Gear cutting – milling – or planing – Milling – Process
Reexamination Certificate
1999-07-27
2004-07-13
Wellington, A. L. (Department: 3722)
Gear cutting, milling, or planing
Milling
Process
C409S134000, C409S137000, C409S167000, C409S235000, C483S014000, C029SDIG009
Reexamination Certificate
active
06761515
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of high speed machining, machine-tools mobile on three axes X, Y and Z, and more particularly to modifications allowing to improve the machining travel of this type of machine.
2. Discussion of the Background
Classically, the tools used in very high speed machining are of the rotary type and are placed at the end of a unique tool-carrying ram mounted moveable along three axes so as to allow machining on a big length, a big width and a big depth, as well as tool exchange, gripping and collection functions in magazines conceived for that purpose.
Generally, these machines comprise several main parts, i.e.:
an actual machining station comprising the tool driven in rotation at the end of the ram and shaping the part to be machined,
a driving station placed near the machining station and constituted by a combination of driving mechanisms ensuring the movements along the axes X, Y, Z of the tool-carrying ram, which also ensures, via an electric spindle, the rotary movement of the tool carried at the end,
a control station collaborating with the driving station according to a pre-established instructions program to ensure and to manage the different machining operations and stages of the different parts to be machined.
The machining station can classically comprise several subsets offering as many additional functions. Thus, for example, a magazine or a tool storage device offers several machining tools to the ram mobile on three axes coming to leave and take the tools, allowing it to ensure as many machining functions as possible on a part to be machined. The machining station can also comprise a device for exchanging parts to be machined managed by the control module and ensuring the exchange between the parts having just been machined and the ones still to be machined.
With the benefit of its experience in the field of high speed machining along three axes and on machines called mono-spindle, the applicant has conceived high precision machines operating at a high velocity capable of achieving high accelerations and rapidity of function in their movement along three axes X, Y and Z by the use of a logical cinematic structure and innovative driving means, well above that achievable by classical machining machines. The applicant has noticed that these machines, even though they have matched the users requirements up until now, can in some situations prove to have limited use in their machining travel. In fact, to reply to the new criteria of acceleration and rapidity of function required for very high speed machining machine-tools, combined with the concern for compactness of the machines, the travels along the three different axes are comprised in intervals defined by the mechanical or geometrical limits of the machine, which intervals can prove to be too short for some applications.
The limitation to the travel is a difficulty often found in the conception of machine-tools and several devices can be found in the prior art, ensuring a movement of the part to be machined so as to enable it to get nearer the tool thus avoiding unnecessary travel and travel times (until the tool is in contact with the part to be machined and begins the machining stage) which would reduce the machine's performance. Nevertheless, no device has been conceived to enable the lengthening of the machining travel of a machining machine-tool of the type comprising a tool-carrying ram which, ensuring functions of tool gripping, exchange, guidance, and driving moves along three axes X, Y and Z, the three axes forming an orthogonal spatial system of axes and Z being the longitudinal axis of the machine and of which the movements are ensured by linear motors, such as in the case of the machines conceived by the applicant. In fact, the total freedom of movement of the tool-carrying ram combined with its speed due to the use of linear motors, brings new technical criteria and opens a field of possibilities in programming machining on one part to be machined, never previously reached. The existing machine-tools using a tool-carrying ram moving along three axes are, on the whole, less fast and and less precise, and do not have the dynamic constraints of the ones conceived by the applicant, in view of their size, higher travels obtained, or less performing driving means. In addition, the existing devices which ensure the movement of a part to be machined are essential to the following machining stage because the tools of the classical machine-tools do not move parallel to the movements of the part to be machined. Thus, on the axes followed for the movements of the part to be machined, the ram, the headstock and/or the tool-carrying spindle stay fixed.
The applicant has thus studied the concept of an innovative method enabling the widening of the capacities of machines' machining travel. The difficulty of such a concept is to offer a device enabling to adapt to a machine already answering perfectly to users' requirements in most applications and for most of the parts to be machined so that it is not built-into the machine to avoid an overload when the device is not necessary. Furthermore, as the increase of the lengths of machining travels of a machine-tool have for direct and known consequence to reduce the velocity of the machine, such a device would be set in motion or would start to function only when the part or the side of the part to be machined (via a machining program) so requires.
SUMMARY OF THE INVENTION
In view of this situation and the specifications required, the applicant has carried out research aimed at achieving the aforementioned targets. This research has led to the conception of a method which does not reduce the performance of the basic machining machine-tool, integrable but not built-in to it, and enabling once it has started to function, the machining of parts to be machined which are longer, wider or higher.
According to the main characteristic of the invention, the method for lenghtening the machining travel of a high speed machine-tool of the type comprising a tool-carrying ram ensuring tool gripping, exchange, guidance and driving and moving along three axes X, Y and Z, the three axes forming an orthogonal spatial system of axes and Z being the longitudinal axis of the machine, the movements being ensured by linear motors, is remarkable in that it consists in combining to the machining movements of the tool-carrying ram along one or several axes, one or several rectilinear movements of the part to be machined by parametering and digitizing the relative travels and speeds of the part to be machined with respect to the tool-carrying ram.
This method is particularly advantageous as it enables to lengthen the useful travel of the tool-carrying ram of the machine-tool without reducing the dynamic performances. In fact, the mobility on one or several axes of the part to be machined with respect to the tool-carrying ram already mobile on these three axes enables not only to bring the part to be machined closer to avoid the non machining times and reduce the unecessary travel of the tool-carrying ram, which is what classically occurred in the devices of the prior art but also to reduce these times of bringing closer by moving the tool-carrying ram and the part to be machined along parallel axes but in an opposite way thus reducing dead time.
In this precise application, once the part to be machined and the tool-carrying ram are close, several machining configurations are possible:
either the tool-carrying ram is alone in executing the travel and rotatably driving the tool towards the fixed part to be machined,
or the part to be machined is alone in executing the travel in moving towards the tool-carrying ram fixed with the tool rotatably driven,
or the part to be machined and the tool-carrying ram both move along a parallel direction but in an opposite way.
According to a particularly advantageous characteristic of the invention, this method consists in parametering and digitizing the relat
Azema Andre
Laur Raymond
Cadugan Erica E
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Renault Automation Comau
Wellington A. L.
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