Metal working – Method of mechanical manufacture – Impeller making
Reexamination Certificate
1999-08-13
2001-02-13
Wellington, A. L. (Department: 3722)
Metal working
Method of mechanical manufacture
Impeller making
C029SDIG001, C082S001110, C409S132000
Reexamination Certificate
active
06185818
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for taking a plurality of products having free-curved surfaces from a long bar member and a method thereof, and more particularly to an apparatus suitable for machining products having thin free-curved surfaces such as a steam turbine blade, and a method thereof.
DESCRIPTION OF THE RELATED ART
Conventionally, products having free-curved surfaces have been manufactured by a plurality of machine tools, some of which have simultaneously-controlled axes. As an example of the product having a free-curved surface, a blade has been used for a steam turbine. An example in which the steam turbine blade is machined will be described below. One bar member is machined by a plurality of machine tools to obtain one product (turbine blade). At machining steps, a root section is formed on one end of the bar member by a first machine tool, and a profile section (steam passage section) is then formed by another machine tool. The bar member is manually removed or attached on each machine tool (Prior art 1).
At a step of machining the turbine blade, a twisted blade should be formed on a surface, that is, a free-curved surface should be formed. Therefore, a machine tool having a plurality of simultaneously-controlled axes (four axes or more) is required. This machine tool has been disclosed in Japanese Patent Examined Publication No. HEI 5-26615, for example. Such a turbine blade has a dimension and size varied according to efficiency of the steam turbine, steam conditions and the like. For this reason, a small quantity of various products have been manufactured.
In recent years, electronic technology has been advanced rapidly. As a technique for implementing FA (Factory Automation) of a machine shop, an automatic production system such as FMS (Flexible Manufacturing System) has been developed. Such an automatic production system automatically performs delivery of a raw member, rough machining, handling, transfer, finishing and the like (Prior art 2).
According to the Prior art 1, however, it is necessary to perform two steps of machining a root section and a profile section by separate machine tools. Furthermore, works of forming the root section on the bar member and then removing and attaching the bar member to another machine tool are manually performed. Therefore, a lot of time and labor are required. In the case where the machining time taken for each step, for example, of machining the steam turbine blade or the like is short, the attaching and removing works should be performed frequently and at short interval. Accordingly, the machine operators to handle the machine tools should be stuck to the machine tools whole time other than the real handling time of the attaching and removing works. Consequently, the works have very poor productive efficiency.
According to the Prior art 2, the machining step is divided into a plurality of steps. At each step, attachment, removal and delivery are automatically performed. For this reason, when automatically attaching and removing bar member and half-machined product, whole equipment should be stopped if gripping is failed. Thus, there is a possibility that productivity might be deteriorated. In addition, in the case where a small amount of various products are manufactured, machining time for each step cannot be equalized depending on the kinds of the products to be machined. For this reason, while a machine tool used at a step taking long machining time is operating, a machine tool used at a step taking short machining time does not operate in some cases. Consequently, there is a higher possibility that an operation rate of the whole equipment might be lowered. Furthermore, a computer for controlling machine tools, a delivery system and the like is required and a program for automatically performing manufacturing steps becomes complicated so that an equipment cost is greatly increased.
Machining of other products having no free-curved surface also have these problems.
SUMMARY OF THE INVENTION
In order to solve the above-mentioned problems, it is an object of the present invention to provide a long bar member machining apparatus comprising a main chuck head having one control axis for holding and rotating a long bar member, a head stock assembly having three or more control axes, and a bar member feeder for feeding the long bar member to the machining position by a predetermined distance, wherein at least four axes are simultaneously controlled to obtain a plurality of products having free-curved surfaces from the long bar member.
If the long bar member fed by the bar member feeder is machined by a cutting tool provided on the head stock assembly having a plurality of simultaneous-control axes by means of the single machining apparatus, all steps are subjected to machining operation so that a plurality of products having free-curved surfaces can continuously be obtained.
The present invention provides a long bar member machining apparatus comprising a main chuck head having a control axis for holding the long bar member in a predetermined position and for rotating the long bar member around the axis, a machine bed for supporting the main chuck head, a head stock assembly having at least three control axes, that is, an axis for moving a cutting tool for machining the long bar member held by the main chuck head in parallel with the longitudinal axis of the long bar member, an axis for moving the cutting tool transversely in horizontal direction, and an axis for moving the cutting tool transversely in substantially vertical direction, the head stock assembly being provided on the machine bed, a bar member feeder for feeding, to a feeding side of the main chuck head, the long bar member from which a plurality of products are taken, and a controller for simultaneously controlling the four axes to continuously obtain the products having free-curved surfaces from the long bar member fed to the main chuck head by the bar member feeder. Above-mentioned product includes a finished or a half-finished product, and is machined by the long bar member machining apparatus according to the present invention.
Thus, the rotation of the long bar member held by the main chuck head, and the cutting tool provided on the head stock assembly which can be moved in directions of at least three axes, that is, the axis for movement parallel with the longitudinal axis of the long bar member, the axis for transverse movement in horizontal direction, and the axis for transverse movement in vertical direction are simultaneously controlled by the controller. Consequently, the product having a free-curved surface can be machined by the machining apparatus. Furthermore, if the long bar member obtained after cutting out the product is fed by the bar member feeder, a plurality of products can be taken therefrom.
If the control axis for causing the cutting tool provided on the head stock assembly to swivel around the vertical axis perpendicular to the longitudinal axis of the long bar member in a direction of the longitudinal axis of the long bar member is provided, and the five axes including the control axis are simultaneously controlled by the controller to continuously machine products having free-curved surfaces, a degree of freedom of machining is increased so that various cutting tools can be used to form free-curved surfaces easily.
If the long bar member machining apparatus further comprises an sub-chuck head for holding an end of the long bar member fed by the bar member feeder, a holding chuck provided on the sub-chuck head for holding the long bar member on a periphery, and a pressing chuck provided on the sub-chuck head for holding the long bar member by pressing an end face of the bar member, the internal stress and strain in the bar member caused during machining process can easily be released and the circumferential eccentricity on the end support section can easily be eliminated by recutting the end support section.
The present invention provides a long bar member machining method comprising the steps of
Awai Masahiro
Ito Masaru
Yamasaki Toshiro
Yamazaki Goro
Ergenbright Erica
Kawasaki Jukogyo Kabushiki Kaisha
Marshall O'Toole Gerstein Murray & Borun
Wellington A. L.
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