US20030064670A1 - Worktool - Google Patents
Worktool Download PDFInfo
- Publication number
- US20030064670A1 US20030064670A1 US10/259,533 US25953302A US2003064670A1 US 20030064670 A1 US20030064670 A1 US 20030064670A1 US 25953302 A US25953302 A US 25953302A US 2003064670 A1 US2003064670 A1 US 2003064670A1
- Authority
- US
- United States
- Prior art keywords
- worktool
- axis
- planetary gears
- drive shaft
- carriage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B7/00—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor
- B24B7/10—Single-purpose machines or devices
- B24B7/18—Single-purpose machines or devices for grinding floorings, walls, ceilings or the like
- B24B7/186—Single-purpose machines or devices for grinding floorings, walls, ceilings or the like with disc-type tools
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B23/00—Portable grinding machines, e.g. hand-guided; Accessories therefor
- B24B23/02—Portable grinding machines, e.g. hand-guided; Accessories therefor with rotating grinding tools; Accessories therefor
- B24B23/03—Portable grinding machines, e.g. hand-guided; Accessories therefor with rotating grinding tools; Accessories therefor the tool being driven in a combined movement
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B41/00—Component parts such as frames, beds, carriages, headstocks
- B24B41/04—Headstocks; Working-spindles; Features relating thereto
- B24B41/047—Grinding heads for working on plane surfaces
Definitions
- This invention relates to worktools and, in particular, rotating worktools that engage with a surface, such as sanders and polishing machines.
- Known orbital and random-orbital worktools such as sanders, function by driving an abrasive surface in a circular path about principal drive shaft.
- a surface may be of fixed orientation or free to rotate about an eccentric axis, according to whether the resulting motion is required to be orbital, or random-orbital respectively.
- Such work tools suffer from vibration. Vibration in such systems has two distinct components, dynamic (which results from unbalanced centripetal acceleration) and frictional (which results from the translating frictional forces between the working surface of the tool and the work piece).
- Dynamic imbalance can normally be corrected by distributing counter weights at particular axial, radial and phase positions on the drive axis of the worktool.
- this approach relies on the working surface of the tool, such as the sanding platen, and any attached replacement component being of constant mass. This means that changing the platen or replacing the working material can often cause unwanted vibration.
- Vibration experienced in use also often arises from translating frictional forces between the abrasive surface, acting so as to make the eccentric drive axis the centre of rotation. In the worst case, these vibrations can be of an amplitude equal to the shaft eccentricity, in the case that the principal drive shaft orbits the stationary eccentric shaft.
- Frictional vibration increases with increasing contact force, resulting in a reduction of sanding efficiency that tends to zero as the amplitude of vibration tends to the eccentricity of the drive axis.
- a common misconception is that by increasing the contact force an increase in material removal rate can be achieved.
- counter-intuitive system behaviour in prior-art solutions often results in poor sanding efficiency, and high levels of vibration. It is the aim of the present invention to markedly reduce vibration arising from translating frictional forces, by ensuring that such forces are reacted within a system of sanding surfaces, thereby increasing the sanding efficiency and rate of material removal that can be achieved.
- a worktool comprising: a principal drive shaft with a sun gear attached thereto; at least two planetary gears distributed about the circumference of the sun gear at substantially equal angular separation; and a carriage for constraining the planetary gears such that they maintain their angular separation about the axis of the principal drive shaft, wherein: each planetary gear has an eccentric axis in addition to its rotational axis constrained by the carriage, such that each planetary gear can drive, in use, a platen around the respective eccentric axis.
- the platens may be freely rotating, or partially constrained from rotating with respect to the carriage thereby fixing the orientation of the platens with respect to one another. Partially constraining the platens in this way permits the use of tessellating platen configurations.
- the worktool may be a sander or a polisher.
- the principal drive shaft may be connected, optionally through an additional gear mechanism, to an electric motor.
- the eccentric axes In order to preserve the dynamic balance of the system, and to ensure that the frictional forces that might cause vibration are mutually resolved, the eccentric axes have a particular phase relationship.
- the phase difference between any two eccentric axes may be chosen to be 2 ⁇ /n radians, wherein n equals the number of planetary gears and is an integer value greater than 1. This relationship ensures that the centre of mass of the combined system does not depart from the principal axis of rotation.
- the arrangement of sanding elements is dynamically balanced, removing the need for the system of counterweights common in conventional sanders.
- the sanding platens and abrasive surfaces can also be replaced without unduly compromising the dynamic balance.
- the present invention can be configured to be operable in a number of modes, optimising the motion for a given sanding operation or spatial constraint.
- FIGS. 1 and 2 are isometric and plan views of a work tool according to the present invention.
- FIG. 3 is a plan view of a device according to the present invention, with an additional gear shown.
- FIG. 4 is a plan view showing alternative configurations of the platens only.
- FIGS. 1 and 2 there is shown a principal drive shaft 1 and carriage 4 , of a worktool, such as a sander, to which a sun gear 2 is attached.
- a number of planetary gears 3 are distributed about the circumference of the sun gear 2 at equal angular separation.
- the planetary gears 3 are constrained by a carriage 4 , locating the centres and maintaining the angular separation about the principal axis of the drive shaft 1 .
- Each planetary gear 3 has an eccentric axis 5 , in addition to the centre of rotation constrained by the carriage 4 , driving a freely rotating or partially rotationally constrained platen 6 .
- each of the platens 8 or 9 can be attached to a respective eccentric axis 5 , instead of the circular platen 6 shown in FIG. 1.
- a square platen 10 can be attached to each of the respective eccentric axes 5 .
- the platens 6 will orbit a fixed centre, with no bulk rotation of the combined system. This constitutes a mode of operation suitable for sanding an inside corner that would be inaccessible by an equivalent single sanding platen of an area equal to the sum of the platen areas.
- FIG. 3 shows an optimal additional gear 7 composed inwardly facing teeth with engage with each of the planetary gears and is concentric with the principal drive axis 1 .
- this additional gear 7 is free to rotate, the above modes are accessible.
- the platen centres will be driven in a strictly epicyclic motion. This would result in higher surface to surface speeds, and a corresponding increase in the rate of material removal.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
Abstract
A worktool comprises a principal drive shaft with a sun gear attached thereto. At least two planetary gears are distributed about the circumference of the sun gear at substantially equal angular separation. A carriage constrains the planetary gears such that they maintain their angular separation about the axis of the principal drive shaft. Each planetary gear has an eccentric axis in addition to its rotational axis constrained by the carriage, such that each planetary gear can drive, in use, a rotating work-piece engaging surface around the respective eccentric axis. There may be a phase difference of 2π/n radians (n being an integer equal to the number of planetary gears) between any two eccentric axes.
Description
- This invention relates to worktools and, in particular, rotating worktools that engage with a surface, such as sanders and polishing machines.
- Known orbital and random-orbital worktools, such as sanders, function by driving an abrasive surface in a circular path about principal drive shaft. A surface may be of fixed orientation or free to rotate about an eccentric axis, according to whether the resulting motion is required to be orbital, or random-orbital respectively. Such work tools suffer from vibration. Vibration in such systems has two distinct components, dynamic (which results from unbalanced centripetal acceleration) and frictional (which results from the translating frictional forces between the working surface of the tool and the work piece).
- Dynamic imbalance can normally be corrected by distributing counter weights at particular axial, radial and phase positions on the drive axis of the worktool. However, this approach relies on the working surface of the tool, such as the sanding platen, and any attached replacement component being of constant mass. This means that changing the platen or replacing the working material can often cause unwanted vibration.
- Vibration experienced in use also often arises from translating frictional forces between the abrasive surface, acting so as to make the eccentric drive axis the centre of rotation. In the worst case, these vibrations can be of an amplitude equal to the shaft eccentricity, in the case that the principal drive shaft orbits the stationary eccentric shaft.
- Frictional vibration increases with increasing contact force, resulting in a reduction of sanding efficiency that tends to zero as the amplitude of vibration tends to the eccentricity of the drive axis. A common misconception is that by increasing the contact force an increase in material removal rate can be achieved. As such, counter-intuitive system behaviour in prior-art solutions often results in poor sanding efficiency, and high levels of vibration. It is the aim of the present invention to markedly reduce vibration arising from translating frictional forces, by ensuring that such forces are reacted within a system of sanding surfaces, thereby increasing the sanding efficiency and rate of material removal that can be achieved.
- According to the present invention there is provided a worktool comprising: a principal drive shaft with a sun gear attached thereto; at least two planetary gears distributed about the circumference of the sun gear at substantially equal angular separation; and a carriage for constraining the planetary gears such that they maintain their angular separation about the axis of the principal drive shaft, wherein: each planetary gear has an eccentric axis in addition to its rotational axis constrained by the carriage, such that each planetary gear can drive, in use, a platen around the respective eccentric axis.
- The platens may be freely rotating, or partially constrained from rotating with respect to the carriage thereby fixing the orientation of the platens with respect to one another. Partially constraining the platens in this way permits the use of tessellating platen configurations.
- The worktool may be a sander or a polisher. The principal drive shaft may be connected, optionally through an additional gear mechanism, to an electric motor.
- In order to preserve the dynamic balance of the system, and to ensure that the frictional forces that might cause vibration are mutually resolved, the eccentric axes have a particular phase relationship. The phase difference between any two eccentric axes may be chosen to be 2π/n radians, wherein n equals the number of planetary gears and is an integer value greater than 1. This relationship ensures that the centre of mass of the combined system does not depart from the principal axis of rotation.
- With the invention, since the translating frictional forces are mutually reacted, vibration transmitted to the user is in principle decoupled from the applied contact force. Similarly, sanding efficiency is not unduly compromised by increasing contact force, permitting higher rates of material removal. This aspect of the present invention compliments user-intuition, unlike the prior art systems described above.
- Furthermore, the arrangement of sanding elements is dynamically balanced, removing the need for the system of counterweights common in conventional sanders. The sanding platens and abrasive surfaces can also be replaced without unduly compromising the dynamic balance.
- The present invention can be configured to be operable in a number of modes, optimising the motion for a given sanding operation or spatial constraint.
- An example of the present invention will now be described with reference to the accompanying drawings, in which:
- FIGS. 1 and 2 are isometric and plan views of a work tool according to the present invention.
- FIG. 3 is a plan view of a device according to the present invention, with an additional gear shown.
- FIG. 4 is a plan view showing alternative configurations of the platens only.
- Referring first to FIGS. 1 and 2, there is shown a
principal drive shaft 1 andcarriage 4, of a worktool, such as a sander, to which asun gear 2 is attached. A number ofplanetary gears 3 are distributed about the circumference of thesun gear 2 at equal angular separation. Theplanetary gears 3 are constrained by acarriage 4, locating the centres and maintaining the angular separation about the principal axis of thedrive shaft 1. Eachplanetary gear 3 has aneccentric axis 5, in addition to the centre of rotation constrained by thecarriage 4, driving a freely rotating or partially rotationally constrainedplaten 6. - If the platens are partially constrained from rotating then alternative tessellating platen configurations are possible. Some examples of such configurations are shown in FIG. 4. With reference to FIG. 4, each of the
platens eccentric axis 5, instead of thecircular platen 6 shown in FIG. 1. Alternatively, in an embodiment that employs fourplanetary gears 3, asquare platen 10 can be attached to each of the respectiveeccentric axes 5. - When free to rotate the
carriage 4 will be driven by a net torque between the sanding surfaces and the work-piece (not shown) causing the sanding centres to describe a distorted epicycloid where the number of rotations of the respective planetary gear is not purely a function of the sun/planetary gear ratio. This is a random motion most suited to finishing applications. - If the
carriage 4 is prevented from rotating, preferably with a user-engaged lock, theplatens 6 will orbit a fixed centre, with no bulk rotation of the combined system. This constitutes a mode of operation suitable for sanding an inside corner that would be inaccessible by an equivalent single sanding platen of an area equal to the sum of the platen areas. - FIG. 3 shows an optimal
additional gear 7 composed inwardly facing teeth with engage with each of the planetary gears and is concentric with theprincipal drive axis 1. When thisadditional gear 7 is free to rotate, the above modes are accessible. However, when prevented from rotating, again with a user-engaged lock, the platen centres will be driven in a strictly epicyclic motion. This would result in higher surface to surface speeds, and a corresponding increase in the rate of material removal.
Claims (8)
1. A worktool comprising:
a principal drive shaft with a sun gear attached thereto;
at least two planetary gears distributed about the circumference of the sun gear at substantially equal angular separation; and
a carriage for constraining the planetary gears such that they maintain their angular separation about the axis of the principal drive shaft,
wherein:
each planetary gear has an eccentric axis in addition to its rotational axis constrained by the carriage, such that each planetary gear can drive, in use, a platen around the respective eccentric axis.
2. The worktool of claim 1 , wherein the phase difference between any two eccentric axes is to be 2π/n radians, wherein n equals the number of planetary gears and is an integer value greater than 1.
3. The worktool of claim 1 , arranged to be a polisher.
4. The worktool of claim 1 , arranged to be a sander.
5. The worktool of claim 1 , wherein the principal drive shaft is connected to a motor.
6. The worktool of claim 1 , wherein the platens can rotate freely.
7. The worktool of claim 1 , wherein the platens are partially rotationally constrained.
8. A worktool comprising:
a principal drive shaft with a sun gear attached thereto;
at least two planetary gears distributed about the circumference of the sun gear at substantially equal angular separation; and
a carriage for constraining the planetary gears such that they maintain their angular separation about the axis of the principal drive shaft,
wherein:
each planetary gear has an eccentric axis in addition to its rotational axis constrained by the carriage, such that each planetary gear can drive, in use, a platen around the respective eccentric axis, and wherein the phase difference between any two eccentric axes is to be 2π/n radians, wherein n equals the number of planetary gears and is an integer value greater than 1.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0123657.9 | 2001-10-02 | ||
GBGB0123657.9A GB0123657D0 (en) | 2001-10-02 | 2001-10-02 | Worktool |
Publications (1)
Publication Number | Publication Date |
---|---|
US20030064670A1 true US20030064670A1 (en) | 2003-04-03 |
Family
ID=9923108
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/259,533 Abandoned US20030064670A1 (en) | 2001-10-02 | 2002-09-30 | Worktool |
Country Status (3)
Country | Link |
---|---|
US (1) | US20030064670A1 (en) |
EP (1) | EP1300218A1 (en) |
GB (1) | GB0123657D0 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040082285A1 (en) * | 2002-01-08 | 2004-04-29 | Daniel Bohler | Device for the treatment/working of surfaces |
EP1466698A1 (en) * | 2003-04-09 | 2004-10-13 | Günther Böhler GmbH | Surface treatment device |
US20080038510A1 (en) * | 2004-09-02 | 2008-02-14 | Inoplast | Plastic Material That Can Be Used, in Particular, for Producing Motor Vehicle Floor Pans, and Motor Vehicle Floor Pan Made With Such a Material |
CN100460154C (en) * | 2005-05-24 | 2009-02-11 | 蔡墩军 | Bi-three-jaw shaped contrarotating planetary grinding head |
CN107855886A (en) * | 2017-11-02 | 2018-03-30 | 广东工科机电有限公司 | Dry type flexible grinding and polishing method and its supporting cutter, equipment |
CN108789111A (en) * | 2018-08-14 | 2018-11-13 | 天长市永鑫制冷设备有限公司 | Simple type burnishing device |
CN113490573A (en) * | 2018-12-27 | 2021-10-08 | 罗伯特·博世有限公司 | Hand-held power tool |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2399615B (en) * | 2003-03-21 | 2006-03-15 | Black & Decker Inc | Vibration reduction apparatus for power tool and power tool incorporating such apparatus |
AU2003219306A1 (en) * | 2003-03-28 | 2004-10-18 | The Technology Partnership Plc | Rotary work tool with orbiting planetary gears containing eccentric axes for the attachment of polishing or sanding platens |
ITVI20040090A1 (en) | 2004-04-16 | 2004-07-16 | Positec Group Ltd | ANTI-VIBRATION DEVICE FOR MOTORIZED SANDING MACHINE, AND INCORPORATING SANDING MACHINE SUCH AS DEVICE |
US7104873B1 (en) | 2005-04-18 | 2006-09-12 | Positec Power Tools (Suzhou) Co. | Anti-vibration arrangement |
WO2007000074A1 (en) * | 2005-06-27 | 2007-01-04 | Positec Power Tools (Suzhou) Co., Ltd. | Anti-vibration device for an abrasive machine, a machine having such device and a method for cleaning the surface of a work piece |
CN109366100A (en) * | 2018-10-31 | 2019-02-22 | 南京新尼亚文汽车零部件有限公司 | It is a kind of efficiently to produce mechanism convenient for the integrated platen of operation |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US757053A (en) * | 1903-09-03 | 1904-04-12 | Claude Louis Rameau | Machine for grinding lenses. |
US2668968A (en) * | 1949-01-05 | 1954-02-16 | Joseph M Dobrowolski | Meat block scrubber |
US3631635A (en) * | 1969-11-07 | 1972-01-04 | Kenneth W Vezner | Grinding and polishing machine |
US3886689A (en) * | 1972-10-05 | 1975-06-03 | Toyo Kogyo Co | Apparatus for forming a trochoidal surface |
US4709510A (en) * | 1985-01-22 | 1987-12-01 | Todescato Giovanni | Floor sanding and polishing machine |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CH237159A (en) * | 1943-08-19 | 1945-04-15 | Buehler Ag Geb | Floor cleaning device. |
CH268486A (en) * | 1948-09-25 | 1950-05-31 | Mueller Bruetsch & Co | Machine for cleaning floors. |
US2759305A (en) * | 1954-06-11 | 1956-08-21 | Cyclo Mfg Company | Portable abrading and polishing machine |
DE1158674B (en) * | 1959-07-29 | 1963-12-05 | Mauz & Pfeiffer | Multi-disc polisher |
US4097950A (en) * | 1977-03-07 | 1978-07-04 | Milliken Research Corporation | Device for scrubbing surfaces |
-
2001
- 2001-10-02 GB GBGB0123657.9A patent/GB0123657D0/en not_active Ceased
-
2002
- 2002-09-30 US US10/259,533 patent/US20030064670A1/en not_active Abandoned
- 2002-10-02 EP EP02256865A patent/EP1300218A1/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US757053A (en) * | 1903-09-03 | 1904-04-12 | Claude Louis Rameau | Machine for grinding lenses. |
US2668968A (en) * | 1949-01-05 | 1954-02-16 | Joseph M Dobrowolski | Meat block scrubber |
US3631635A (en) * | 1969-11-07 | 1972-01-04 | Kenneth W Vezner | Grinding and polishing machine |
US3886689A (en) * | 1972-10-05 | 1975-06-03 | Toyo Kogyo Co | Apparatus for forming a trochoidal surface |
US4709510A (en) * | 1985-01-22 | 1987-12-01 | Todescato Giovanni | Floor sanding and polishing machine |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040082285A1 (en) * | 2002-01-08 | 2004-04-29 | Daniel Bohler | Device for the treatment/working of surfaces |
EP1466698A1 (en) * | 2003-04-09 | 2004-10-13 | Günther Böhler GmbH | Surface treatment device |
US20080038510A1 (en) * | 2004-09-02 | 2008-02-14 | Inoplast | Plastic Material That Can Be Used, in Particular, for Producing Motor Vehicle Floor Pans, and Motor Vehicle Floor Pan Made With Such a Material |
CN100460154C (en) * | 2005-05-24 | 2009-02-11 | 蔡墩军 | Bi-three-jaw shaped contrarotating planetary grinding head |
CN107855886A (en) * | 2017-11-02 | 2018-03-30 | 广东工科机电有限公司 | Dry type flexible grinding and polishing method and its supporting cutter, equipment |
CN108789111A (en) * | 2018-08-14 | 2018-11-13 | 天长市永鑫制冷设备有限公司 | Simple type burnishing device |
CN113490573A (en) * | 2018-12-27 | 2021-10-08 | 罗伯特·博世有限公司 | Hand-held power tool |
Also Published As
Publication number | Publication date |
---|---|
EP1300218A1 (en) | 2003-04-09 |
GB0123657D0 (en) | 2001-11-21 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: THE TECHNOLOGY PARTNERSHIP PLC, UNITED KINGDOM Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CARR, MATTHEW;REEL/FRAME:013686/0858 Effective date: 20020903 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |