The present invention relates to devices for generating NC programs for hole machining, and particularly to a device for automatically generating numerical control (NC) programs for hole machining based on CAD data.
An NC hole-machining programming device disclosed in Japanese Laid-Open Patent Publication 170692/1994 detects a chamfering shape included in the hole-machining forms from CAD data, and determines a hole machining method based on the detected chamfering shape. The above publication describes that a hole machining method is selected according to data indicating internal diameter and depth of a hole, and the chamfered shape formed on the opening edge of the hole, included in the CAD data of hole-machining forms. For instance, drilling is selected as a machining method for a hole with no chamfer, and drilling and reaming is selected for a hole with a chamfer. Then, a tool type, a drill or a reamer, is determined in accordance with the selected hole machining method.
Since conventional NC hole-machining programming device selects a hole machining method based on a chamfer and a chamfering angle, they are not capable of handling various types of hole machining such as tapping or complicated hole-machining forms.
The present invention has been made to solve above problems. A first object of this invention is to provide an NC hole-machining programming device that can deal with various hole machining such as tapping and stepped-hole machining, as well as drilling or reaming.
A second object of the invention is to provide an NC hole-machining programming device that can deal with complicated hole-machining forms.
An NC hole-machining programming device according to this present invention includes: a tool information storing unit for storing tool information including types and sizes of tools used for hole machining; a form recognizing unit for extracting a cylindrical surface and conical surface as a local geometry which constitutes a hole-machining form of target objects based on CAD data; a machining method determining unit which generates a hole-machining-form pattern based on the hole-machining form detected by the form recognizing unit and determine machining methods based on the hole-machining-form patterns; a tool determining unit for selecting a tool in accordance with the machining methods determined by the machining method determining unit with reference to the tool information; a tool path determining unit which determines a tool path for each tool selected by the tool determining unit; and an NC program generating unit which generates a NC programs based on the tool paths determined by the tool path determining unit.
FIG. 1 is a block diagram illustrating an embodiment of an NC hole-machining programming device according to the present invention.
FIG. 2 is a flowchart illustrating steps for determining machining methods.
FIGS. 3 and 4 is diagrams illustrating examples of hole-machining forms.
FIG. 5 is a diagram illustrating an identifier table.
FIG. 6 is a diagram illustrating hole-machining-form patterns.
FIG. 7 is a diagram illustrating a machining method table.
FIG. 8 is a diagram illustrating relations between hole-machining-form patterns and the machining methods.
FIG. 9 is a diagram illustrating relations between the hole-machining-form patterns and the machining methods.
FIG. 1 is a block diagram illustrating a configuration of an NC hole-machining programming device according to the present invention. The NC hole-machining programming device 1 illustrated in FIG. 1 includes a form recognizing unit 2 , a machining method determining unit 3 , a pattern information storing unit 41 , a tool information storing unit 42 , a tool and tool-path determining unit 5 , and an NC program generating unit 6 . The NC hole-machining programming device 1 illustrated in FIG. 1 is composed of a microcomputer, and the pattern information storing unit 41 and the tool information storing unit 42 are both composed of memory of the microcomputer.
The form recognizing unit 2 detects a machining form of a target object from three-dimensional CAD data 100 , and identifies a hole-machining form based on the detected form. FIG. 3 is a diagram illustrating an example of the machining form of the target object detected by the form recognizing unit 2 . The machining form illustrated in FIG. 3 includes two hole-machining forms indicated by “a” and “b”. Each of the hole-machining form illustrated in FIG. 3 is composed of cylindrical surface and conical surfaces. The form recognizing unit 2 identifies each of the hole-machining form by extracting a cylindrical surface and a conical surface arranged coaxially. Hereinafter, the cylindrical surface or the conical surface, which constitutes the hole-machining form is referred to as a local geometry.
The CAD data 100 includes dimensions of the local geometry, or more specifically, internal diameter and depth of a cylindrical surface, and depth and apex angle of a conical surface, each of which constitutes hole-machining forms. The CAD data 100 also includes machining information of the local geometries such as a screw thread and a reamer.
The machining method determining unit 3 determines machining methods used for the hole-machining form detected by the form recognizing unit 2 by carrying out the following processing.
The machining method determining unit 3 firstly identifies features of the local geometry constituting the hole-machining form, extracted by the form recognizing unit 2 . The local geometry having surface of a cone with apex angle 90° is recognized as a chamfer. FIG. 4 is a diagram illustrating examples of hole-machining forms composed of a plurality of local geometries. The local geometry of the hole-machining form illustrated in FIG. 4 ( a ) is detected from the top of the hole, and this hole-machining form is recognized as “cone (chamfer)—cylinder—cone”. In the same manner, the hole-machining form illustrated in FIG. 4 ( b ) is recognized as “cone (chamfer)—cylinder (screw thread)—cone”, and the hole-machining form illustrated in FIG. 4 ( c ) is recognized as “cone (chamfer)—cylinder—cylinder—cone”.
The machining method determining unit 3 generates hole-machining-form patterns which indicates the recognized local geometries using identifiers. FIG. 5 is a diagram illustrating an identifier table storing the local geometries and corresponding identifiers. The identifier table illustrated in FIG. 5 is stored in the pattern information storing unit 41 .
FIG. 6 is a diagram illustrating examples of hole-machining-form patterns. The hole-machining-form pattern illustrated in FIG. 6 ( a ) is represented as “oct”; the hole-machining-form pattern illustrated in FIG. 6 ( b ) is represented as “oCt”; and the hole-machining-form pattern illustrated in FIG. 6 ( c ) is represented as “occt”. The hole-machining-form pattern is generated by combining each of the identifiers indicating the local geometries in the order of the detection (from top side to bottom side of the hole-machining form).
The machining method determining unit 3 determines the machining method based on the hole-machining-form pattern. FIG. 7 is a diagram illustrating a machining method table storing the hole-machining-form patterns and corresponding machining methods. The machining method table illustrated in FIG. 7 is stored in the pattern information storing unit 41 together with the identifier table illustrated in FIG. 5. The machining method determining unit 3 refers to the machining method table (FIG. 7) to select the machining method corresponding to the hole-machining-form pattern.
FIG. 8 is a diagram illustrating relations between the hole-machining forms and the machining methods. Drilling is selected for the hole-machining form illustrated in FIG. 8 ( a ); tapping is selected for the hole-machining form illustrated in FIG. 8 ( b ); and stepped-hole machining is selected for the hole-machining form illustrated in FIG. 8 ( c ).
The tool and tool-path determining unit 5 selects tools required for machining based on the machining method determined by the machining method determining unit 3 , and dimension of the hole-machining form (internal diameter and the depth of a cylinder, or depth and apex angle of a come) included in the CAD data, and determines paths for the selected tools.
The tools used for each machining method are predetermined. For example, a drilling tool is used for drilling, a drilling tool and a tapping tool are used for tapping; a drill and a reamer are used for reaming; and a drill, an end mill and the like are used for stepped-hole machining. In addition to these tools, a spotting tool used for positioning is added if required. Furthermore, when data indicating a cone with apex angle 90° is included in the three-dimensional CAD data 100 , or when an identifier “o” indicating chamfering is included in the hole-machining-form pattern, a chamfering tool is added.
For instance, for the hole-machining form illustrated in FIG. 8 ( a ), a drilling tool and a chamfering tool are selected for drilling and chamfering. For the hole-machining form illustrated in FIG. 8 ( b ), a drilling tool, a tapping tool and a chamfering tool are selected for tapping and chamfering. For the hole-machining form illustrated in FIG. 8 ( c ), a drilling tool, an end milling tool and a chamfering tool are selected for stepped-hole machining and chamfering.
Determination of the machining method by the machining method determining unit 3 and selection of tools and determination of the tool path for the tool selected by the tool and tool-path determining unit 5 are performed for every hole-machining form extracted by the form recognizing unit 2 . The tool path for a plurality of holes having the same finishing form is determined so that continuous machining is performed using a common tool.
The NC program generating unit 6 creates a series of NC programs based on the tool information and the tool path obtained by the tool and tool-path determining unit 5 , and outputs the programs to a control unit of an NC machine tool 200 . At the same time, Various control data such as designation of a tool rotational frequency and commands for fast feeding of the tool is added to the NC programs.
FIG. 2 is a flowchart illustrating a series of processing steps in the machining method determining unit 3 . As described above, the machining method determining unit 3 refers to the machining method table (FIG. 7) stored in the pattern information storing unit 41 , and determines the machining method for the hole-machining form 300 identified by the form recognizing unit 2 (step ST 1 ). Then, whether the machining method has been determined is judged (step ST 2 ). If the machining method has been determined, then the process is terminated (step ST 7 ). Meanwhile, if the hole-machining form is too complicated to determine the machining method, the procedures of step ST 3 through step ST 6 are performed. More specifically, the local geometries are detected from the bottom side of the hole (step ST 3 ), and the machining method corresponding to the detected local geometry is determined (step ST 4 ). Then, whether the machining method has been determined is judged (step ST 5 ). If the machining method cannot be determined, the process of step ST 3 is repeated. If the machining method has been determined, whether the machining method for the entire hole-machining form has been determined is judged (step ST 6 ).
FIG. 9 is a diagram for explaining processing steps for determining the machining method for a complicated hole-machining f orm.
The identifier “t” is given to the local geometry of the bottom-side cone illustrated in FIG. 9 ( a ) (step ST 3 ). However, since the hole-machining-form pattern “t” is not included in the machining method table (FIG. 7), the machining method cannot be determined in step ST 4 . Accordingly, the judgment in step ST 5 is “No”, and the process of step ST 3 is repeated. In step ST 3 , as illustrated in FIG. 9 ( b ), the cylindrical surface “c” is detected as a next local geometry, and the hole-machining-form pattern “ct” is obtained. For the hole-machining-form pattern “ct”, drilling is selected based on the machining method table (step ST 4 ). Accordingly, the judgment in step ST 5 is “Yes”, and the process of step ST 6 is performed. In step ST 6 , whether the machining methods for the entire hole-machining form have been determined is judged. In this case, the judgment result is “No”, so the process of step ST 3 is repeated, and the rest of the local geometries are detected in the same manner. More specifically, as illustrated in FIG. 9 ( c ), a cone “t” is detected as a next local geometry, and the hole-machining-form pattern “t” is obtained (step ST 3 ). However, since the hole-machining-form pattern “t” is not included in the machining method table, the machining method cannot be determined in step ST 4 . Accordingly, the judgment in step ST 5 is “No”, and step ST 3 is repeated. In step ST 3 , as illustrated in FIG. 9 ( d ), the cylindrical surface “c” is detected as a next local geometry, and the hole-machining-form pattern “ct” is obtained. For the hole-machining-form pattern “ct”, drilling is selected based on the machining method table (step ST 4 ). Accordingly, the judgments in step ST 5 and step ST 6 are “Yes”, and the processing is terminated. Consequently, the hole-machining form in FIG. 9 is divided into two hole-machining form with different diameters and lengths, each of which is composed of a cylinder and a cone, and drilling using different drilling tools is selected for each of the portions.
As illustrated in FIG. 9, a plurality of hole-machining-form patterns constituting a single hole-machining form is generated, and a machining method is determined for each of the generated hole-machining-form patterns, whereby machining methods can be determined for complicated hole-machining forms.
In addition, the machining methods can be determined by detecting the hole-machining-form pattern of the local geometry from the top-face side of the hole.
In the above description, the local geometries having surface of a cone with apex angle 90° is considered as a chamfer. However, the surface of a cone with apex angle other than 90° may also be considered as a chamfer. Characters other than alphabet may be used as the identifiers indicating the local geometry, and the hole-machining-form patterns may be represented without using identifiers.
As described above, the NC hole-machining programming device according to this present invention includes:
a tool information storing unit which stores tool information including types and sizes of all tools attachable for hole machining;
a form recognizing unit which detects a hole-machining form based on the CAD data and extract a cylindrical surface or a conical surface included in the hole-machining form;
a machining method determining unit which generates a hole-machining-form pattern based on the hole-machining form detected by the form recognizing unit and determine machining methods based on the hole-machining-form patterns;
a tool determining unit which selects a tool in accordance with the machining methods determined by the machining method determining unit with reference to the tool information;
a tool path determining unit which determines a tool path for each tool selected by the tool determining unit; and
an NC program generating unit which generates a series of NC programs, based on the tool paths determined by the tool path determining unit. Therefore, various hole machining such as tapping and stepped-hole machining, as well as drilling or reaming can be handled with the NC hole-machining programming device according to this invention.
Furthermore, the machining method determining unit repeats a following process for a hole-machining form having with a complicated shape: obtaining the hole-machining-form pattern for a portion of the hole-machining form and determining a machining method for that portion, and then determining a machining method for the hole-machining form as a combination of a plurality of machining methods. By repeating this process, a complicated hole-machining form can be handled.