Patent Application
20060206233
Not applicable.
Not applicable.
The present invention relates to a method and apparatus for obtaining a desired cut in a workpiece. More particularly, this invention relates to a cutting apparatus having a base, a scanner coupled with the base for determining the profile of a workpiece, a cutting member selectively movable with respect to the base as a result of information obtained from the user and/or the scanning process, and a computing device for controlling movement of the cutting apparatus during use.
One of the most difficult construction projects for most people is finish carpentry. While most people can readily learn how to cut miter cuts for making miter joints, miter cuts do not always create the best joint. For example, while a miter joint might be the preferred joint for framing the casing around a door or window, a miter joint is not the preferred joint for use in an inside corner situation for molding, a cope joint is.
Cope joints are created by cutting the profile of one piece of molding into the end of another piece of molding so that when the two pieces are placed together (usually in a corner and at right angles to one another) they mate to form an almost invisible joint. Further, and unlike miter joints, cope joints do not open up like miter joints as the molding dries and shrinks. For these reasons, cope joints are often a preferred method of installing molding and trim work. Unfortunately, cope cuts are difficult to make and require a high skill level to accomplish using traditional methods.
In addition to requiring more skill, cope cuts are more labor intensive and take more time to make using traditional methods than a simple miter cut. While initial cuts can occasionally be made with a power miter saw, cope cuts often must be finished by hand with the use of a coping saw. Even if a craftsman uses a powered cutting tool to finish the cope cut, most arrangements still require the contour or molding profile to be cut free hand by the craftsman. This often leads to imprecise cuts and errors in all but those cuts performed by the most skilled craftsman and, occasionally, to unusable cuts resulting in wasted time and materials. Consequently, numerous attempts have been made to speed up the process of and to assist craftsmen in cutting cope joints.
U.S. Pat. No. 4,355,557, for example, discloses an apparatus for cutting molding that uses a plurality of templates. A drawback of this device is the necessity of a template for each type of molding the user desires to cut. U.S. Pat. No. 5,136,904 discloses a motorized coping saw for creating cope cuts. While this device would reduce fatigue over the conventional hand saw method, this device still, however, requires the operator to have the skill necessary to cut out the profile free hand, thus leading to errors. U.S. Pat. No. 5,853,036 discloses a motorized apparatus for cutting contoured molding. This apparatus allows a skilled workman to manually emulate the molding contour using a power cutting tool. While this device represents an improvement over the prior art in that it holds the cutting apparatus securely, the craftsman must still create the cut free hand, thereby leading to errors, wasted time and wasted material.
Therefore, there is a need for a device which can ascertain the profile of a piece of molding and then automatically move a cutting member through a path corresponding to the profile to create cope cuts that match the profile quickly and exactly. The present invention fills these and other needs.
In order to overcome the above stated problems and limitations, and to achieve the noted advantages, there is provided a motorized workpiece cutting apparatus having a motorized cutting member moveably and operably coupled with a base via a support member. The base includes a base frame upon which a first carriage is slidably mounted. The first carriage is moveable in a first direction by activation of a stepper motor. A second carriage is supported on and moveably coupled with the first carriage in a second direction, which is perpendicular to the first direction of the first carriage. A second stepper motor controls movement of the second carriage.
The apparatus also includes a scanner for scanning the profile of a workpiece desired to be cut and a computing device for controlling the apparatus. A user may instruct the apparatus to scan the profile of a piece of molding and store the profile in a memory component of the computing device. The user can then inform the computing device of the type of cut the user wishes to make in the subject molding. The user can then adjust the orientation of the cutting member as necessary, depending on the type of cut the user wishes to make, and place the molding on an upper surface of the base in preparation for the cutting process. When instructed to do so by the user, the computing device will control the cutting function by activating the cutting member and controlling the movement of the cutting member through the molding by way of sending the appropriate signals to the appropriate stepper motors to move the cutting apparatus in both the first and second directions. This device is well adapted to cut numerous types of cuts to create a wide variety of joints, including cutting a cope joint by moving the cutting member through a cutting path, which corresponds, to the scanned profile of the molding being cut.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.
The features of the invention noted above are explained in more detail with reference to the embodiments illustrated in the attached drawing figures, in which like reference numerals denote like elements, in which
Referring now to the drawings in more detail and initially to
The base 12, as best illustrated in
A portion of the plate member 26 is cut away to provide a notch 34. The notch 34 receives a portion of the cutting member 14 and permits the cutting member to freely move around therein during use. The notch 34 also provides an opening through the work surface 32 into the base 12. The plate member 26 is preferably coupled with the base frame 22 via brackets 36 with screws (not shown) which pass through apertures 38 in the plate member 26, in a manner well known in the art.
The base 12 also preferably includes a fence 40 against which the workpiece 18 is abutted during use, as best illustrated in
Turning now to
The base 12 includes a first carriage 68 and a second carriage 70. The support 16 is selectively coupled with the second carriage 70 and the carriages 68, 70 cooperate with one another to provide movement of the cutting member 14 during operation of the apparatus 10, as described in more detail below.
The first carriage 68 is designed to provide movement of the cutting member 14 from front to back, i.e., along the X-axis illustrated in
Movement of the first carriage 68 along the X-axis is accomplished by a first or X stepper motor 84 which is coupled with a threaded rod 86 having its longitudinal axis parallel with the X axis of the apparatus 10. The threaded rod or drive shaft 86 extends from the back wall 64 to the front wall 62, while passing through a portion of the first carriage 68. In the illustrated embodiment, the X drive shaft 86 passes through the front and rear arms 76, 78 of the first carriage 68. The arms 76, 78 are provided with bushings 88 which receive the rod 86. The bushings 88 are internally threaded and cooperate with the threaded rod 86 such that when the stepper motor 84 rotates the threaded rod 86, the first carriage 68 is moved along the longitudinal axis of the rod 86, which corresponds with the X-axis of the apparatus 10.
The second carriage 70, as best illustrated in
Guide blocks 100 each having a bore 102 there through and are preferably provided adjacent each of the openings 98 such that the bores 102 are coaxial with the openings 98 for receiving the arms 76, 78 to help support the second carriage 70 on the first carriage 68.
The second carriage 70 is moved along the first carriage 68 by way of a second or Y stepper motor 104 (
The support 16, as best illustrated in
The adjustable coupling mechanism 114 preferably includes a bolt 116 having a user engagable knob 118. The bolt 116 passes through a slot 120 in the support, bore 122 in an adjustment block 124, and a slot 126 in the back cross arm 96 of the second carriage 70. A nut 128 is threadably received on the free end of the bolt 116.
The adjustable coupling mechanism 114 permits the user to adjust the orientation of the cutting member 14 with respect to the work surface 32. For example, because the slot 120 in the support 16 is elongate in nature and in a generally vertical orientation, the support 16 can be rotated so that a forward end 132 of the upper arm 108 is moved toward the front 48 of the base 12 while a forward end 134 of the lower arm 110 is moved away from the front 48 of the base 12. While the support 16 is being rotated, the slot 120 slides along the bolt 16. This motion causes the cutting member 14 to be tilted forward and therefore changes the forward tilt or bevel angle. This arrangement makes it so that the cutting blade 160 pivots about a point that is in the plane of the work surface 32. A gauge 136 can be provided to measure the angle of forward tilt by providing indicia 138 on a side of the support 16.
The forward tilt or bevel angle is set in connection with the adjustment block 124 by way of wings 140 which are used to clamp the adjoining section 112 of the support 16 to the adjustment block 124. The wings 140 have a ridge 141 on their inner surface that cooperates with a groove 143 in each of the sides of the adjoining section 112. A bolt 142 having a lever arm 144 passes through the wings 140 and the adjustment block 124 and cooperates with a nut 146 to pinch the adjoining section 112 of the support 16 between the wings 140 to thereby set the bevel angle.
The adjustable coupling mechanism 114 also permits a user to selectively vary the side-to-side or back cut angle. When assembled, a front face 148 of the adjustment block 124 abuts a rear surface of the back cross arm 96 of the second carriage 70. An arcuate channel 150 in the front face 148 of the adjustment block 124 aligns with and cooperates with a corresponding arcuate ridge (not shown) on the rear face of the back cross-arm 96. The support 16 is partially received in a groove 152 in a rear face of the adjustment block 124 and is clamped to the adjustment block 124 via the wings 140. With the bolt 116 loose, the adjustment block 124 can pivot about the bolt 116 to tilt the upper arm 108 from side to side and thereby adjust the bevel or back cut angle. The amount of back cut can be determined by providing a gauge 154 on the front surface of the back cross arm 96 of the second carriage 70.
The nut 128 is received in and slides in an enlarged portion 156 of the slot 126. The arcuate channel 150 and the arcuate slot 126 are concentric arcs with the slot 126 having a smaller radius of curvature than the arcuate channel 150. By providing the channel 150 and the slot 126, the support 16 does not pivot about the longitudinal axis of the bolt 116, but instead pivots about a pivot point above the top of the adjustment block 124. This arrangement makes it so that the cutting blade 160 pivots about a point that is in the plane of the work surface 32 instead of about a point below the work surface 32.
The cutting member 14 (
In that regard, the illustrated embodiment discloses a double-shanked spiral bit. This bit has been found beneficial in cutting a smooth cut through molding as well as producing a thin kerf. Accordingly, the cutting member 14 includes an upper collet 164 and a lower collet 166. The lower collet 166 is located on the lower arm 10 of the support 16 adjacent the forward end 134. The upper collet 164 is directly below the motor 158 and is axially aligned with the lower collet 166. The motor 158 is coupled with the forward end 132 of the upper arm 108. This can be accomplished in any traditional means, but is illustrated as being done by a pair of screws 168 through a collar 169 to clamp a housing 170 of the motor 158 between the collar 169 and the forward end 132 of the upper arm 108.
The scanner 20 is preferably stationary and coupled with the base frame 22 by way of a bracket 172. While the scanner 20 is disclosed and illustrated in
The scanner 20 is mounted such that it is positioned above a small moveable table or sled 174. The sled 174, for reasons discussed in more detail below, is designed to hold a sample portion 176 of the workpiece 18 desired to be cut. The sled 174 has a fence 178 and may include a clamp (not shown) for securing the sample portion 176 to the sled 174. The sled 174 is coupled with the right end plate 72 of the first carriage 68 such that activation of the X stepper motor 84 moves the sled 174 with the first carriage 68 along the X-axis.
Turning now to
As illustrated in
The focal length of the focusing lens 200 (i.e. the distance between the focusing lens 200 and the focal point 212) is a predetermined and set distance. The beam 210 then reflects off of the upper surface 214 of the sample portion 176 toward the collecting lens 202, which focuses the beam 210 on the beam splitter 204. The beam 210 is then split by the beam splitter 204 into two parts with the first part 216 being reflected to the right sensor 206 and the second part 218 being reflected to the left sensor 208. The sensors 206, 208 can be phototransistor sensors or other photo sensors of adequate bandwidth. The LED 196 and the sensors 206, 208 are electronically coupled with the electrical connection 192 via wires (not shown).
The Z stepper motor 186 includes a rotatable drive shaft 220. The drive shaft 220 is supported in a generally horizontal orientation and coupled with the bracket 172 via a pair of bearings 222. A torque arm 224 is coupled at its proximal end with the drive shaft 220 in a generally perpendicular orientation. A distal end of the torque arm 224 contacts a pin 225 which is fixed in a bearing 226 of a mount 228 on a side of the housing 190 of the optical sensor 184. A stiff flat spring 229, attached to the torque arm 224, biases the hard surface of the distal end of the torque arm 224 against the pin 225, thus providing a zero hysteresis connection between the torque arm 224 and the housing 190. As the drive shaft 220 is rotated by the Z stepper motor 186, for reasons discussed in more detail below, the torque arm 224 slides against the pin 225 of the bearing 226 and will raise or lower the optical scanner 184. The flexures 188 cooperate with each other in a manner similar to parallel linkage arms to maintain the optical scanner 184 in a generally horizontal orientation during the vertical movement of the optical sensor 184.
The operation of the scanner 20 will now be described in detail. In that regard, the scanning process usually begins by the user placing a sample portion 176 of the workpiece 18 to be cut on the sled 174 that is located under the optical sensor 184. The sample portion 176 is laid flat on the sled 174 such that a backside 230 of the sample portion 176 rests on the sled 174. The sample portion is pushed up against the fence 178, as illustrated in
The sled 174 is preferably in a rearward most position at the start of the scan such that the beam of light 210 emitted from the optical sensor 184 shines down upon an upper surface 232 of the fence 178. This represents a known distance and setting for the optical sensor 184 and functions as a reference point. In this position, the optical sensor will be in a null condition. This null condition is better understood by referring to
The computing device 194 then activates the X stepper motor 84 thereby causing the rod 86 to rotate. As the rod 86 rotates, the first carriage 68 moves from its rearward most position toward the front 48 of the base 12. As the first carriage 68 moves forward, the sled 174, and consequently the sample portion 176, moves under the optical sensor 184 in the direction indicated by the arrow 234 in
In response to this difference, the computing device 194 emits an appropriate signal to the Z stepper motor 186 to rotate the shaft 220 to raise or lower the optical sensor 184 to put the beam 210 back into focus on the upper surface 214 of the sample portion 176 such that the point 212 is centered and this light is reflected directly into the collecting lens and split equally between the two sensors 208 and 206. Thus the sensor is once again at its null condition. Accordingly, as the sample portion 176 moves under the optical sensor 184, the Z stepper motor 186, by way of signals from the computing device 194, moves the optical sensor 184 up and down to keep the sensor in its null condition and hence at a constant distance above the sample portion 176.
In other words, the optical sensor moves up and down as a sample portion is moved there under in a path that follows or mirrors the profile of the sample portion 176. Once the sled 174 has been moved far enough forward that the trailing edge of the sample portion 176 is reached, the beam will hit an upper surface 235 of the sled 174 upon which the sample portion 176 rests. The computing device 194 interprets the sensor's position as the edge of the sample portion and terminates the scan process. The up and down movement, via plus or minus z-steps to monitor null, of the optical sensor 184 during the course of the scan is stored in a memory component of the computing device 194 as a change in the Z-axis or a Δ Z with respect to the X movement. It should be noted that the z-stepper rotary steps do not linearly correlate to the optical sensor's 184 linear z-height steps due to the nature of the linkage between the two. Therefore the sensor's 184 movement is linearized with the use of a look up table to precisely correlate the rotary movement of z-stepper motor 186 to the linear motion of the optical scanner sensor head 184. The computing device 194 then signals the X motor 84 to rotate in the opposite direction to return first carriage 68, and in turn the sled 174, back to the start position.
With the profile of the sample portion 176 now scanned and stored in the memory component of the processor 194, the user can now cut or cope the workpiece 18 as desired. For example, if the user desires to cope the left end of the workpiece 18 so that it will fit into a standard 90 degree corner and butt up against another piece of workpiece having the same profile and being perpendicular thereto, the user places the workpiece desired to be coped onto the work surface 32 of the apparatus and abuts the workpiece 18 up against the fence 40. The workpiece 18 is then clamped down by one of the clamps 42.
Once the workpiece is in position, the user informs the computing device 194 of the apparatus 10 of the desired cut, as discussed in greater detail below, by way of the buttons 46 on the control panel 44 and the cut is initiated. The motor 158 is then activated thereby rotating the spiral cutting bit 160 and the X stepper motor 84 would be activated to rotate the rod 86 to move the first carriage 68 toward the front 48 of the base 12. Continuing with the example of the illustrated chair rail that was previously scanned, part of the resulting cut is illustrated in
In this example, since the workpiece is abutted flat up against a wall and mounted thereto, the bevel angle, i.e., the angle at which the cutting member 14 and the bit 160 are tilted front to back, is zero. In other words, no bevel angle is needed and the bit 160 is in a plane that is perpendicular to the X axis. However, most carpenters prefer to back cut their cope joints a little so that only the outer edge of the profile abuts the profile of the adjoining piece. Accordingly, to provide for the back cut, the cutting member 14 and hence the cutting blade 160 would be tilted to the left side 54 of the base 12 five to 15 degrees from vertical. This is accomplished manually by loosening the user engagable knob 118, rotating the support 16 about the bolt 116 until the desired back cut angle is achieved, as indicated by the gauge 154, and retightening the knob 118 to lock the cutting member 14 in place at the desired angle.
The right side of
While the discussion above with regards to scanning and coping a workpiece having a desired profile was done in connection with a piece of chair rail that is mounted flush up against the wall, the present apparatus also permits the cutting of items which are not secured flat to the wall, such as crown molding (
When the desired cope angle is reached, as indicated by the cope angle gauge 136 on the side of support 16, the bolt 142 is tightened to clamp the support 16 between the wings 140 to set the cope angle. The bolt 116 is also tightened to set the back cut angle. The particular embodiment of the adjustable coupling mechanism 114 described and illustrated herein permits a user to set the cope angle necessary for a workpiece of a particular profile and then be able to tilt the cutting member 14 from side to side for cutting left or right end cuts without having to readjust the cope angle.
For example, if the apparatus 10 is used to cut 52 degree crown molding (a widely available crown molding in which the crown molding, when properly installed, tilts back 52 degrees from being perpendicular to the wall or 38° out from the wall), as illustrated in
Once the user has pushed the cope button 240, the indicator 244 thereon turns green and the indicators on the outside miter button 246 and the casing miter 248 turn off. The indicators 244 on an input molding angle button 250 and an input button 251 would be energized red and the user would know to input the angle of the molding to be coped at step 252. The user would then press up or down adjustment buttons 254 to increase or decrease, respectively, the number shown in a display 256 of the input button 251. Once the number on the display 256 matches the angle of the molding, the user would press the input molding angle button 250 and the indicator 244 on button 250 would turn green and the indicator 244 on input button 251 would turn off.
If the profile of the molding or workpiece 18 being cut is not already stored in a memory component of the computing device 194, the user would need to next scan the profile of the workpiece 18. Accordingly, the user would, at step 258, place the workpiece 18 to be coped on the left side of work surface 32 up against the fence 40 and clamp the workpiece 18 down with the left clamp 42 to cut a sample portion 176. The user would then cut off a sample portion 176 at step 260 by pressing a cutoff sample button 262. Computing device 194 would then activate the motor 158 to rotate the cutting blade 160. The cutting blade 160 should be in a vertical orientation (i.e., no back cut angle or bevel angle) to make a straight cut through the workpiece 18 as the X-stepper motor 84 moves the first carriage 68 and turn the cutting blade 160 toward the front 48 of the apparatus 10. It should be noted that the sample portion 176 could be obtained from the workpiece 18 by using a separate device, such as a powered miter saw, and steps 258 and 260 could be skipped.
The sample portion 176 is placed on the sled 174 at step 264. At step 266 the sample portion 176 is scanned by the scanner 20 once the user presses a scan sample button 268. The resulting profile of the sample portion 176 and in turn the workpiece 18 is then stored in a memory component of the computing device 194.
Upon completion of the scan, the indicator 244 on a select back cut angle button 270 and the indicator 244 on the input button 251 are energized red. The user then inputs the back cut angle at step 272 by way of the adjustment buttons 254. Once the display 256 indicates the appropriate back cut angle, the user presses the select back cut angle button 270 and the indicator 244 thereon is changed to green. The computing device 194 then sends signals to a left button 274 and a right button 276 to energize their indicators to red. At step 278, the user informs the computing device 194 whether the desired cut will be on the right end or the left end of the workpiece 18 by pressing either the left button 274 or the right button 276. Once the button 274 or 276 is pressed, the indicator 244 on that button goes green and the indicator on the other button turns off.
At step 280, the apparatus 10 displays the settings for the cut in display 282. At step 284, user sets the machine angles. In the illustrated embodiment, the angles, namely the cope angle and the back cut angle, are manually set by adjusting the bolts 142 and 116, respectively, of the adjustable coupling mechanism 114. It is within the scope of the present invention to provide encoders or axis sensors to provide closed loop feedback to the end user and/or control system to be sure axes angles are set properly before starting a cut. It is also well within the scope of the present invention to, in an alternate embodiment, automatically set the machine angles by way of entering the appropriate information into the computing device 194 via the control panel 44 such that the computing device 194 controls motors (not shown) which move the support 16 to place the cutting member 14 in the desired orientation.
Once the machine settings are displayed at step 280, the indicator 244 on a start cut button 286 is energized red to indicate the device is ready to make the cut. This indication lets the user know to set the machine angles at step 284 and load the workpiece 18 for cutting. At step 288, the workpiece or molding 18 to be cut is placed on the work surface 32 in the desired orientation to make the left or right cut as previously indicated, and clamped down to the work surface 32 while abutting the fence 40 with one of the clamps 42. Once the workpiece 18 is clamped down, the user presses the start cut button 286 at step 290 and the computing device 194 initiates and controls the cutting sequence as described above. Once the cut is complete, the cutting member 14 is returned to its rest position where the cutting blade 160 is rearward of the fence 40.
The control panel 44 also preferably includes a plurality of memory buttons 292 which can be used to store scanned profiles and/or settings separately or in combination with one another. For example, one of the memory buttons 292 could be pressed after step 290 above to store all of the settings and the profile of the workpiece that was cut. In the future, when the user desires to make a similar cut on a workpiece 18 having the same profile, the user can simply press that same memory button 292 and the computing device 194 will “fill in” all of the settings and recall a profile of that particular workpiece from memory. The user could then simply set the machine angles, put the workpiece 18 on the apparatus, and push the start button 286. Alternatively, a memory button 292 could be pressed at the beginning of a scan sequence to store only the profile, as discussed in greater detail below.
If the user desires to make an outside miter cut at step 238, the user presses the outside miter button 246 at step 294. Once the user presses the outside miter button 246, the indicator 244 thereon preferably turns green and indicators 244 on an input corner angle button 296 and on the input button 251 turn red. Once the user has input the angle of the corner around which the molding is to be installed by way of the adjustment buttons 254, so that the corner angle is displayed in the display 256, the user presses, at step 298, the input corner angle button 296 and the indicator 244 thereon turns green. Simultaneously the indicators 244 on input molding angle button 250 and input button 251 turn red. Once the user has input the molding angle by way of the adjustment buttons 254, so that the molding angle is displayed in display 256, the user presses, at step 252, the input molding angle button 250 and the indicator 244 thereon turns green and the indicator 244 on the input button 251 turns off. The user then selects a left or right cut at step 278. With all of the appropriate settings displayed at step 280, the user sets the machine angles at 284 and loads the material at 288. The user initiates the cut by pressing the start cut button 286 at step 290.
In addition to the ability to cut cope cuts and outside miter cuts, the apparatus 10 also has the ability to cut casing miter cuts, such as those necessary for framing around a window or door. If the user desires to cut a casing miter joint at step 238, the user would press the casing miter button 248 at step 300. In the illustrated embodiment, upon pressing the casing miter button 248, the indicator 244 thereon would turn from red to green, the indicators 244 on the cope button 240 and the outside miter button 246 would turn off, and the indicators 244 on the input button 251 and on a select miter angle button 302 would turn red. Once the display 256 shows the proper miter angle as input by the user via the adjustment buttons 254, the user presses the select miter angle button 302 at step 304. From this point, the user selects whether a left or right cut is desired at step 278 and proceeds through the remaining steps, as discussed above and as illustrated at
Once the user has selected the memory button 292 at step 314, the process for scanning the profile of a workpiece generally follows the steps described in greater detail above and as illustrated in
As one skilled in the art will appreciate, the computing device 194 disclosed herein could be any type of computing device capable of performing the disclosed functions. As readily understood, the computing device 194 includes a processor and a memory component. The memory component can store data momentarily, temporarily, or permanently and can be of any type known in the art.
Many variations can be made to the illustrated embodiment of the present invention without departing from the scope of the present invention. Such modifications are within the scope of the present invention. For example, while the user is notified of the steps of the desired information in the illustrated embodiment by way of the indicators 244 on the buttons 46, an additional display device could be placed on the control panel 44, such as an LCD, to convey instructions to the user and to indicate the particular information requested at each step. Other modifications would be readily apparent to one of ordinary skill in the art, but would not depart from the scope of the present invention.
For example,
The apparatus 10′ is illustrated in
A hold down pad 336 is provided on the clamp arm 326 adjacent a distal end 338 thereof. The hold down pad 336 is movable along the length of the clamp arm 326 to permit the user to place the hold down pad 336 in the best location for holding down a workpiece 18 with a particular profile.
A user engagable knob 340 is provided at a distal end 342 of the lever arm 330 to permit the user to move the clamp arm 326 between a raised position, for positioning a workpiece 18 on the work surface 32, and a clamping position, as illustrated in
A bracket 344 extends downwardly from the work surface 32 and includes an arcuate section 346 having a plurality of transverse grooves in an outer surface thereof to provide teeth 348. A sleeve 350 is positioned on the rod 322 adjacent the knob 340. Sleeve 350 includes a longitudinal rib extended outwardly therefrom that provides a pawl (not shown) for selective engagement with the teeth 348.
In use, the operator raises the lever arm 330 up towards the work surface 32 to increase the distance between the hold down pad 336 and the work surface 32 to permit a workpiece 32 to be cut to be placed adjacent the fence 40 and underneath the clamp arm 326 of the hold down 42′. Once the workpiece 18 is in the desired location, the user pushes downward on the knob 340 to rotate the hold down pad 336 into engagement with an upper surface of the workpiece 18. If needed, the user can move the hold down pad 336 along the clamp arm 326 to position the hold down pad so that it abuts the workpiece 18 in a desired location. Once the hold down pad 336 is in the desired location, the user can secure the position of the hold down clamp 336 on the clamp arm 326 by tightening a screw 352 which presses against a flattened portion 354 of the rod 322. The screw 352 could have a user engagable knob similar to knob 118.
Once the hold down pad 336 is in contact with the upper surface of the workpiece 18, the user can rotate the lever arm 330 further downward to clamp the workpiece 18 against the work surface 32. The additional downward movement of the lever arm 330 causes the rod 322 to twist and act like a spring to provide the hold down force of the clamp 42′. The further the lever arm 330 is moved downward, the greater the hold down pressure provided by the clamp 42′. When the user has reached the desired clamping pressure, the user engages the pawl of the sleeve 350 with the adjacent teeth 348 of the arcuate section 346. The pawl and teeth 348 cooperate to hold the lever arm 330, and turn the clamp arm 326, in place during operation of the apparatus 10′. Once the cut has been made, the user can remove the workpiece 18 by disengaging the pawl from the teeth 348.
The second embodiment 10′ also discloses a number of other modifications or alterations from the first embodiment. For example, the scanner 20 is positioned within and protected by a housing 356. An opening (not shown) is provided in the plate member 26′ through which the scanner 20 may read the profile of the sample portion 176 as it passes there below. The sled 174′ in the second embodiment is provided with an outer sidewall 358 for ensuring that the sample portion 176 remains on the sled 174 during the scanning process.
The second embodiment also shows the use of extruded members 358 to form the base frame 22′. The extruded members could be extruded aluminum to lighten the weight of the apparatus 10′. The extruded members 358 could also be used as the front and rear arms 76′, 78′ of the first carriage 68. The extruded members 358 naturally provide channels therein for guiding sliding members as well as attaching non-sliding members, such as brackets 36′.
Lastly, the second embodiment of the apparatus 10′ discloses a cutting blade and workpiece support 360. The support 360 is coupled with the second carriage 70 and spans between the right and left cross arms 90, 92. The support includes a crossbar 362, positioned on the second carriage 70 such that it travels underneath the work surface 32 during use, and a U-shaped guide 364 positioned on top of and at the center of the crossbar 362. An upper surface 366 of the guide 364 is preferably in the same plane as or slightly below the upper surface 28 of the work surface 32.
In that regard,
The tool-less, pushbutton collet 382 includes an annular housing 384 that is coupled with a distal end of the lower arm 110′ of the support 16′. Bearings 386 are provided inside the housing 384 and rotatably support a collet holder 388. The collet holder 388 is generally cylindrical in shape and includes a longitudinal bore 390 therethrough. The bore 390 includes a flared portion 392 adjacent the upper end 394 of the collet holder 388 for receiving a tapered portion 396 of a collet member 398. The collet member 398 is elongate in nature and is received in the longitudinal bore 390 of the collet holder 388. The collet member 398 has a central longitudinal bore 400 therethrough and has a user engagable button 402 opposite the taper portion 396. A spring 404 surrounds a portion of the collet member 398 and is positioned between the button 402 and the collet holder 388 to bias the collet member 398 into seating engagement with the collet holder 388.
To install a new cutting blade 160, the cutting blade 160 is positioned in the longitudinal bore 400 through its opening in the button 402. The cutting blade 160 is pushed into and through the pushbutton collet 382 until the upper shank thereof reaches and is received in the upper collet 164. The upper collet 164 is tightened via wrenches on one of the shanks of the cutting blade 160 to ensure that the upper collet 164 transmits the torque of the motor 158 to the cutting blade 160. When the button 402 is released, the spring 404 in the pushbutton collet 382 pulls the tapered portion 396 of the collet member 398 into the flared portion 392 of the collet holder 388, thereby pinching the lower shank of the cutting blade 160 therein and centering the cutting blade 160 on its axis of rotation and preventing radial movement of the lower end of the cutting blade 160.
During operation, the cylindrical collet holder 388 of the pushbutton collet 382 rotates with the cutting blade 160 in the bearings 386. By attaching a plurality of blades 412 to the outer surface of the collet holder 388, rotation of the cutting blade 160 causes the blades 412 to rotate about the central longitudinal axis of the cutting blade 160, thereby creating the centrifugal fan 408. By placing the dust shroud 410 around the centrifugal fan 408, airflow can be directed from the blades 412 through an airflow passage 414 to a discharge tube 416, as illustrated by an arrow in
The downward spiral configuration of the cutting blade 160 and gravity work together to start moving the saw dust from the cutting operation in a downward direction. While this arrangement may provide sufficient dust handling for certain operations, the centrifugal fan 408 of the dust collection system 406 creates a downward airflow that draws the saw dust through the dust shroud 410 and expels it out the discharge tube 416 for improved dust handling capabilities. While the saw dust expelled from the discharge tube 416 can be left to simply fall out the bottom of the apparatus 10 and collect in a pile, the discharge tube 416 can be configured to have a hose of a vacuum or a simple dust bag connected thereto. To facilitate such a connection, the discharge tube 416 could be circular with the industry standard one inch outside diameter for connection to a vacuum or dust bag.
As discussed above, the cutting blade 160 is preferably a double shanked downward cutting spiral bit. In that regard,
While a conventional single shanked rotary saw bit could be used in the cutting member 14 of the apparatus 10, the double shank cutting blade 160 has been found to provide superior rigidity and less deflection than a single shank cutting blade of comparable diameter by virtue of the fact that the double shank design provides for support on both ends of the cutting blade. The improved support and stiffness permits decreasing the diameter of the cutting blade 160. In that regard, the cutting blade can be made to have an industry standard ⅛ inch diameter so that the upper collet 164 could be a readily available item. The smaller diameter of the cutting blade 160 permits the apparatus 10 to cut finer details in intricate moldings and workpieces 18. Additionally, the increased stiffness provided by the double collet arrangement has been found to result in a longer blade life.
In addition to the scanner 20 discussed above,
The sample portion 176 is also oriented such that a rear surface 442 of the sample portion abuts a vertical wall 444 of the rabbit 432. This also orients the sample portion 176 such that the profile of the sample portion 176 is in near the middle of the opening 430. Looking at
The scanner 428 is then coupled with the second carriage 70 such that the X and Y stepper motors 84, 104 can move the scanner 428 back and forth underneath the sample portion 176 and along the edge of its profile during the scanning process to determine the profile of the workpiece 18.
The scanner 428 includes a light emitting diode 446 for emitting a beam 448 that is focused on the end 440 of the sample portion 176 positioned in the opening 430. The beam 448 is focused vertically upwards by a first lens 450 at a slight angle. A second lens 452 focuses the reflection of the beam off the end 440 of the sample portion 176 onto a photo detector or photo transistor sensor 454. The beam 448 is then used as an edge detection signal.
In that regard, the beam 448 is focused on the end 440 of the sample portion 176. The Y-stepper motor 104 is then activated until the beam 448 goes off the edge of the profile and is no longer reflected back into the sensor 454. The Y-stepper motor 104 is then reversed until it is detected that the beam 448 is focused back on the end 440 of the sample portion 176. The X-stepper motor 84 is then activated to move the scanner 428 forward and the process is repeated. In this manner, the Δ Z data for the profile of the workpiece 18 is developed from the position the Y-stepper motor 104 (and hence the scanner 428 on the second carriage 70) is in each time the edge of the profile is acquired. The detector 454 outputs a signal that is sent to an adjustable threshold comparator (not shown). The comparator then sends a signal to the computing device 194.
As a further modification, both the scanner 20 and the scanner 428 can be deployed with a synchronous detector scheme to make the scanner 20, 428 immune to interference from ambient light reflecting off the surface of the sample portion 176 during the scanning process.
Synchronous detection is a signal acquisition technique used to very effectively reject unwanted ambient or background “noise” while cleanly acquiring a desired signal. The technique is applicable to any type of signal source such as light, sound, magnetic, etc. that can be rapidly pulsed on and off, usually at a 50% duty cycle. In one embodiment of a synchronous detection system, and with reference to the scanner 20 of the first embodiment, the beam 210 is synchronously detected at a rate of approximately 5 kHz, which is more than 10 times the variation rate of the beam 210 or existing light noise. The beam 210, preferably from a 950 nm infrared LED because of it's high efficiency, angularly impinges an approximately 0.7 mm focused spot of light 212 on the upper surface 214 of the sample portion 176. The LED 196 is turned on and off about 5000 times per second with a 50% duty cycle. Also impinging on the upper surface 214 of the sample portion 176 in the area of the 0.7 mm focal point 212 of the beam 210 is noise light from various sources, such as fluorescent lights and daylight.
The scanner 20 operates in a closed loop where the Z-height is positionally maintained such that the focused spot or focal point 212 is always directly under the collecting lens 202 that focuses the beam 210 on the splitter 204 for a 50/50 split. Noise light undesirably collected in the vicinity of the spot 212 would not be uniform in position or intensity, thus leading to Z-height error when seeking a null difference signal from the splitter 204.
Synchronous detection can effectively cancel out the unwanted noise light that undesirably makes its way past the beam splitter 204 to the two differencing photo-transistors 206, 208 whose outputs are subtracted to form the output signal from the scanner 20 to the computing device 194. Note that for any given circumstance, noise light will flood the spot area 212 at all times during operation of the apparatus 10.
Synchronous detection employs a sample and hold (“S&H”) technique. In one embodiment, a S&H amplifier has a gating switch that can be closed to charge an input capacitor and opened to maintain that sampled voltage level until the next sample cycle. The S&H amplifier has high input impedance to prevent capacitor discharge between cycles. A total of four sample & hold amplifiers are connected to the differencing photo-transistors; two sample (Left) with LED On/Off, two sample (Right) with LED On/Off.
In use, an example of one cycle of an embodiment of a 5 kHz synchronous detection system proceeds as follows:
The LED is turned ON; simultaneously two sampling switches (e.g., CMOS) close for 100 microseconds thus sampling the desired LED signal plus the unwanted noise difference signals from the two differencing photo-transistors. The LED is turned OFF; simultaneously two other sampling switches sample just the noise from the two differencing photo-transistors for 100 microseconds. Two inverting amplifiers then invert the left and right samples and the hold noise light signals which are added to the S&H signals that have the good signal plus the noise. The identical plus and minus noise signals cancel each other out and leave only the desired LED difference signal which is then the output of the scanner that is sent to the computing device.
It should be noted that it is assumed in the example that neither the noise or the desired difference signal changes during one clock cycle of 200 microseconds. In this embodiment, the desired Z-height signal is in the low Hz range. Fluorescent lights flicker at 120 Hz with components at much higher frequencies that synchronous detection is able to effectively remove. The scheme is effective as long as the amplifiers, which are working in a linear range, are not saturated.
Also, in the example embodiment, the gating for the S&H amplifiers is bracketed at 70 microseconds in the middle of each 100 microseconds ½ cycle of LED On/Off illumination to generate safe switching margins. In addition some capacitive smoothing is accomplished at the output of the final 4-channel summing amplifier that subsequently feeds two decision comparators to generate the above and below null signal and the dead band at the null signal.
From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the invention.
Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative of applications of the principles of this invention, and not in a limiting sense.
