WO2012031794A1 - Control method for a power drill and a power drill with load control means - Google Patents
Control method for a power drill and a power drill with load control means Download PDFInfo
- Publication number
- WO2012031794A1 WO2012031794A1 PCT/EP2011/060965 EP2011060965W WO2012031794A1 WO 2012031794 A1 WO2012031794 A1 WO 2012031794A1 EP 2011060965 W EP2011060965 W EP 2011060965W WO 2012031794 A1 WO2012031794 A1 WO 2012031794A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- drill
- load
- drill spindle
- spindle
- power
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q11/00—Accessories fitted to machine tools for keeping tools or parts of the machine in good working condition or for cooling work; Safety devices specially combined with or arranged in, or specially adapted for use in connection with, machine tools
- B23Q11/04—Arrangements preventing overload of tools, e.g. restricting load
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q5/00—Driving or feeding mechanisms; Control arrangements therefor
- B23Q5/22—Feeding members carrying tools or work
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q5/00—Driving or feeding mechanisms; Control arrangements therefor
- B23Q5/54—Arrangements or details not restricted to group B23Q5/02 or group B23Q5/22 respectively, e.g. control handles
- B23Q5/58—Safety devices
Definitions
- the invention relates to control method for a power drill and a power drill of the type having a drill spindle carrying a drill bit, a rotation motor, and a power
- the invention concerns the type of power drill wherein the power transmission comprises a load limiting means for protecting the object being drilled, the drill bit, and other parts of the power drill from
- Such excessive drilling resistance may occur due to a number of reasons, for instance a worn down or broken drill bit, and a clogging up of drillings in the hole being drilled.
- some prior art power drills have control systems for accomplishing a so called peck drilling, which means that the drilling operation is proceeded in a number of steps such that the drill spindle is repeatedly
- load limiting means in the form of break pins to be sheared off at excessive load, or different kinds of overload release clutches. In both cases the drilling operation is
- an production stop may be caused by to a stuck drill bit, and the drill bit and drill spindle have to be removed from the work piece and
- the release clutch also needs to be reset.
- the invention intends to solve the above described problems and drawbacks of prior art power drills.
- Fig. 1 shows, partly in section, a side view of a power drill according to the invention.
- Fig. 2 shows, on a larger scale, a longitudinal section through a portion of the power drill in Fig. 1.
- a housing 10 supporting a drill spindle 11, a power transmission 12, and a pneumatic rotation motor 13.
- a connection socket 15 for receiving a connection plug of a pressure air supply line, and a throttle valve operable by a push button 16.
- the drill spindle 11 is rotatable as well as longitudinally moveable by means of the power
- an operation control unit 17 for controlling the motor and power transmission operation to thereby control the rotational and longitudinal
- the control unit 17 comprises a number of pneumatic components activated via signals from a load indicating device 18 and arranged to control the drill spindle displacement shifting means.
- the load indicating device 18 is described in further detail below .
- the rear end of the drill spindle 11 is covered by a tubular sleeve element 19, and the forward end of the spindle 11 is provided with a chuck 20 for connection of a non-illustrated drilling implement like a drill bit.
- the motor 13 is drivingly connected to the power
- the clutch 26 comprises a driving clutch half 27 rotationally locked but longitudinally displaceable relative to the first part 23 of the drive spindle 22, and a driven clutch half 28 rigidly connected to the second part 24 of the drive spindle 22.
- Both of the driving and driven clutch halves 27 and 28 are provided with axially directed teeth 30 and 31, respectively.
- Belleville-type washer springs is supported between a shoulder 33 on the first part 23 of the drive spindle 22 and the driving clutch half 27.
- the teeth 30,31 are formed with interacting slanted shoulders to form a camming means which will cause the clutch halves 27, 28 to rotate
- the driving clutch half 27 is provided with a conical surface 36, and a pointed sensing rod 37 of the load indicating device 18 is arranged to be engaged by the conical surface 36 and pushed outwardly as the driving clutch half 27 starts moving axially at a certain
- the load indicating device 18 further comprises a ball type valve 39 by which a connection between a pressurized passage 40 communicating with the control unit 17 and a drain passage 41 is
- the valve 39 comprises a valve ball 44 movably supported in a valve chamber 45 and sealingly co-operating with a seat 46.
- a spring 48 is supported between the valve ball 44 and a firmly secured second ball 47 in the valve chamber 45 to exert a closing force on the valve ball 44 and simultaneously a reset force on the sensing rod 37.
- the control passage 40 communicates with the control unit 17, and when a predetermined torque is reached on the drive spindle 22 the clutch halves 27, 28 starts separating, and the valve ball 47 is lifted off the seat 46 by the sensing rod 37 to open up a communication between the pressurized control passage 40 and the drain passage 41. Thereby a negative control signal is sent the control unit 17 as the passage 41 is depressurized through the valve 39. This signal makes the control unit 17 shift the operation mode of the drill spindle 11, such that the forward feed
- load indication that includes the total load on the drill spindle, i.e. both the torque resistance and the applied feed force.
- the drill unit may be electrically powered, wherein the control system would comprise electric components instead of pneumatic components and the load indicating device on the drive spindle may be of an electric torque transducer type .
Abstract
A control method for a power drill and a power drill relating to the type of power drill having a rotatable and longitudinally displaceable drill spindle (11)and carrying a drilling implement, a power transmission (12) coupling a rotation motor (13) to the drill spindle (11), and a control unit (17) for controlling the operation of the drill spindle (11), wherein the power transmission (12) includes an indicating device(38)for indicating a load magnitude corresponding to the total load transferred by the drill spindle (11) during drilling. An activating device (26) is arranged to activate the indicating device (38) as the load transferred by the drill spindle (11) reaches a predetermined level to thereby accomplish a shifting of the drill spindle operation from a forward directed feeding movement to a reverse retract movement, whereby the drilling implement and/or the object being drilled are prevented from being damaged.
Description
Control method for a power drill and a power drill with load control means.
The invention relates to control method for a power drill and a power drill of the type having a drill spindle carrying a drill bit, a rotation motor, and a power
transmission for coupling the motor to the drill spindle and for applying a rotational movement as well as a
longitudinal feed movement on the drill spindle.
In particular, the invention concerns the type of power drill wherein the power transmission comprises a load limiting means for protecting the object being drilled, the drill bit, and other parts of the power drill from
undesirable strain at excessive drilling resistance. Such excessive drilling resistance may occur due to a number of reasons, for instance a worn down or broken drill bit, and a clogging up of drillings in the hole being drilled. As to the latter problem some prior art power drills have control systems for accomplishing a so called peck drilling, which means that the drilling operation is proceeded in a number of steps such that the drill spindle is repeatedly
retracted from the hole being drilled to lift out produced drillings. This is accomplished at certain predetermined points during the drilling operation notwithstanding any increased drilling resistance.
In some previous power drills there have been employed load limiting means in the form of break pins to be sheared off at excessive load, or different kinds of overload release clutches. In both cases the drilling operation is
interrupted at overload, and in at least in the break pin arrangement the power drill has to be taken out of
production and dismantled to fit a new break pin. Also in the release clutch cases an production stop may be caused by to a stuck drill bit, and the drill bit and drill spindle have to be removed from the work piece and
reinstalled drill for continued drilling operation.
Usually, the release clutch also needs to be reset.
Since there is a time consuming and expensive procedure to remove, dismantle and reinstall the power drill after an overload break pin breakage or clutch release the maximum load limit for such a production stop is set rather high to avoid too many production stops. This high load limit causes another problem, namely an impaired quality of the drilled hole, because a worn down or damaged drill bit or a clogging up by drillings very often cause damages to the hole being drilled. This means that in such cases the hole has to be enlarged to a bigger diameter to cure such damages and to obtain a drilled hole with the desired finish .
A power drill similar to the above type is described in for instance US Patent No. 4,591,299. However, this known power drill has no means for indicating the transferred torque load on the drill spindle, and hence no means for
automatically stopping an ongoing drilling operation and retract the drill spindle for inspection of the drill bit.
The invention intends to solve the above described problems and drawbacks of prior art power drills.
It is an object of the invention to provide a method by which the operation of a power drill of the above described
type is controlled to avoid the problems and drawbacks encountered at operation of prior art drills.
It is a further object of the invention to provide an improved power drill of the initially described type having means for controlling the drilling operation in response to the encountered load magnitude on the drill spindle, thereby avoiding problems and drawbacks of prior art power drills .
Further objects and advantages of the invention will appear from the following specification and claims.
A preferred embodiment of the invention is described below with reference to the accompanying drawings.
In the drawings
Fig. 1 shows, partly in section, a side view of a power drill according to the invention.
Fig. 2 shows, on a larger scale, a longitudinal section through a portion of the power drill in Fig. 1.
The power drill illustrated in the drawing figures
comprises a housing 10 supporting a drill spindle 11, a power transmission 12, and a pneumatic rotation motor 13. At the rear end of the housing 10 there is provided a connection socket 15 for receiving a connection plug of a pressure air supply line, and a throttle valve operable by a push button 16. The drill spindle 11 is rotatable as well as longitudinally moveable by means of the power
transmission 12 in a forward directed feed movement during drilling and a rearward directed retract movement at completed or discontinued drilling operations. To the
housing 10 there is attached an operation control unit 17 for controlling the motor and power transmission operation to thereby control the rotational and longitudinal
movements of the drill spindle 11. The control unit 17 comprises a number of pneumatic components activated via signals from a load indicating device 18 and arranged to control the drill spindle displacement shifting means. The load indicating device 18 is described in further detail below .
The rear end of the drill spindle 11 is covered by a tubular sleeve element 19, and the forward end of the spindle 11 is provided with a chuck 20 for connection of a non-illustrated drilling implement like a drill bit.
The motor 13 is drivingly connected to the power
transmission 12 via a drive spindle 22. The latter
comprises two parts, namely a first part 23 connected to the motor 13, and a second part 24 connected to a driving element 25 of the power transmission 12. The first and second parts 23 and 24, respectively, are rotatively supported relative to each other, but a cam type torque responsive cam type clutch 26 is arranged to transfer torque between the two spindle parts 23,24. The clutch 26 comprises a driving clutch half 27 rotationally locked but longitudinally displaceable relative to the first part 23 of the drive spindle 22, and a driven clutch half 28 rigidly connected to the second part 24 of the drive spindle 22. Both of the driving and driven clutch halves 27 and 28 are provided with axially directed teeth 30 and 31, respectively. A spring 32 in the form of a pile of
Belleville-type washer springs is supported between a shoulder 33 on the first part 23 of the drive spindle 22
and the driving clutch half 27. The teeth 30,31 are formed with interacting slanted shoulders to form a camming means which will cause the clutch halves 27, 28 to rotate
relative to each other and separate axially against the action of the spring 32 at a certain torque load applied on the drive spindle 22. Then the driving clutch half 27 will move axially.
The driving clutch half 27 is provided with a conical surface 36, and a pointed sensing rod 37 of the load indicating device 18 is arranged to be engaged by the conical surface 36 and pushed outwardly as the driving clutch half 27 starts moving axially at a certain
predetermined transferred torque level. The load indicating device 18 further comprises a ball type valve 39 by which a connection between a pressurized passage 40 communicating with the control unit 17 and a drain passage 41 is
controlled. The valve 39 comprises a valve ball 44 movably supported in a valve chamber 45 and sealingly co-operating with a seat 46. A spring 48 is supported between the valve ball 44 and a firmly secured second ball 47 in the valve chamber 45 to exert a closing force on the valve ball 44 and simultaneously a reset force on the sensing rod 37.
The control passage 40 communicates with the control unit 17, and when a predetermined torque is reached on the drive spindle 22 the clutch halves 27, 28 starts separating, and the valve ball 47 is lifted off the seat 46 by the sensing rod 37 to open up a communication between the pressurized control passage 40 and the drain passage 41. Thereby a negative control signal is sent the control unit 17 as the passage 41 is depressurized through the valve 39. This signal makes the control unit 17 shift the operation mode
of the drill spindle 11, such that the forward feed
movement of the drill spindle 11 is shifted to a rearward retract movement. Then, the torque load on the power transmission 12 is discontinued or at least substantially reduced, and overload related damages on the drilling implement and/or the object being drilled are avoided.
By arranging the load indicating device on the drive spindle 22 which connects the motor to the power
transmission 12 there is obtained load indication that includes the total load on the drill spindle, i.e. both the torque resistance and the applied feed force.
It is to be noted that the invention is not limited to the described example but may be freely varied within the scope of the claims. For instance, the load indicating device could be of a different kind. Instead of a torque
responsive mechanical clutch and a movement sensing means coupled to the clutch as described above there may be used other types of commercially available torque sensing means for indicating the load level on the drill spindle. Also, the drill unit may be electrically powered, wherein the control system would comprise electric components instead of pneumatic components and the load indicating device on the drive spindle may be of an electric torque transducer type .
Claims
1. Method for controlling the operation of a power drill having a rotatable and longitudinally displaceable drill spindle, comprising the following steps:
• starting a drilling operation by rotating and
displacing the drill spindle in a forward feed
movement,
• indicating during the drilling operation the magnitude of the load transferred by the drill spindle,
• comparing continuously during the drilling operation the indicated load magnitude with a pre-set maximum load magnitude,
• shifting automatically the displacement of the drill spindle from the forward feed movement to a reverse retract movement as the load magnitude transferred by the drill spindle reaches said pre-set maximum load magnitude, and
• stopping the drilling operation as the drill spindle reaches a fully retracted position.
2. Method according to claim 1, including reassuming the drilling operation by rotating and displacing the drill spindle in a forward feed movement after checking and/or replacing the drilling implement.
3. Method according to claim 2, wherein the drilling operation is reassumed by manual trigging.
4. Power drill comprising a rotation motor (13), a drill spindle (11) carrying a drilling implement and being rotatable and longitudinally displaceable in a forward feed movement and a reverse retract movement, a power transmission (12) coupling the motor (13) to the drill spindle (11), and a control unit (17) controlling the rotational movement as well as the longitudinal
displacement of the drill spindle (11),
c h a r a c t e r i z e d in that
• the control system (12) comprises a load indicating device (18),
• an activating device (36, 37) is arranged to activate said load indicating device (18) in response to the load magnitude transferred by the drill spindle (11),
• a means (30) is employed for determining a maximum
load magnitude at which said activating device (36,37) starts activating said load indicating device (18), and
• a drill spindle displacement shifting means is
arranged to be activated by the control unit (17) and by signals from said load indicating device (18) shifting the operation of said drill spindle (11) from a forward feed movement to a reverse retract movement as said load indicating device indicates that the load magnitude transferred by the drill spindle (11) has reached said maximum load magnitude.
5. Power drill according to claim 4, wherein said load indicating device (18) is disposed on a drive spindle (22) connected the motor (13) to said power transmission (12) .
6. Power drill according to claim 4 and 5, wherein said load indicating device (18) comprises a mechanical cam clutch (26) disposed on said drive spindle (22) and having an axially movable part (27), and said means for
determining the maximum transferred load comprises a spring means acting on said movable part (27) and arranged to let said movable part (27) be displaced at load magnitudes above said maximum load magnitude only, and said activating device (18) is arranged to be activated by said movable part (28) and to activate said drill spindle movement shifting means at displacement of said movable part (28) .
7. Power drill according to claim 6, wherein said activating device (18) comprises a displaceable element (37) arranged to be shifted by said movable part (27) between a rest position and an activated position.
8. Power drill according to anyone of claims 4-7, wherein the motor unit (13) and the control unit (17) are pneumatically powered, and said activating device (18) comprises a pneumatic valve (39) including said
displaceable element (37) and shiftable between an open position and a closed position.
9. Power drill according to claim 4, wherein the motor is an electric motor, and the control system
comprises electric components, and said load indicating device comprises a torque transducer incorporated in the power transmission and arranged to generate electrical signals corresponding to the actual load magnitude
transferred by the drill spindle.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1050929 | 2010-09-09 | ||
| SE1050929-7 | 2010-09-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2012031794A1 true WO2012031794A1 (en) | 2012-03-15 |
Family
ID=44628343
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP2011/060965 WO2012031794A1 (en) | 2010-09-09 | 2011-06-29 | Control method for a power drill and a power drill with load control means |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO2012031794A1 (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2807176A (en) * | 1952-03-07 | 1957-09-24 | Bellows Company | Automatic drill feed |
| US4591299A (en) | 1984-05-21 | 1986-05-27 | Dresser Industries, Inc. | Rapid feed apparatus for automatic feed drills or the like |
| WO2000078502A2 (en) * | 1999-06-18 | 2000-12-28 | Cooper Technologies Company | Positive feed tool having retractable members |
| WO2000078490A2 (en) * | 1999-06-18 | 2000-12-28 | Cooper Technologies Company | Positive feed tool having a clutch |
| EP1852201A2 (en) * | 2006-05-05 | 2007-11-07 | Metabowerke GmbH & Co. | Drilling device, in particular a hammer drill |
-
2011
- 2011-06-29 WO PCT/EP2011/060965 patent/WO2012031794A1/en active Application Filing
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2807176A (en) * | 1952-03-07 | 1957-09-24 | Bellows Company | Automatic drill feed |
| US4591299A (en) | 1984-05-21 | 1986-05-27 | Dresser Industries, Inc. | Rapid feed apparatus for automatic feed drills or the like |
| WO2000078502A2 (en) * | 1999-06-18 | 2000-12-28 | Cooper Technologies Company | Positive feed tool having retractable members |
| WO2000078490A2 (en) * | 1999-06-18 | 2000-12-28 | Cooper Technologies Company | Positive feed tool having a clutch |
| EP1852201A2 (en) * | 2006-05-05 | 2007-11-07 | Metabowerke GmbH & Co. | Drilling device, in particular a hammer drill |
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