Metal working – Method of mechanical manufacture – With testing or indicating
Reexamination Certificate
2003-04-16
2004-03-09
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
With testing or indicating
C029S447000, C029S800000, C408S23900A, C409S232000
Reexamination Certificate
active
06701597
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of force-transmitting clamping of a tool, in particular with a shaft in an opening of a tool receptacle by shrinking including heating and cooling, wherein the axial insertion depth of the shaft in the opening is provided by an adjustment.
In this method the heating is preferably performed inductively. In the method with thermal clamping of tools, a high-precise mounting of the tools, for example drills, mills and the like is obtained. The tool receptacle is heated at least in the region of a sleeve part which contains the opening so that the opening is increased. The tool is inserted with its shaft in the thusly increased opening. During subsequent cooling the shaft of the tool is forced-transmittingly held in the opening of the tool receptacle which is shrunk by cooling. The diameter of the opening of the tool receptacle and the shaft of the tool are selected so that during cooling a force-transmitting (force-locking) and non rotatable connection is produced, such that during fast rotation it is not released under the action of centrifugal forces. In order to remove the tool, the tool receptacle is again heated, and the opening is enlarged until the tool with its shaft can be withdrawn from the tool receptacle. The withdrawal is possible since the heating propagates from outside inwardly, so that first for example the sleeve part of the tool receptacle is heated up, before the heat reaches the shaft of the tool which is clamped in the receptacle. Thereby the sleeve portion is first expanded, so that the still cold shaft of the tool can be released during unchanging from the opening.
During the clamping of the shaft of the tool, the axial insertion depth of the shaft can be exactly adjusted in the opening of the tool receptacle, also with consideration of certain circumstances that during the subsequent cooling a length change will occur. It is known for clamping a tool, first to heat the tool receptacle until its opening is increased so that subsequently the tool with its shaft can be inserted into the opening. The insertion depth in the insertion is selected in correspondence with an assumption that an abutment which is integrated in the tool receptacle can be additionally provided. The insertion and the adjustment of the insertion depth are performed in heated condition of the tool receptacle with inwardly propagating terminal expansion of the inner receiving opening. This method operates only when during the short heating phase a sufficient time is available and when the tool is used with low thermal expansion, such as for example of hard metal or ceramic, since with these tool materials one must not be afraid that the heat supplied to the tool receptacle can be transferred to the tool shaft and cause its expansion and clamping during the insertion.
It is further known to adjust first an adjustment screw which is coaxially held in the tool receptacle, by means of an adaptor inserted in the opening of the tool receptacle in its cold condition, with respect to the axial nominal position. The adjustment can be performed by contacting or optical measurement, for example of the tip of the tool. After the complete adjustment of the coaxial adjustment screw and removal of the adaptor, the shrinking of the tool is performed by its shaft. During heating of the enlarged opening of the tool receptacle the tool can be inserted with its shaft so far until the end side of the shaft which is opposite to the tool tip axially abuts against the adjustment screw. The adjustment in this manner is not very accurate. Inaccuracies occur within the range of +/−0.05 mm. This inaccuracy results from the fact that the tool, with respect to the above mentioned end side which reaches the contact with the adjusting screw, is not accurately treated. Also, the arrangement of the adjusting screw which is screwed in the central threaded opening coaxially to the opening is an additional expense, and also the thread pitch can cause additional adjustment errors.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method of the above mentioned general type, which avoids the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide a method of the above mentioned general type, which provides a very precise adjustment of the insertion depth of the tool with a simplified structural expenses of the tool receptacle.
It is also an object of present invention to provide a method of the above mentioned general type, which does not have any limitations with respect to the material pair tool receptacles/tool.
It is a further object of the present invention to provide a method of the above mentioned general type, in which not only tools with low thermal expansion can be utilized, such as hard metal, ceramic and the like, but also tools composed of other materials can be used as well.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated in a method of the above mentioned general type, in which with the tool coaxially supported relative the tool receptacle, for positioning of the tool a movable contact piece is arranged at its free end for abutment, and the tool is clamped between the contact piece at one side and a counterforce on the other side which acts on the tool in an opposite direction and opposite to an insertion into an opening of a tool receptacle before the heating starts, and during the heating it remains clamped, so that after reaching a predetermined nominal value during insertion of the shaft into the opening of the receptacle it is stopped.
In the inventive method the adjusting of the insertion depth of the tool shaft in the tool receptacle is performed before the heating of the tool receptacle. After the dimension reference, the relevant cutting geometry and not the end-side rear side of the tool shaft is utilized, and therefore a high quality exact adjustment is possible. With respect to the apparatus expenses, in particular the design of the tool receptacle, a simplifcation is provided because an inner adjusting screw with a threaded opening for receiving the same can be dispensed with and therefore the tool receptacle is simpler and less costly, and the danger of a pretensioning of mechanical parts is also eliminated. Before the heating of the tool receptacle, the movable contact piece is placed on the free end of the tool in abutment, so that the tool activates an oppositely directed, also coaxial, loading counterforce, and the tool can be held axially between the contact piece and the counterforce.
When the heating of the tool receptacle is performed with the opening of the tool receptacle increased due to the warning, the tool penetrates with its shaft into the larger opening of the tool receptacle. This insertion movement is performed because of the vertical arrangement under the action of the gravity forces. It can be also performed with the vertical arrangement and also with another spacial orientation of the arrangement manually and/or by driven means and/or by an adjustment drive, etc. The insertion of the tool clamped in the above mentioned manner, into the opening of the tool receptacle is stopped when the nominal value provided by adjustment is achieved. This stopping can be obtained by mechanical abutting against an abutment or in a similar way. When subsequently the heating is stopped, the tool receptacle is cooled and the tool shaft is clamped in a force-transmitting manner in the opening which is shrunk by cooling.
The method in accordance with the present invention is applicable equally for tools with low thermal expansion and for tools with high thermal expansion, so that both the tools of hard metal, ceramic and the like as well as tools composed for example of tool steel can be utilized. It should be taken into consideration that the heating phase is very short and as a rule is only approximately 5-10 seconds, and the adjustment o
Sandkuehler Olaf
Voss Michael
Bilz Werkzeugfabrik GmbH & Co. KG
Bryant David P.
Striker Michael J.
LandOfFree
Method for force-transmitting clamping of a tool does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for force-transmitting clamping of a tool, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for force-transmitting clamping of a tool will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3199503