Cutting – Tool or tool with support – Joint or connection
Reexamination Certificate
2000-03-09
2001-08-28
Rada, Rinaldi I. (Department: 3724)
Cutting
Tool or tool with support
Joint or connection
C083S663000
Reexamination Certificate
active
06279444
ABSTRACT:
The invention relates to a cutting tool, in particular a planing cutter head or planing cutter spindle, with a supporting body having at least one receptacle open radially outward, a wedge-shaped clamping jaw arranged in the receptacle, and a cutter able to be gripped in its seat by means of the clamping jaw, in connection with which the clamping jaw is prestressed by a pressure spring to position the cutter and can be slid radially inward against the force of the pressure spring to remove the cutter, and the clamping jaw can be locked in its radially inward position.
Such a cutting tool is known from EP 0 428 996 B1, for example. To lock the clamping jaw, a recess is incorporated in the receptacle in the supporting body on the side opposite the cutter seat; the clamping jaw can snap into this recess with a projection provided on it. When changing cutters, the clamping jaw must be pressed radially inward and tilted slightly in its inward position so that the projection on the supporting body can engage the recess in the supporting body and so that the clamping jaw can be locked.
To release the clamping jaw, it must first be lowered a bit more and then tipped back in the other direction, in order for the projection to disengage the recess in the supporting body. The combined pressure and tipping motion a certain manual skill is required when changing cutters.
A cutter spindle is known from DE-AS 11 95 934. The cutter is screwed down with a cutter holder that can be attached form-fitting in a recess in the supporting body. The cutter holder is impacted from the rear by the spring-loaded clamping jaw, thereby positioning the cutter on its trajectory circle. If the cutter spindle is rotated, as a result of the centrifugal force acting on the clamping jaw the clamping jaw moves radially outward in the receptacle and solidly clamps the cutter via the cutter holder. To change the cutter, the operator must press the clamping jaw radially inward against the force of the spring and hold it in this position until the cutter holder can be released from the form closure and removed together with the cutter. The clamping jaw must then be slowly released in such a way that it is pushed radially outward by the pressure spring. If the clamping jaw is let go too quickly, the spring springs out suddenly and flings the clamping jaw out of the receptacle. In this case there is considerable risk of injury for the operating personnel. Since the clamping jaw can also fall out of the receptacle—and then possibly could not be found—the operator will remove the clamping jaw when changing the cutter, as a rule. Consequently, handling the cutting tool is quite complicated.
Similar cutting tools are also known from the German utility model no. 72 34 252 and [patent] DE 25 59 406 A1. In the case of the cutting tool according to the latter publication, the cutter is connected via a spring/groove connection with a cutter holder that protrudes into the groove-shaped receptacle; the spring-loaded clamping jaw acts against the rear of the cutter holder. The cutter holder is likewise stressed by a pressure spring. The cutter is positioned by the prestressed cutter holder and the prestressed clamping jaw. If the cutter spindle is rotated, as a result of the centrifugal force acting on the clamping jaw the clamping jaw moves radially outward in the receptacle and solidly clamps the cutter via the cutter holder.
To remove the cutter, the clamping jaw must be pressed back radially inward against the spring force until its locking with the cutter holder is released, whereby the cutter holder with the cutter is then pushed further radially outward by the pressure spring acting on it, and the cutter can then be removed from the cutter holder. If the clamping jaw is relieved, it springs back in the receptacle and hits against the cutter holder in the removal position. If the new cutter is to be positioned, the cutter holder must be pressed back not only against the force of its pressure spring but additionally against the frictional force acting on it from the clamping jaw. If the frictional force is too great, the clamping jaw must again be pressed radially inward and held there until the cutter holder has been brought into its position; this in part causes very complicated handling of the cutting tool.
Starting with this set of problems, the cutting tool described in the beginning is to be improved in such a way that to change the cutter, the locking of the clamping jaw in its radially inward position is made easier.
As a solution, the generic cutting tool is characterized in that to automatically lock the clamping jaw, a spring-loaded bolt is provided that engages a recess provided in the clamping jaw. With this design, it is also possible, as previously, to slide the clamping jaw radially inward into the receptacle against the force of the pressure spring to remove the cutter. If slid far enough, the clamping jaw snaps tight. The cutter can then be removed and also reinserted without the clamping jaw having to be pressed in or tipped again by the operator in the process.
The bolt is preferably arranged essentially tangentially in the supporting body and is guided in a bore in the supporting body, ending in the receptacle. If the clamping jaw is pressed far enough into the receptacle, the bolt snaps into the recess preferably designed as a bore hole, whereby a secure attachment and locking of the clamping jaw is brought about.
To release the locking of the clamping jaw, a bolt hole is preferably provided in the supporting body that is aligned with the bolt hole of the clamping jaw and ends in the receptacle. A tool (mandrel) can then be inserted into this bore hole and the bolt can be pressed back into its guide bore. The clamping jaw then springs back a little and blocks the bolt in its guide bore. After the tool is pulled out, the clamping jaw springs further radially outward and then positions the cutter.
If the clamping jaw is designed with a symmetric cross-section, it is effectively prevented from being accidentally inserted the wrong way into the receptacle, thereby increasing safety during operation of the cutting tool.
A cutter holder is preferably arranged between the clamping jaw and the cutter; in particular it is preferably mounted pivoting in the receptacle. In the radially inward position of the clamping jaw, the cutter holder then swings back, thereby simplifying the removal of the cutter. At the same time, the insertion of a new cutter is also made easier. If the clamping jaw springs back, the cutter holder swings against the cutter and the cutter is positioned. In order to set the precise positioning, the cutter can be connected form-fitting with the cutter holder via a spring/groove connection. The cutter holder is prestressed by a pressure spring resting against the bottom of the receptacle in such a way that it presses the cutter holder radially outward after the clamping jaw is released, until the cutter holder is pressed radially outward against a stop provided in the receptacle. In this way, the diameter of the cutter's trajectory circle is set precisely.
The cutter holder is then prestressed via a bolt that has a stud projecting radially outward and against which the clamping jaw hits, and when the latter is locked, it pushes the bolt far enough radially inward that the cutter holder is relieved of force.
To secure the cutter axially, at least one screw, able to be screwed axially into the supporting body, can be provided. This design prevents the cutter from falling axially out of the cutter spindle when changing the cutter on cutting tools that are vertically inserted into the machine.
To secure the cutter holder axially, a bushing can be inserted into the bore hole in the supporting body; with its end facing the receptacle, it engages a recess in the cutter holder. In this way, the cutter holder is secured axially.
If, in the clamping jaw, a groove is provided that ends in the recess and can be engaged by the bolt when the clamping jaw takes its radially outward position, th
Kellner Karl-Heinz
Stein Dieter
Leitz GmbH & Co. KG
McGuireWoods LLP
Rada Rinaldi I.
Tran Kim Ngo C
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