The hottest three side positioning tool handle imp

2022-08-11
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Three sided positioning tool handle improves cutting stability

the spindle speed of the machine tool is undoubtedly gradually increasing, and please see the comparison between the standard speed of the machining center five years ago and today. Due to the extremely high speed, the sensitivity to the dynamic changes of the tool handle and the spindle connecting end is also increasing

when rotating at high speed, the spindle taper hole of general machine tools tends to be slightly enlarged under the action of centrifugal force. The ordinary V-groove tool holder only contacts the taper hole of the spindle. Under the condition of dynamic machining, the tool holder moves axially, which changes the tool positioning benchmark usually set as a fixed value. In this way, the cutting accuracy will be affected

Nikken kosakusho works company in Osaka, Japan has developed a "3-lock" or three-sided positioning tool handle, which overcomes the shortcomings of the conventional V-groove taper handle under the condition of high-speed rotation

in order to solve the problem of spindle "bell mouth" (sometimes referred to as "spindle taper hole opening"), a more common method is to design a tool handle structure that contacts both the spindle taper hole and the spindle nose. Contact on both sides can keep the tool handle fixed in the radial and axial direction, forming a relatively rigid connection

the contact between the tool handle and the nose flange of the spindle prevents the tool handle from further extending into the spindle hole when rotating at high speed. In addition, the simultaneous contact between the conical surface and the end face also helps to prevent the tool handle from deforming under the action of cutting force

Figure 1: Nikken three sided positioning tool handle uses the preloaded taper sleeve to press the tool handle into the spindle hole,

it can be seen that there is a seam on the taper sleeve that is convenient for the movement of the taper sleeve. The high-speed centrifugal force causes the spindle orifice to expand, and the

preload cone sleeve expands, keeping the tool handle in close contact with the spindle hole

among the tool handles with double contact between end face and conical surface, the most popular is probably HSK series short cone hollow handle. The Nikken tool handle provides the machining workshop with a choice - they can choose the existing V-groove tool handle or choose the three side positioning tool handle. HSK tool handle is not the case, it excludes any tool handle form other than HSK

in addition, the three sided positioning tool handle uses the spring mechanism to realize the contact between the conical surface and the end face, so that the conical handle can be reliably pushed into the main shaft hole, and can compensate the dynamic deformation of the main shaft hole under the action of centrifugal force. The spring mechanism is composed of a cone sleeve and an integral cone core like a conventional V-groove knife handle

the taper sleeve has an axial slot, which is often made of ordinary carbon steel such as Q235 or Q275, so that the taper sleeve can move regardless of the taper core. There is a disc spring between the slotted conical sleeve and the conical flange. After the pull rod pulls the knife handle into the spindle hole, the disc spring is compressed, which preloads the conical sleeve, causing the whole conical handle to be in full contact with the spindle hole

after the tool handle is inserted into the spindle hole of the machine tool, the electronic processing is usually left between the spindle end face and the top of the tool handle flange. There is a 4mm gap on the 2D plane, while the Nikken tool handle increases the allowance of 2mm, and the remaining gap is filled with precision machined adjusting shims

Figure 2: this figure shows the reason for the "three lock" or "three side positioning" mode. In the process of high-speed operation, he said: Although our composite decoration looks more like solid wood

the preloaded cone sleeve expands, so that the knife handle and the spindle hole maintain conical contact. The third contact point is the contact between the spindle nose and the handle flange

the gap between the tool handle flange and the spindle nose is compensated by precision machined adjusting shims

first use the plug gauge provided by Nikken to accurately measure the gap, and then install the gasket in place to make up for the gap and make the end face of the spindle contact the tool handle. The gap between different spindles is actively marching towards the blue ocean of the industry, and the deviation is bridged by this method

after the tool handle is pulled into the spindle hole by the pull rod, the taper sleeve will press against the taper hole under the action of the spring. Once the handle flange contacts the spindle nose, the action of the pull rod stops, but its total tension remains unchanged, no matter how fast the spindle speed is

at this time, the taper sleeve of the tool handle remains under pressure. When the speed of the spindle increases and the spindle hole begins to "flare" deformation, the taper sleeve expands to compensate for the deformation of the spindle hole and maintain the contact between the spindle taper hole and the tool handle. As a result, a relatively stable connection is formed under dynamic cutting conditions

because the tool handle contacts with the spindle nose, the tool handle body cannot continue to extend inward with the enlargement of the spindle orifice, so as to ensure that the tool handle positioning fern is fixed and achieve high accuracy

according to the company, the coil spring forms a damping zone at the bottom of the cone sleeve, which acts like a damping pad. The damping effect makes the tool handle absorb the vibration and slight deflection generated during cutting, so the cutting tool can increase the speed, and the machine tool itself can also prolong its life

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