Method for detecting abnormality of temperature sensor in machine tool

• US 7,766,541 B2
• Filed: 12/05/2007
• Issued: 08/03/2010
• Est. Priority Date: 12/18/2006
• Status: Expired due to Fees

• Current Assignee: Okuma Corporation
• Original Assignee: Okuma Corporation
• Inventors: Sato, Reiji
• Primary Examiner(s): Verbitsky; Gail
• Assistant Examiner(s): Jagan; Mirellys
• Application Number:
  US11/950,561
• Publication Number:
  US 20080144693A1
• Time in Patent Office: 972 Days
• Field of Search: 374/1, 374/110, 374/166, 374/141, 374/112
• US Class Current: 374/1
• CPC Class Codes: G01K 15/00 Testing or calibrating of thermometers
• CPC Class Codes: G01K 15/007 Testing

Abstract

The invention relates to a method for detecting an abnormality of a temperature sensor. A plurality of temperature sensors are preliminarily grouped for each of predetermined attachment areas of a machine tool, and after a temperature of each part is measured in S1, the detected temperatures are classified in S2 for each of the grouped attachment areas, and then sorted in descending order in S3. Subsequently, a difference ΔT between any closest two of the detected temperatures is obtained in S4, and then compared with a preset limit value γ in S5, when ΔT exceeds the limit value γ, temperature sensors in a corresponding attachment area are determined abnormal in S6, and an alarm is displayed.

Claims

1. A method for detecting abnormalities of a temperature sensor in a machine tool in which a plurality of temperature sensors are arranged at different parts of the machine tool, the method comprising the steps of:

preliminarily grouping the temperature sensors into one or a plurality of predetermined attachment areas of the machine tool at which temperatures vary in a similar manner;

setting a limit value of variations of detected temperatures of each group of the plurality of temperature sensors belonging to the same group in the predetermined attachment areas;

detecting temperatures of each part of the machine tool by the plurality of sensors;

grouping the detected plurality of temperatures in accordance with the corresponding group of temperature sensors;

obtaining variations of the detected temperatures in the same temperature group, respectively;

comparing each of the variations with a corresponding preset limit value of each group, respectively; and

determining the temperature sensors associated with the variation to be abnormal when one of the variations exceeds the limit value.

2. A method for detecting abnormalities of a temperature sensor in a machine tool in which a plurality of temperature sensors are arranged at different positions, the method comprising the steps of:

preliminarily grouping the temperature sensors into one or a plurality of predetermined attachment areas of the machine tool;

respectively obtaining variations of detected temperatures by the plurality of temperature sensors belonging to the attachment areas;

comparing each of the variations with a corresponding preset limit value; and

determining the temperature sensors associated with the variation to be abnormal when one of the variations exceeds the limit value,

said method further comprising a step of;

prohibiting a correction of machining dimensional errors from being changed in thermal displacement correction of the machine tool, when the temperature sensors are determined abnormal.

3. A method for detecting abnormalities of a temperature sensor in a machine tool in which a plurality of temperature sensors are arranged at different positions, the method comprising the steps of:

preliminarily grouping the temperature sensors into one or a plurality of predetermined attachment areas of the machine tool;

respectively obtaining variations of detected temperatures by the plurality of temperature sensors belonging to the attachment areas;

comparing each of the variations with a corresponding preset limit value; and

determining the temperature sensors associated with the variation to be abnormal when one of the variations exceeds the limit value,

wherein the attachment areas are divided into four areas;

an area that is affected by heat sources and classified for each of the heat sources;

an area that is not affected by the heat sources, is in or faces a machining space;

an area that is not affected by heat sources, is not in or does not face a machining space and is proximate to a floor surface; and

an area that is not affected by the heat sources, is not in or does not face the machining space, and is spaced away from the floor surface,

wherein when a plurality of temperature sensors are in each of the classified areas, abnormalities of the temperature sensors in the each of the areas are detected.

4. The method for detecting abnormalities of temperature sensors in the machine tool according to claim 3, comprising a step of:

prohibiting a correction of machining dimensional errors from being changed in thermal displacement correction of the machine tool, when the temperature sensors are determined abnormal.

5. A method for detecting abnormalities of a temperature sensor in a machine tool in which a plurality of temperature sensors are arranged at different positions, the method comprising the steps of:

preliminarily grouping the temperature sensors into one or a plurality of predetermined attachment areas of the machine tool;

respectively obtaining variations of detected temperatures by the plurality of temperature sensors belonging to the attachment areas;

comparing each of the variations with a corresponding preset limit value; and

determining the temperature sensors associated with the variation to be abnormal when one of the variations exceeds the limit value,

wherein the each of the variation of detected temperatures is set equal to a difference between detected temperatures closest to each other when a plurality of temperature sensors in the same attachment area are sorted in descending or ascending order.

6. The method for detecting abnormalities of temperature sensors in the machine tool according to claim 5, comprising a step of:

prohibiting a correction of machining dimensional errors from being changed in thermal displacement correction of the machine tool, when the temperature sensors are determined abnormal.

7. The method for detecting abnormalities of temperature sensors in the machine tool according to claim 5, wherein the attachment areas are divided into four areas:

an area that is affected by heat sources and classified for each of the heat sources;

an area that is not affected by the heat sources, is in or faces a machining space;

an area that is not affected by the heat sources, is not in or does not face a machining space and is proximate to a floor surface; and

an area that is not affected by the heat sources, is not in or does not face the machining space, and is spaced away from the floor surface,

wherein when a plurality of temperature sensors are in each of the classified areas, abnormalities of the temperature sensors in the each of the areas are detected.

8. The method for detecting abnormalities of temperature sensors in the machine tool according to claim 7, comprising a step of:

prohibiting a correction of machining dimensional errors from being changed in thermal displacement correction of the machine tool, when the temperature sensors are determined abnormal.