Download Information Management of Equipment Productivity in Compliance with Digital Manufacturing Mode

Information Management of Equipment Productivity in Compliance
with Digital Manufacturing Mode
Li Wei, Chen Kun,
School of Mechanical and Electronic Engineering, Central South University, P.R. China, 410075
Abstract The importance of equipment manufacturing ability in the digital enterprise is analyzed, and
some problems on the management information of equipment manufacturing ability are pointed out.
Then taking machine tool for instance, the description model of the management information of
equipment manufacturing ability and the method of establishing corresponding database system are put
forward. The study provides a practical guide for the digital description of equipment manufacturing
ability in enterprises.
Key words Digital enterprise, Equipment manufacturing ability, Management information
，
1 Introduction
Nowadays, the digital manufacturing has become a developing orientation in the modern enterprise
because of the introduction of digital technology to the manufacturing technology. As a result, the
manufacturing activities increasingly depend on equipments. Therefore, the description of management
information of equipment manufacturing ability plays a key role in digital-based manufacturing.
In recent years, compared with the product information, the study on description of equipment
manufacturing ability information develops very slowly mostly because of the diversity and complexity
of equipment and the dynamic change of its environment, thus blocking the practical development of
equipment manufacturing ability information model to some extent.
By far, there are a few scholars both at home and abroad who have studied the information
description of equipment manufacturing ability. For example, Hu qingxi has investigated the facility
resource model based on hierarchical and feature technology in concurrent environment[1], and a
dynamic model of equipment resource for an integrated production environment was put out by Chen
weike and Wubo[2], et al. Although these scholars have made some progress in modeling management
information of equipment manufacturing ability, their studies don’t consider the details interrelated with
the machining activities of equipment, such as the information of cutting depth and productivity
computation, etc, which are important for the decision-making of many departments, such as process
planning department and product manufacturing department. So in this paper, taking machine tool for
instance, all information interrelated with the machining activities is abstracted from the complex
information of equipment. Finally the description of management information model of equipment
manufacturing ability and its database system are studied.
2 The basic demands for the management information of equipment
manufacturing ability
Different departments in an enterprise have different demands for the management information of
equipment manufacturing ability. For example, the product design department need consider the
producibility of product while designing, so some basic information of equipment manufacturing ability
should be understood, such as the material and structure of parts that the equipment can deal with, as
well as the accuracy that the equipment can arrive at. And the process planning department must know
all information about the equipment manufacturing ability in detail in order to determine the process
scheme of parts, such as information of cutting depth and man-hour, etc. However, in the traditional
management information system of equipment manufacturing ability, the management information
description model of equipment manufacturing ability is built only according to the different demands in
the different departments. And as a result, the information databases established by different
departments are various and independent from another. Such a kind of multilevel management may
certainly cause some troubles as follows:
1) The redundance of datum due to the lack of the unified and intact definition and expression of
275
equipment manufacturing ability information;
2) The impossibility in exchanging information among different departments because of the
difference of data expression;
3) The difficulty in maintaining and updating data owing to so many store locations of datum,
and waste of store space.
Under the digital manufacturing mode, the production task is usually finished by virtual enterprises,
and the environment of equipment changes with the different tasks. Then various equipments must be
rearranged quickly according to different task and their manufacturing abilities. Therefore it is essential
to found unified, shared and flexible information database of equipment manufacturing ability.
3 The foundation of the management information model of equipment
manufacturing ability
According to the analysis above, the management information model of equipment manufacturing
ability is built in feature-based modeling technology. The features of equipment manufacturing ability,
which are the technical property relevant to the manufacturing ability, embody the comprehensive
manufacturing ability of machine tool, cutting tool, clamp, measuring tool and machining environment,
etc. They may be divided into three classes as rendered below.
3.1 The feature of management
The feature of management is a combination of a group of information related to the management
of equipment manufacturing ability, whose main contents are as follows:
(1) The general information: It includes the name, type, number, specification, purchase date,
price, workshop, section, cell, fare per hour, useable hour and current status of equipment, etc.
(2
The information of the main components of equipment
1 The information of coordinate axis: It includes the amount of axes, the name and amount of
linkage axis, the name, removable distance and rotation accuracy of principal axis, etc.
2 The information of worktable: It includes the name, function, size, maximal load and maximal
removable distance of worktable.
3 The information of cutting tool storage: It includes the name, capacity, velocity, exchange mode
and exchange velocity of storage.
4 The information of cutting tool shelf: It includes the name, amount, removable distance and
turning angle of cutting tool shelf.
5 The information of numerical control system: It includes the type, supplier, CPU type,
memory type, memory capacity, numerical control mode, NC code and NC rule.
(3) The information of spare parts: It includes the name, type and amount of fittings, cutting tool,
clamp, measuring tool of machine tool, etc.
3.2 The feature of function
It embodies the manufacturing abilities that equipment possesses. Because most equipments not
only have the commonness of function feature of the same kind, but also their own personality, the
common and special features of equipment function are abstracted.
1 The common feature of function: Embodying the commonness of the same kind and reflecting
the common manufacturing ability of equipment, it is easily classified and has good commonality and
wide application. As a result, it can be described with fixed parameters and users may input some datum
according to the directions, whose main contents are considered as follows.
1 The machining range of parts
The machining information of material: It usually includes the ordinary machining material, the
special machining material and the material unable to be processed.
The machining information of parts: It mainly includes the machining range and method of
parts, the machining range of shape feature and the machining accuracy, which consists of the
independent accuracy and the accuracy of location. The independent accuracy comes from the accuracy
demands of single shape feature of part, such as the dimension accuracy for shaping, shape accuracy and
surface roughness, etc.
）
）
）
）
）
）
（）
）
①
②
276
③
The information of machining accuracy: It means the machining range of location accuracy.
2) The load of equipment: It includes machining task, beginning time, finishing time.
3) Machining data: It means cutting speed feed level and cutting depth. Machining experience
actual machining request and machining tool should be considered to determine the machining data
because of its complexity. The general steps are as follows:
determine cutting depth according to the reference information of machining data or
computation formula and actual machining request, and to primarily estimate cutting speed and feed
level;
calculate the rev of the principal axis on the basis of ;
finally determine the feed level and the rev of the principal axis according to the technical
parameter of machining tool;
calculate the cutting speed again;
checkout the machining data above according to such main machining parameters as cutting
force cutting power, etc. If the value of the main machining parameter is too big, the machining data
should be determined anew. There are such two kinds of method as calculation and table lookup for
checkout.
From what has been discussed above, the main information related to machining data can be gotten.
The information are related to relevant reference for selecting machining data, the calculation of cutting
speed and principal axis rev, the range and progression of the principal axis rev, feed level, the maximal
power transmitted by principal axis, the power of the main electromotor, the maximal cutting force that
equipment can bear, the calculation and table lookup of the cutting force and cutting power.
4) Productivity and machining cost: It includes the reference information to determine cutting
man-hour, the calculation information of the cutting man-hour and machining cost, etc.
(2) The special feature of function: Because it reflects the special manufacturing ability of the
equipment, it is difficult to be classified and has so narrow use that it only belongs to each enterprise. It
is described with some describing parameters defined by users according to their practice and users need
not only input the name of describing parameters, but also the specific values[3]. The manufacturing
ability of old lathe in one enterprise for boring an offset deep hole is just an example in point.
All kinds of feature information of the equipment manufacturing ability in each enterprise can be
described because the description parameter of the special function feature can be defined by users
themselves, which lay a good foundation for establishing a flexible, open feature information database
of the equipment manufacturing ability.
3.3 Accessorial feature
It is a group of information of the assisted function feature, such as cooling way the way of
excluding scrap iron, etc.
Some equipment doesn’t have all feature information introduced above. For example, in general
lathe there aren’t the storage information of cutting tool or the information of numerical control system.
Only the existing information is considered when modeling, can the store space be saved and can the
running speed be increased in establishing information database.
、
、
①
②
③
④
⑤
、
①
、
4 The establishment and management of the information database of equipment
manufacturing ability
Under the mode of digital manufacturing, in order to highly integrate and efficiently manage
information of equipment manufacturing ability, the technology of database and network can be
employed.
The information database of equipment manufacturing ability is established with SQL SERVER 2000,
name,
type, serial
number,
specification…,
fare per hour,
useable the
hour,
current status
which is a distributedGeneral
network
database
software.
Four
distributed databases,
including
authority
management database, the management feature database, function feature database and accessorial
feature database of equipment manufacturing ability, are designed. The forms in each database are
planned as table 1.
Machine tool
Management feature
：
Axis: name, turning accuracy of principal axis
277
Machining range of parts
Machined material: ordinary material, infrequent material, unable machined material
Machined parts: the shape, type, batch, maximal weight, maximal diameter
above the bed and knife shelf, maximal length of parts,
maximal diameter of bar stock
Machined shape feature: machining approach, shape feature, main parameter ZH,
range of ZH, size accuracy and surface roughness, shape accuracy name X,
machining range of X, location accuracy name W, machining range of W, the
measured surface of W, datum plane of W
Reference
information
Load of equipment: machining task, beginning time, finishing time
Hard alloy cutting tool of roughly turning cylindrical surface: the
material and diameter of workpiece, cutting depth, feed level,
remark
……
Calculation of cutting speed: formula, machining material, machining way,
knife material, cutting fluid, feed level, coefficient and index in formula,
remark of the rev of principal axis: formula
Calculation
Technical parameter: the range and progression of orthogyral rev of principal
axis, the range and progression of reversion rev of principal axis the range
and progression of feed level of Y-coordinate and X-coordinate, maximal
power transferred by principal axis, power of main motor, maximal cutting
force capable to be exerted
Machining data
，
Calculation of cutting force: formula, workpiece material,
material of cutting tool, processing way, coefficient and index in
formula, remark
……
Main cutting force of hard alloy cutting tool: workpiece material,
cutting depth, feed level, cutting speed, main cutting force,
remark
……
of
cutting man-hour
Reference for selecting cutting man-hour: the shape LJ, material and
rigidity of parts, the main parameter and range of LJ, shape feature XZH,
machining parameter of XZH, dimension of processing procedure, the
processing allowance, processing accuracy, surface roughness and
man-hour, remark
Calculation
Productivity and
Machining cost
Information
Information for
checkout
for checking
table
Common function feature
Function feature
Information of common lathe manufacturing ability
Knife shelf: name, amount, removable distance, turning angle
Spare parts: name, type, amount
Cutting man-hour of lathing cylindrical surface:
formula, accessorial length for testing cutting tool,
remark
……
Calculation of machining cost: formula, remark
Special function feature: user parameter name 1, user parameter name 2,
……
Accessorial feature: cooling mode, the mode of excluding the scrap iron……
Fig 1 information model of common lathe manufacturing ability
The hardware used for the network management of equipment manufacturing ability information
consists of the broad band local area network of enterprise the computers with good performance, etc.
The B/S structure is adopted among the servers of parent company and the servers of filiale or workshop,
which communicate with one another by TCP/IP protocol; The C/S structure is adopted among the
servers of filiale or workshop and the computers used for equipments, which communicate with one
、
278
another by COM+; The local area network of enterprise links the internet through the fire wall, which
makes it possible to access the long-distance data.
Name of database
Authority management
Management feature
Function feature
Accessorial feature
Table 1 information of the forms in each database
Name of data form
Login form authority management form
General information form
Information form of the main components of machine tool: information form of axis,
information form of worktable, information form of cutting tool storage, information
form of cutting tool shelf, information form of numerical control system
Information form of spare parts
range form of machined parts: information form of machined material,
information form of machined parts, information form of accuracy
Load form of equipment
Form of Machining data form: reference information form, calculation information
common form of the cutting speed, calculation information form of t principal axis
function rev, technical parameter information form of machine tool, calculation and
feature
consulting information form for checking
Productivity and machining cost forms: reference information form of
confirming machining man-hour, calculation information form of the
cutting man-hour, calculation information form of machining cost
Form of special function feature
Accessorial feature form
、
After logging in and authority permission, the forms in SQL SERVER database are visited through
the access to data module ADO of Microsoft which is programmed in the VBScript language of ASP
programming technology to consult network data dictionary. The forms in database are established
dynamically in the way of SQL SERVER programming technology DMO in order to be convenient for
users who don’t know how to use SQL SERVER to establish new forms of database. The maintenance
management of the forms of database is realized by some subprograms used for appending, deleting and
amending. The real-time task can be showed by contrasting the results of time function so that the
equipment can be managed in time.
5 Conclusion
Based on the mode of digital manufacturing, the feature-based model of equipment manufacturing
ability information is built, as well as an open feature database system of equipment manufacturing
ability. As a result, effective information management of equipment manufacturing ability may be
realized. With the help of feature database of equipment manufacturing ability, on one hand, the exact
real-time information data of equipment manufacturing ability can be provided to the different computer
application systems; On the other hand, new virtual enterprise can be formed quickly and rationally.
、
References
[1]Hu Qingxi. Facility resource model based on hierarchical and feature technology in concurrent
environment. Mechanical engineering in china,1999, 10(11):1231~1234(in Chinese)
[2]Chen Weike, Wu Bo, et al. Research and application of dynamic equipment resource modeling in
heavy machinery CAPP. Mechanical engineering in china, 1996, 7(4):62~ 64 (in Chinese)
[3]Li Wei. Information description method based on part-machine tool feature matching.
Computer integrated manufacturing system—CIMS, 2002, 8(12):1002~1005 (in Chinese)
279