Clamping Holder Four-Point Insert Stability
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Solution Overview
Problem
Conventional clamping holders for cutting inserts often fail to securely hold the insert under high cutting forces, leading to tilting, detachment, vibrations, and premature wear due to inadequate contact points and torque resistance.
Innovation Solution
A clamping holder design featuring a stop surface angled between 15 and 50 degrees relative to the insertion direction, acting as a fourth contact point and limiting insertion depth, along with a U-shaped recess with concave and convex sides to enhance stability and torque resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional three-point contact holder is used, then the structure is simple, but the torque resistance is insufficient under high cutting forces
Solution Approach 1:
The single contact surface on the rigid holding part is segmented into two separate contact points spaced apart from each other. This segmentation increases the lever arm distance between contact points, thereby enhancing torque resistance without adding complex external structures. The cutting insert's bottom surface is similarly segmented with two corresponding contact surfaces that engage with the spaced contact points on the holder.
2Reliability
If the cutting insert protrudes slightly from the tool holder, then the cutting edge can contact the workpiece first, but high forces cause tilting and detachment
Solution Approach 1:
The clamping finger is designed with elastic mobility that allows preliminary insertion of the cutting insert without full clamping force. The insert can be easily inserted while the clamping finger is in its unclamped, more open position. Once inserted, the clamping finger is actuated to engage the insert's contact surfaces, providing secure positioning before machining begins.
Solution Approach 2:
The clamping finger transitions from a static rigid structure to a dynamic elastic element that can move relative to the rigid holding part. This elasticity allows the clamping mechanism to adapt during insertion and provide controlled clamping force, improving both ease of operation and positioning reliability.
3Manufacturing precision
If a stop is provided to limit insertion depth, then the insert position is controlled, but the stop may not effectively resist torque with conventional designs
Solution Approach 1:
The stop surface on the rigid holding part is designed with an asymmetric angle relative to the cutting insert's rear surface. This angled asymmetric configuration creates a mechanical advantage where the stop surface not only limits insertion depth but also provides torque resistance by distributing forces across the angled contact area, preventing the insert from tilting or detaching under cutting loads.
Data Source
Figure 1~3
Figure 2
Figure 4a~4b
AI summary
The present invention relates to a clamping holder (10) for cutting inserts (20), having a rigid holding part (1) and a clamping finger (2) that is elastically movable with respect to the rigid holding part (1), wherein the holding part (1) and the clamping finger (2) define opposite sides of a substantially U-shaped recess (3) for receiving a cutting insert (20), wherein one of these two sides has first and second spaced-apart contact points for one side of a cutting insert and the opposite side has a third contact point, and wherein a stop (7) for limiting the insertion depth of the cutting inset (20) into the recess (3) is provided inside the recess (3). In order to create a corresponding clamping holder for cutting inserts, and also a suitable cutting insert, which are capable of withstanding relatively large cutting forces, of ensuring a stable and secure position of the cutting insert in the clamping holder even under difficult conditions, i.e. in the event of high cutting forces, and of reducing vibrations and thus even premature wear of the cutting insert during workpiece machining, it is proposed according to the invention that that side of the cutting insert that has the third contact point is additionally assigned the stop, which is configured such that it simultaneously acts as a further, fourth lateral contact point opposite the first and second contact points and as a stop for limiting the insertion depth of the cutting insert.