GB2425978A - A process for operating an electrically driven machine tool - Google Patents

A process for operating an electrically driven machine tool Download PDF

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Publication number
GB2425978A
GB2425978A GB0608611A GB0608611A GB2425978A GB 2425978 A GB2425978 A GB 2425978A GB 0608611 A GB0608611 A GB 0608611A GB 0608611 A GB0608611 A GB 0608611A GB 2425978 A GB2425978 A GB 2425978A
Authority
GB
United Kingdom
Prior art keywords
high frequency
machine tool
voltage
frequency converter
electrically driven
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.)
Granted
Application number
GB0608611A
Other versions
GB0608611D0 (en
GB2425978B (en
Inventor
Mike Voigt
Gerhard Sanwald
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of GB0608611D0 publication Critical patent/GB0608611D0/en
Publication of GB2425978A publication Critical patent/GB2425978A/en
Application granted granted Critical
Publication of GB2425978B publication Critical patent/GB2425978B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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
    • B23Q15/00—Automatic control or regulation of feed movement, cutting velocity or position of tool or work
    • B23Q15/007—Automatic control or regulation of feed movement, cutting velocity or position of tool or work while the tool acts upon the workpiece
    • B23Q15/12—Adaptive control, i.e. adjusting itself to have a performance which is optimum according to a preassigned criterion
    • 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
    • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
    • B24B49/10—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving electrical means
    • 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
    • B24B55/00—Safety devices for grinding or polishing machines; Accessories fitted to grinding or polishing machines for keeping tools or parts of the machine in good working condition
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • General Induction Heating (AREA)

Abstract

A process for operating an electrically driven machine tool having a high frequency converter, which high frequency converter actuates an electric motor at high frequency, where an output voltage (U) and/or a frequency (f) of the high frequency converter are adjusted depending on a load in an operating state of the electrically driven machine tool. Preferably the voltage is lowered at a constant frequency if the load is reduced or the machine tool is in an idle state. A voltage and/or frequency increase may be brought about when the load increases. Preferably the high frequency converter is a static high frequency converter.

Description

Process for operating an electrically driven machine tool, electronic unit
and electrically driven machine tool
Prior art
The invention relates to a process for operating an electrically driven machine tool and an electronic unit and electrically driven machine tool according to the preambles of the independent patent claims.
Static frequency converters are used with electrically driven machine tools such as grinding devices with which static frequency converters a tool is actuated at high frequency. This requires an adequate cooling capacity and a considerable ekpenditure of energy, which is reflected in manufacturing costs and operating costs.
Advantages of the invention There is proposed a process wherein an output voltage and/or a frequency of the high frequency converter is or can be adjusted depending on a load in an operating state of the electrically driven machine tool. The term operating state can be understood as an operating of the electrically driven machine tool after switching on and running up to a rated frequency and rated voltage. The operating state may be an idle or a loaded state wherein the tool is used within an operating step. Expediently the frequency converter detects the load state of the electrically driven machine tool and adjusts frequency and/or voltage.
Frequency and voltage are preferably adjusted synchronously. The rated frequency is high and lies preferably within a range such as is normal for e.g. grinding devices.
In a favourable process step, proceeding from a loaded operating state the voltage is reduced at a constant frequency if the load is reduced. A considerable energy saving can be achieved by this means. A particularly quiet running of the electrically driven machine tool can be achieved.
The voltage is preferably reduced at a constant frequency in the idle state. It is favourable in this case to lower the voltage in the idle state to at least 80%, preferably to approx. 75%, of a rated voltage. Less inherent heat is generated in the electrically driven machine tool such that a cooling capacity of a fan can be used substantially more efficiently. Up to 40% higher cooling potential can be achieved with practically the same number of revolutions per minute of the fan. On the other hand the fan can also be of a smaller design, which saves installation space and requires less energy to operate the fan.
In a favourable process step a voltage and/or frequency increase occurs when the load is increased. In this case the voltage is preferably inflated to over 100% of a rated output, preferably to around 110%. A higher operating efficiency can be achieved and thereby indirectly less waste heat per operating unit.
Alternatively or additionally the frequency can be inflated to over 100% of a rated frequency.
An electronic unit for the purpose of executing the process is proposed wherein a frequency converter is provided, which frequency converter changes its output voltage and/or frequency depending on the load. The frequency converter is preferably embodied as a static frequency converter.
An electrically driven machine tool is further proposed, particularly a grinding machine having a frequency converter, wherein an output voltage and/or frequency of the frequency converter is load dependently changeable.
The invention is suitable for all electrically driven machine tools having a static frequency converter.
Drawing Further embodiments, aspects and advantages of the invention including independently of their inclusion in the claims without limitation of their commonality arise from the following based on an exemplified embodiment of the invention illustrated in a drawing.
There follows a single figure, which shows a time dependent progression of an output voltage and a frequency of a frequency converter.
Description of the exemplified embodiment
The figure shows a time dependent progression of an effective output voltage U as a solid line and a frequency f of a high frequency converter of an electrically driven machine tool as a dotted line dependent on the time t. The rated frequency and rated voltage are at 100%.
After switching on the rated voltage and the rated frequency are reached after a run in phase 10. At the start the tool of the electrically driven machine tool is not yet in working contact with an object to be machined and in a first operating state 11 the electrically driven machine tool is in the idle state. The frequency converter detects this and lowers the output voltage U to around 75%, while the frequency f remains at 100% of its rated frequency.
In a successive operating state 12 the tool is brought into working contact with the object to be machined and the load increases. The frequency converter detects the load increase and synchronously increases the frequency f and the voltage U, e.g. to 110% of the respective rated values.
In a third operating state 13 the tool is brought away from working contact with the object to be machined and another idle phase begins. The high frequency converter detects the drop in the load and lowers the voltage U back to a value below the rated voltage, while the frequency f is lowered to its rated value.

Claims (13)

  1. Patent claims 1. Process for operating an electrically driven machine tool
    having a high frequency converter which high frequency converter actuates an electric motor at high frequency, characterised in that an output voltage (U) and/or a frequency (f) of the high frequency converter is adjusted depending on a load in an operating state of the electrically driven machine tool.
  2. 2. Process according to claim 1, characterised in that, proceeding from an operating state under load, the voltage (U) is lowered at a constant frequency (f) if the load is reduced.
  3. 3. Process according to claim 2, characterised in that in the idle state the voltage (U) is lowered at a constant frequency (f)
  4. 4. Process according to one of the preceding claims, characterised in that a voltage and/or frequency increase is brought about when the load increases.
  5. 5. Process according to claim 4, characterised in that the voltage (U) is inflated to over 100% of a rated voltage.
  6. 6. Process according to claim 4 or 5, characterised in that the frequency (f) is inflated to over 100% of a rated frequency.
  7. 7. Process according to one of the preceding claims, characterised in that the voltage (U) is lowered to at least 80% of a rated voltage in the idle state.
  8. 8. Electronic unit for executing the process according to one of the preceding claims, characterised in that a high frequency converter is provided, which high frequency converter changes its output voltage (U) and/or frequency (f) depending on the load.
  9. 9. Electronic unit according to claim 8, characterised in that the high frequency converter is embodied as a static high frequency converter.
  10. 10. Electrically driven machine tool and particularly a grinding machine having a high frequency converter, characterised in that an output voltage (U) and/or frequency (f) of the high frequency converter is load dependently changeable.
  11. 11. A process for operating an electrically driven machine tool, substantially as herein described.
  12. 12. An electronic unit for operation of an electrically driven machine tool, substantially as herein described with reference to the accompanying drawings.
  13. 13. An electrically driven machine tool comprising an electronic unit as defined in any one of claims 8, 9 or 12.
GB0608611A 2005-05-04 2006-05-02 Electronic unit, electrically driven machine tool and a process for operating an electrically driven machine tool Expired - Fee Related GB2425978B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102005020830A DE102005020830A1 (en) 2005-05-04 2005-05-04 Method for operating a power tool, electronic unit and power tool

Publications (3)

Publication Number Publication Date
GB0608611D0 GB0608611D0 (en) 2006-06-14
GB2425978A true GB2425978A (en) 2006-11-15
GB2425978B GB2425978B (en) 2008-06-11

Family

ID=36603741

Family Applications (1)

Application Number Title Priority Date Filing Date
GB0608611A Expired - Fee Related GB2425978B (en) 2005-05-04 2006-05-02 Electronic unit, electrically driven machine tool and a process for operating an electrically driven machine tool

Country Status (2)

Country Link
DE (1) DE102005020830A1 (en)
GB (1) GB2425978B (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1216000A (en) * 1967-11-28 1970-12-16 Siemens Ag Automatically cutting or forming a workpiece
GB1485967A (en) * 1973-12-11 1977-09-14 Toyoda Machine Works Ltd Feed control device
SU952553A1 (en) * 1981-01-16 1982-08-23 Белорусский Ордена Трудового Красного Знамени Политехнический Институт Apparatus for limiting vibration in grinding machine
GB2199203A (en) * 1986-12-13 1988-06-29 Grundfos Int A static frequency converter
GB2201297A (en) * 1986-12-13 1988-08-24 Grundfos Int Association of electric motor and frequency converter
EP1663592A1 (en) * 2003-09-26 2006-06-07 Metso Paper, Inc. Chipper drive assembly

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1216000A (en) * 1967-11-28 1970-12-16 Siemens Ag Automatically cutting or forming a workpiece
GB1485967A (en) * 1973-12-11 1977-09-14 Toyoda Machine Works Ltd Feed control device
SU952553A1 (en) * 1981-01-16 1982-08-23 Белорусский Ордена Трудового Красного Знамени Политехнический Институт Apparatus for limiting vibration in grinding machine
GB2199203A (en) * 1986-12-13 1988-06-29 Grundfos Int A static frequency converter
GB2201297A (en) * 1986-12-13 1988-08-24 Grundfos Int Association of electric motor and frequency converter
EP1663592A1 (en) * 2003-09-26 2006-06-07 Metso Paper, Inc. Chipper drive assembly

Also Published As

Publication number Publication date
DE102005020830A1 (en) 2006-11-16
GB0608611D0 (en) 2006-06-14
GB2425978B (en) 2008-06-11

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20140502