Parafusos para fixação de insertos

Current Journal of Applied Science and Technology[pic 1]

38(3): 1-7, 2019; Article no.CJAST.52272

ISSN: 2457-1024

(Past name: British Journal of Applied Science & Technology, Past ISSN: 2231-0843, NLM ID: 101664541)[pic 2]

Specialized Screw for Clamping of Cutting Tool

Inserts

Karol Vasilko1 and Zuzana Murčinková1*

1Faculty of Manufacturing Technologies, Technical University of Košice, 080 01 Prešov, Bayerova 1,

SR, Slovakia.

Authors’ contributions

This work was carried out in collaboration between both authors. Author KV designed the clamping screw and realized practical applications and testing. Author ZM managed the literature searches and analytical and numerical calculations. Both authors read and approved the

final manuscript.

Article Information

DOI: 10.9734/CJAST/2019/v38i330359

Editor(s):

1. Dr. Rodolfo Dufo Lopez, Professor, Department of Electrical Engineering, University of Zaragoza, Spain.

Reviewers:

1. Shashidhar K. Kudari, CVR College of Engineering, India.
2. Shpetim Rexhepi, Mather Theresa University, India. Complete Peer review History: http://www.sdiarticle4.com/review-history/52272

Received 12 August 2019

Accepted 18 October 2019[pic 3]

Published 25 October 2019

[pic 4]

ABSTRACT

[pic 5]

Keywords: Cutting tool insert; clamping; axial force; screw head; contact.

[pic 6]

*Corresponding author: E-mail: [e-mail];

1. INTRODUCTION

Each producer of cutting tool inserts provides the various designs of clamping in cutting tool holder to obtain precise and stabile connection when machining. Mainly, the clamping mechanisms are based on mechanical connection using  mainly the screw/s [1-3]. The screw connection can be placed either visibly, i.e. outside, the tool holder, or inside its body when the screw head is protected from forming chips and cutting fluids. The most important property of clamping is its stiffness given by stiffness of screw and thus its reliability [4]. The simplicity and speed of assembling and disassembling are other important properties. In present, it is very important to choose the tool clamping system which adapts to conditions of e.g. the high speed machining [5] or the cryogenics temperatures [6].

Fig. 1 presents selected patents of clamping devices for cutting inserts from 2008-2013. Each mechanism  is  of  more   or  less  complicated

---

design. In Fig. 1, A, the clamping device [7] has two clamping elements (screws) perpendicular to each other. Next technical design [8] (Fig. 1B) needs oblique hole difficult for drilling and special screw. The clamping device [9] (Fig.  1C) intended for cutting-off avoids the screw joint, however it involves special additional device to the opening position for insertion or removal of an insert. Patents [10] (Fig.  1D) and [11] (Fig. 1E) are of similar principle involving the component for tangential contact with inner wall of insert by screw pressure. Mentioned designs need complex shape features either inside tool holder or special elements as separately part of tool holder.

The technical solution presented in paper provides considerable increase in clamping stiffness by use of only one component and, moreover, self-locking clamping using the friction force between the clamping screw head  and quite large contact area between screw head and insert.

[pic 7] [pic 8] A	[pic 9] B
[pic 10] C	[pic 11] D	[pic 12] E

Fig. 1. Selected patents of clamping devices

1. DESCRIPTION OF TECHNICAL DESIGN

---

b. Next tightening causes bending of screw shaft

and deformation  od  specialized  screw  head.

The technical solution of the cutting tool inserts clamping is based on the application of one

---

Thus, the surface of the screw head contacts the upper flat surface of the cutting insert and locks

specialized        clamping        screw        of

---

hexagonal-

---

insert in seating by the friction force – phase c.

conical        shaped        head        with        metric        thread        An  inclined   surface   of   tool   holder   causes

along  screw  shaft  and  the  axis

---

perpendicular

---

increased  contact  pressure  and

---

contact  area.

to  the  upper  surface  of  cutting  tool   insert (Fig. 2). The screw is of normalized  metric thread.

---

Phase d is un-wanted phase when the screw is over-tightened and contact is not appropriate. Theoretically, the screw can even achieve plastic deformation.

The phases of cutting-tool insert clamping are

shown in Fig. 3. The bolthole in tool holder body is in vicinity of insert so that the screw head can contact insert from above. The axis of bolthole is perpendicular to the upper and lower tool holder

---

The final clamping occurs in the phase c with the planar contact between the screw head and the insert surfaces. At the same time, the cutting tool insert is being pressed into the seating by the