 110. The outer diameter of spring clip 260 in the contracted configuration is slightly greater than the inner diameter of mounting bore 122, creating a slight press fit between mounting bore 122 and spring clip 260 in the contracted configuration. For example, the outer diameter of spring clip 260, in the contracted configuration, may be slightly greater than 20 mm. In some aspects, the outer surface of spring clip 260 may have a surface treatment to increase friction with mounting bore 122.
Referring now to FIG. 3, cutting bit assembly 200 further includes a washer 290 that surrounds spring clip 260 and holds spring clip 260 in the contracted configuration on body 222 of shank 220. Washer 290 is generally flat and annular in shape, having an outer diameter and a bore concentric with the outer diameter. Washer 290 may have an outer diameter approximately equal to the outer diameter of flange 214. Washer 290 may have a thickness of about 3-8 mm, and in some aspects about 5 mm. Bore of washer 290 has a diameter corresponding to the outer diameter of spring clip 260 in the contracted configuration. Proximal edge 292 and distal edge (obstructed from view in FIG. 3) of the bore of washer 290 may be beveled to assist in installation, removal, and/or reuse of bit assembly 200, as described below. Similarly, proximal edge 296 and distal edge 298 of the outer diameter of washer 290 may be beveled to assist in installation, removal, and/or reuse of bit assembly 200, as described below.
The bias of spring clip 260 acts against the bore of washer 290, which results in a friction fit that maintains an axial position of washer 290 on spring clip 260. When cutting bit assembly 200 is installed into mounting bore 122 of tool holder 110 (see FIG. 1), washer 290 is pushed onto shoulder 228 and into abutment with flange 214 (to the position shown in FIGS. 12 and 14). The bevel on distal edge of the bore of the washer 290 may guide washer 290 onto shoulder 228.
With reference to FIGS. 2 and 3, proximal end 224 of shank 220 may retain spring clip 260 axially on body 222 of shank 220. In the expanded configuration, spring clip 260 may have an inner diameter larger than or equal to an outer diameter of proximal end 224, so that spring clip 260 may be slid over proximal end 224 to install spring clip 260 onto body 222 of shank 220. Washer 290 may be installed after spring clip 260 has been slid onto body 222 of shank 200. Washer 290 forces spring clip 260 into the contracted configuration, in which the inner diameter of spring clip 260 is less than the outer diameter of proximal end 224 of shank 220. As such, spring clip 260 cannot slide over proximal end 224 when in the contracted configuration. Similarly, the inner diameter of spring clip 260, in the contracted configuration, is less than the outer diameter of the shoulder 228, so the spring clip 260 cannot slide over shoulder 228 when in the contracted configuration. Thus, spring clip 260 is retained between shoulder 228 and proximal end 224.
With continued reference to FIG. 2, shank 220 includes a rotation-limiting surface 230 configured to interact with spring clip 260 to limit rotation between shank 220 and spring clip 260. In the aspect shown in FIG. 2, rotation-limiting surface 230 includes a first planar surface 232 and a second planar surface 234. First planar surface 232 and second planar surface 234 may be recessed into body 222 of shank 220, and may be adjacent one another and arranged at an angle a (see FIG. 6) relative to one another. Angle a may be about 135-145°, and in some aspects about 140°. In some aspects (not shown), first and second planar surfaces 232, 234 may be spaced apart from one another Each of first and second planar surfaces 232, 234 may be substantially rectangular, and have a length (along longitudinal axis of shank 220) of about 17-37 mm, and in some aspects about 27 mm, and a width (transverse to longitudinal axis of shank 220) of about 5-10 mm, and in some aspects about 7 mm. In other aspects, first and second planar surfaces 232, 234 may be shapes other than rectangular, e.g. pill-shaped, oval, trapezoidal, hexagonal, or the like.
In some aspects, each of first and second planar surfaces 232, 234 may be spaced apart from shoulder 228 by about 2-8 mm, and in some aspects about 5 mm. In some aspects, each of first and second planar surfaces 232, 234 may be spaced apart from proximal end 224 by about 5-16 mm, and in some aspects about 12 mm.
Referring now to FIGS. 3-6, spring clip 260 extends along a longitudinal axis 262 and is generally tubular in shape (apart from protrusions 270, 280). Spring clip 260 includes a slit 264 extending from a proximal end to a distal end to allow spring clip 260 to transition between the contracted configuration and the expanded configuration. In particular, slit 264 is narrower in the contracted configuration of spring clip 260 than in the expanded configuration of spring clip 260. In some aspects, a distal edge 266 of spring clip 260 may be beveled. In some aspects, the wall thickness of spring clip 260 may be between about 1.50 mm and 1.75 mm.
Spring clip 260 includes one or more internal protrusions extending radially inward towards longitudinal axis 262 from the inner diameter. In the aspect shown in FIGS. 3-6, spring clip 260 includes two protrusions 270 and 280 spaced apart along longitudinal axis 262. Protrusions 270, 280 may be formed by a press operation such that protrusions 270, 280 are indented into the sidewall of spring clip 260. In other aspects, protrusions 270, 280 may include material added to inner sidewall of the spring clip 260. Protrusion 270 includes a third planar surface 272 and a fourth planar surface 274. Third planar surface 272 and fourth planar surface 274 may be arranged at an angle ß relative to one another (see FIG. 5). Angle ß may be about 136-156°, and in some aspects about 146°. Each of third and fourth planar surfaces 272, 274 may be substantially rectangular, and have a length (along longitudinal axis of shank 220) of about 7-17 mm, and in some aspects about 11 mm, and a width (transverse to longitudinal axis of shank 220) of about 4-8 mm, and in some aspects about 6 mm. The overall length of the protrusions, including both third and fourth planar surfaces 272, 274 of protrusion 270 and analogous planar surfaces of protrusion 280, may be about 8-35 mm, and in some aspects about 27 mm. In other aspects, third and fourth planar surfaces 272, 274 may be shapes other than rectangular, e.g. pill-shaped, oval, trapezoidal, hexagonal, or the like.
As shown in FIG. 6, protrusion 270 of spring clip 260 interacts with rotation-limiting surface 230 of shank 220 to limit rotation of shank 220 relative to spring clip 260 in both the contracted and expanded configurations of spring clip 260. In particular, third planar surface 272 of spring clip 260 is configured to engage first planar surface 232 of rotation limiting surface 230 of shank 220 to limit rotation of shank 220 in a clockwise direction 50 within spring clip 260. Similarly, fourth planar surface 274 of spring clip 260 is configured to engage second planar surface 234 of rotation limiting surface 230 of shank 220 to limit rotation of shank 220 in a counter-clockwise direction 52 within spring clip 260.
In some aspects, angle ß of protrusion 270 of spring clip 260 is greater than angle a of rotation-limiting surface 230 of shank 220. As such, an angular gap 0 is present between first planar surface 232 and third planar surface 272, and/or present between second planar surface 234 and fourth planar surface 274. Angular gap 0 allows limited rotation of shank 220 within spring clip 260. Shank 220 may be rotated in clockwise direction 50 within spring clip 260 until first planar surface 232 of rotation-limiting surface 230 engages third planar surface 272 of protrusion 270. Similarly, shank 220 may be rotated in counter-clockwise direction 52 within spring clip 260 until second planar surface 234 of rotation-limiting surface 230 engages fourth planar surface 274 of protrusion 270.
Angle ß of protrusion 270 of spring clip 260 may be greater when spring clip 260 is in the expanded configuration compared to the retracted configuration, due to the overall expansion of spring clip 260. Thus, shank 220 may have less rotational freedom relative to spring clip 260 when spring clip 260 is in the contracted configuration compared to when spring clip 260 is in expanded configuration.
Protrusion 280 may be substantially identical to protrusion 270, including a third planar surface and a fourth planar surface analogous to third planar surface 272 and fourth planar surface 274, respectively. Protrusions 270 and 280 may be separated by a rib 275 that provides rigidity to and resists deformation of spring clip 260. In some aspects, spring clip 260 may include only a single protrusion 270, with rib 275 being absent.
In order to accommodate protrusions 270 and 280, proximal end 224 of shank 220 (see FIG. 2) includes a notch 226 that provide clearance for protrusions 270, 280 to slide over proximal end 224 onto body 222 of shank 220 when spring clip 260 is being installed on shank 220. Notch 226 is shaped to accommodate protrusions 270, 280. Thus, notch 226 may include a pair of planar surfaces respectively allowing third planar surface 272 and fourth planar surface 274 of protrusion 270 (along with analogous surfaces of protrusion 280) to slide over proximal end 224.
FIGS. 7, 8, 9A, and 10 illustrate another aspect of cutting bit assembly 300 according to the present disclosure, with corresponding components of cutting bit assembly 200 shown by 100 added to the reference number. Components not specifically described in relation to FIGS. 7-10 may be presumed to be substantially similar to corresponding components of the aspect of FIGS. 2-6. Cutting tip 310 of the aspect of FIGS. 7, 8, and 10 may be substantially identical to cutting tip 210 of FIGS. 2-6. As shown in FIG. 7, rotation-limiting surface 330 of body 322 of shank 320 includes a groove 336 recessed into body 322. Groove 336 may be about 17-37 mm long, and in some aspects about 27 mm long, and about 8-15 mm wide, and in some aspects about 12 mm wide. Groove 336 may be recessed into body 322 of shank 320 by about 1-5 mm relative to the outer diameter of body 322, and in some aspects by about 2 mm relative to the outer diameter of body 322. Groove 336 may be spaced apart from shoulder 328 by about 2-8 mm, and in some aspects about 5 mm. Groove 336 may be spaced apart from proximal end 324 by about 5-16 mm, and in some aspects about 12 mm.
As shown in FIGS. 8, 9A, and 10, protrusion 370 of spring clip 360 includes tabs 376 extending radially inward toward longitudinal axis 362. The illustrated aspect includes two tabs 376, though any number of tabs (such as one, two, three, four, etc.) may be used. Tabs 376 may be formed, for example, by a punch operation to bend tabs 376 inward. Tabs 376 may be generally symmetric, as illustrated, but need not be so. Tabs 376 may have a length (in a direction parallel to longitudinal axis of shank 320) of about 4-10 mm, and in some aspects of about 7 mm. Tabs 376 may extend inward from the inner sidewall of spring clip 360 by about 1-4 mm, and in some aspects by about 2 mm. Protrusion 380 may be substantially identical to protrusion 370. In some embodiments, spring clip 360 may include only a single protrusion 370.
As shown in FIG. 10, tabs 376 interact with rotation-limiting surface 330 in both the contracted and expanded configuration of spring clip 360 to limit rotation of shank 320 within spring clip 360. In particular, tabs 376 extend into groove 336 of shank 320 so that rotation of shank 320 causes tabs to engage sidewalls 338 of groove 336. In some aspects, as shown in FIG. 10, there is negligible clearance between tabs 376 and sidewalls 338, so little or no rotation of shank 320 relative to spring clip 360 is permitted. In other aspects, there may be clearance between tabs 376 and sidewalls 338 to allow a limited, predetermined amount of rotation of shank 320 relative to spring clip 360.
As shown in FIGS. 7 and 8, notch 326 in proximal end 324 of shank 320 may include a single planar surface to allow tabs 376 to clear proximal end 324 as spring clip 360 is installed onto shank 320.
As shown in FIG. 8, washer 390 retains spring clip 360 in the contracted configuration in same manner as described herein in connection with the aspect of FIGS. 2-6.
FIG. 9B illustrates another aspect of spring clip 360. Spring clip 360 of FIG. 9B includes a single protrusion, namely protrusion 370, which may extend substantially the entire length of spring clip 360. Protrusion 370 includes a tab 377 extending radially toward longitudinal axis 362. Tab 377 may be formed by rolling or bending one of the edges of spring clip 360 on either side of slit 364. Tab 377 fits into groove 336 of shank 320 (see FIG. 10) in substantially the same manner as tabs 376 of the aspect of FIG. 9A, and tab 377 engages sidewalls 338 of groove 336 to limit or prevent rotation of shank 320 relative to spring clip 360. Because the aspect of FIG. 9B includes only a single tab 377, groove 336 of shank 320 may be narrower than shown in FIG. 10 to limit slop between tab 377 and sidewalls 338 of groove 336. Further, groove 336 may extend substantially the entire length of body 322 of shank 320 in order to accommodate tab 377, which extends substantially the entire length of spring clip 360. That is, groove 336 may extend substantially the entire distance between proximal end 324 and shoulder 328. In other aspects (not shown), both edges of spring clip on either side of slit 364 may be formed into a tab, and groove 336 of shank 320 may be of a width suitable to accommodate two tabs.
FIGS. 11-14 illustrate another aspect of cutting bit assembly 400 according to the present disclosure, with corresponding components of cutting bit assembly 200 shown by 200 added to the reference number. Components not specifically described in relation to FIGS. 11-14 may be presumed to be substantially similar to corresponding components of the aspect of FIGS. 2-6. Cutting tip 410 of the aspect of FIGS. 11-14 may be substantially identical to cutting tip 210 of FIGS. 2-6. As shown in FIGS. 11 and 13, rotation-limiting surface 430 may include a single planar surface 440 recessed into body 422. Planar surface 440 may be about 17-37 mm long, and in some aspects about 27 mm long, and about 13-16 mm wide, and in some aspects about 15 mm wide. Planar surface 440 may be recessed into body 422 of shank 420 by about 2-6 mm relative to the outer diameter of body 422, and in some aspects by about 4 mm relative to the outer diameter of body 422. Planar surface 440 may be spaced apart from shoulder 428 by about 2-8 mm, and in some aspects about 5 mm. Planar surface 440 may be spaced apart from proximal end 424 by about 5-16 mm, and in some aspects about 12 mm. Planar surface 440 may extend partially around circumference of body 422 of shank 420, such as about 99-139° around circumference of body 422, and in some aspects about 119° around circumference of body 422.
As shown in FIGS. 13-14, cutting bit assembly 400 further includes a pin 450 constrained between spring clip 460 and rotation-limiting surface 430 of shank 420. Pin 450 is generally cylindrical and is aligned parallel to longitudinal axis of spring clip 460. Pin 450 may have a length of about 15-35 mm, or in some aspects about 25 mm, and a diameter of about 1-5 mm, or in some aspects about 3 mm. Spring clip 460 may include an inspection aperture 468 that allows viewing of pin 450 through spring clip 460 so that an operator/installer can verify that pin 450 is properly seated between spring clip 460 and planar surface 440 of shank 420 prior to and/or during installation of cutting bit assembly 400 into milling drum 100.
As shown in FIGS. 12 to 14, protrusions 470, 480 of spring clip 460 retain pin 450 in position on planar surface 440. Protrusions 470, 480 interact with rotation-limiting surface 440, via pin 450, in both the contracted and expanded configuration of spring clip 460 to limit rotation of shank 420 within spring clip 460. Protrusion 470 includes one or more indentations 478 extending radially inward to laterally constrain pin 450 on planar surface 440 of rotation-limiting surface 430. Attempted rotation of shank 420 relative to spring clip 460 causes indentations 478 to bind pin 450 against planar surface 440, limiting rotation of shank 420 relative to spring clip 460. In various aspects, indentations 478 may be curved, as shown in FIG. 14, or may be substantially flat. Each of indentations 478 may be substantially rectangular and have a length (along longitudinal axis of shank 420) of about 6-25 mm, and in some aspects about 8 mm, and a width (transverse to longitudinal axis of shank 420) of about 3-7 mm, and in some aspects about 5 mm. In other aspects, indentations 478 may be shapes other than rectangular, e.g. pill-shaped, oval, trapezoidal, hexagonal, or the like.
FIGS. 12 and 14 show washer 490 disposed about shoulder 428 of shank 420, which is the position of washer 490 when cutting bit assembly 400 is secured in mounting bore 122 of tool holder 110. Prior to installation in tool holder, washer 490 surrounds spring clip 460 and retains spring clip 460 in the contracted configuration in the same manner as described herein in connection with the aspect of FIGS. 2-6.
FIG. 15 illustrates another aspect of cutting bit assembly 400 according to the present disclosure, which is substantially similar to the aspect of FIGS. 11-14. Corresponding components of cutting bit assembly 400 of FIGS. 11-14 are shown by the same reference numbers. FIG. 15 illustrates a cross-sectional view of cutting bit assembly 400 at the same cross-sectional location as the view of FIG. 13. The aspect of FIG. 15 differs from that of FIGS. 11-14 in that rotation limiting surface 430 includes a convex surface 442 recessed into body 422 of shank 420. Convex surface 442 may be not be coaxial with the remainder of the body 422 of shank 420, and convex surface 442 may have a radius different than (i.e., greater than or less than) the remainder of the body 422 of shank 420. Protrusion 470 includes a concave surface 479 configured to constrain pin 450 against convex surface 442. Concave surface 479 of protrusion 470 may be not be coaxial with the remainder of spring clip 460, and concave surface 479 may have a radius different than (i.e., greater than or less than) the remainder of spring clip 260. Concave surface 479 of protrusion 470 is configured to bind against pin 450 to limit or prohibit rotation of body 422 of shank 420 relative to spring clip 460.
FIG. 16 illustrates another aspect of cutting bit assembly 400 according to the present disclosure, which is substantially similar to the aspect of FIGS. 11-14. Corresponding components of cutting bit assembly 400 of FIGS. 11-14 are shown by the same reference numbers. FIG. 16 illustrates a cross-sectional view of cutting bit assembly 400 at the same cross-sectional location as the view of FIG. 13. The aspect of FIG. 16 differs from that of FIGS. 11-14 in that instead of having pin 450 as a separate component, rotation limiting surface 430 of the aspect of FIG. 16 includes an integrally formed projection 452. Projection 452 may extend longitudinally parallel to planar surface 440. Projection 452 may be in the shape of a semi-cylinder, i.e. a cylinder split longitudinally, and may generally interact with protrusion 470 of spring clip 460 in a manner similar to pin 450 of FIGS. 11-14. In particular, protrusion 470 of spring clip 460 is configured to bind against projection 452 to limit or prohibit rotation of body 422 of shank 420 relative to spring clip 460.
Industrial Applicability
The disclosed aspects of cutting bit assembly 200 as set forth in the present disclosure may be used for milling surfaces, such as asphalt roadways, when installed in milling drum 100 of a cold planer (also called a road mill or scarifier). As milling drum 100 rotates, cutting bit assembly 200 breaks the roadway surface into small pieces that can be removed and taken from the worksite. The interaction between rotation-limiting surface 230 of shank 220 and protrusions 270, 280 of spring clip 260 limits and/or prohibits rotation of cutting bit assembly 200 within tool holder 110, which may increase the life of cutting bit assembly 200 and/or tool holder 110. Particularly, by limiting or prohibiting rotation of cutting bit assembly 200, only the cutting side of cutting tip 210 experiences significant wear during milling operation. The non-cutting side of cutting tip 210 experiences less significant or negligible wear and therefore provides structural support for the cutting side of cutting tip 210. Furthermore, the lack of significant rotation of cutting bit assembly 200 results in low or negligible wear on end face 120 of tool holder 110.
Referring now to FIG. 17, illustrated is a flow diagram illustrating an exemplary method 600 for installing cutting bit assembly 200 in tool holder 110. Method 600 includes, at step 602, inserting shank 220 of cutting bit assembly 200 into mounting bore 122 of tool holder 110 with spring clip 260 in the contracted configuration. Washer 290 surrounds spring clip 260, as shown in FIG. 3, to hold spring clip in the contracted configuration. Proximal end 224 of shank 220 is inserted first into mounting bore 122, and is pressed into mounting bore 122 until washer 290 contacts end face 220 of tool holder 110.
Method 600 further includes, at step 604, releasing spring clip 260 from the contracted configuration so that spring clip 260 exerts a radially outward force against mounting bore 122 of tool holder 110, thereby causing spring clip 260 to be rotationally locked to mounting bore 122. Releasing spring clip 260 at step 604 may be achieved by pressing and/or hammering shank 220 fully into mounting bore 122 of tool holder 110 so that washer 290 is pressed onto shoulder 228 of shank 220. For example, shank 220 may be pressed into mounting bore 122 using a pneumatic gun equipped with an installation cup so as to not damage cutting tip 210. Washer 290 is slid along the outer surface of spring clip 260, until washer 290 clears spring clip 260, travels over shoulder 228, and engages flange 214 of cutting tip 210. As spring clip 260 is no longer radially constrained by washer 290 in the contracted configuration, spring clip 260 radially expands and frictionally engages mounting bore 122 of tool holder 110. The inner diameter of mounting bore 122 is less than the outer diameter of spring clip 260 in the expanded configuration, so the spring bias of spring clip 260 generates a frictional force against mounting bore 122. Thus, spring clip 260 is rotationally locked in mounting bore 122. Further, rotation-limiting surface 230 of shank 220 interacts with protrusion 270 of spring clip 260 to limit rotation of shank 220, and therefore limit rotation of cutting tip 210, relative to spring clip 260 and mounting bore 122.
In some aspects, attempted rotation of cutting tip 210 may increase the grip of spring clip 260 on mounting bore 122. In the aspect of FIGS. 2-6, rotation of shank 220 relative to spring clip 260 such that first planar 232 of shank 220 engages third planar surface 272 of spring clip 260 causes the radially outward force exerted by spring clip 260 on mounting bore 122 to increase. As such, the anti-rotation effect of spring clip 260 is enhanced. Similarly, rotation of shank 220 relative to spring clip 260 such that second planar 234 of shank 220 engages fourth planar surface 274 of spring clip 260 causes the force exerted by spring clip 260 on mounting bore 122 to increase.
As a result of limiting or prohibiting rotation of cutting bit assembly 200 during
operation of the cold planer, the life of cutting assembly 200 may be increased by limiting an area of the cutting tip 210 that experiences wear. Further, the life of tool holder 110 may be increased because there may be reduced wear caused by flange 214 and washer 290 rotating against end face 120.
Referring now to FIG. 18, illustrated is a flow diagram illustrating an exemplary method 700 for removing cutting bit assembly 200 from tool holder 110. Method 700 includes, at step 702, sliding shank 220 of cutting assembly 200 out of mounting bore 122 of tool holder 110.
Method 700 further includes, at step 704, sliding washer 290 from shoulder 228 of shank 220 over spring clip 260 as shank 220 is being slid out of mounting bore 122 to hold spring clip 260 is the contracted configuration. Beveled distal edge 266 of spring clip 260 and/or beveled proximal edge 292 of washer 290 guide washer 290 onto spring clip 260. That is, beveled distal edge 266 of spring clip 260 forces spring clip 260 into the contracted configuration as washer 290 is slid over distal edge 266 of spring clip 260. Alternatively or additionally, beveled proximal edge 292 of washer 290 forces spring clip 260 into the contracted configuration as washer 290 is slid over distal edge 266 of spring clip 260.
Step 704 may be performed at least partially concurrently with step 702. That is, washer 290 may be slid over spring clip 260 concurrently with shank 220 being slid out of mounting bore 122. In some aspects, steps 702 and 704 may be performed using a prying tool (not shown) inserted between washer 290 and flange 214 of cutting tip 210. Prying tool separates washer 290 from flange 214 and, concurrently, slides shank 220 out of mounting bore 122. Bevel on distal edge 298 outer diameter of washer 290 may assist in inserting prying tool between washer 290 and flange 214.
In some aspects, step 704 is completed when washer 290 is approximately centrally located along the length of spring clip 260, as shown in FIG. 3 or FIG. 8. Shank 220 may then be fully removed from mounting bore 122, without further moving washer 290. Thus, once cutting bit assembly 200 has been entirely removed from tool holder 110, washer 290 retains spring clip 260 in the contracted configuration so that cutting bit assembly 200 can be re-used (i.e. inserted into another tool holder).
While the foregoing descriptions of methods 600 and 700 were described in conjunction with the aspect of cutting bit assembly 200 illustrated in FIGS. 2-6, it will be understood by those skilled in the art that methods 600 and 700 could be equally utilized with the aspects of cutting bit assembly 300 of FIGS. 7-10 and cutting bit assembly 400 of FIGS. 11-16.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed system without departing from the scope of the disclosure. Other embodiments of the system will be apparent to those skilled in the art from consideration of the specification and practice of the system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents. Claims What is claimed is:
- 1 A cutting bit assembly for attachment to a tool holder of a milling-type machine, the cutting bit assembly comprising:
- a cutting tip;
- a generally cylindrical shank extending from the cutting tip and comprising a rotation-limiting surface; and
- a spring clip surrounding a body of the shank and comprising a protrusion configured to interact with the rotation-limiting surface of the shank to limit rotation of the shank relative to the spring clip, wherein the spring clip includes a contracted configuration and an expanded configuration, and in both the contracted configuration and the expanded configuration the protrusion interacts with the rotation-limiting surface.
Patent Application
20240383051
