ELECTRODE TOOL-HOLDER AND MACHINING METHOD OF SPROCKET SOCKET TECHNICAL FIELD 5 The present disclosure mainly relates to the technical field of non-traditional machining, and more particularly to an electrode tool-holder and a machining method of a sprocket socket. BACKGROUND 10 Any discussion of the background art throughout the specification should in no way be considered as an admission that such background art is prior art nor that such background art is widely known or forms part of the common general knowledge in the field in Australia or worldwide. Currently, most sprocket sockets of mining scraper conveyors are machined 15 by numerical-control boring and milling machines. But the traditional numerical-control machining has these defects, such as large consumption of tools, low efficiency in milling and cutting, and high cost in machining. As mining enterprises need more and more extra-heavy scraper conveyors, the matched sprockets become bigger and bigger in size, alloy steel of high hardness and high 20 wear-resistance is adopted more and more. Thus higher requirement is raised to the machining of sprocket sockets. Therefore, multiple sprocket sockets can't be machined at the same time and the efficiency is very low with the existing machining method of sprocket sockets, which can't meet the increasing demand of manufacturing enterprises for 25 manufacturing efficiency, quality and cost. SUMMARY Throughout this specification, unless the context requires otherwise, the words "comprise", "comprises" and "comprising" will be understood to imply the 1 inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements. Any one of the terms: "including" or "which includes" or "that includes" as used herein is also an open term that also means including at least the 5 elements/features that follow the term, but not excluding others. Thus, "including" is synonymous with and means "comprising". It is an object of the present invention to overcome or ameliorate at least one or more of the disadvantages of the prior art, or to provide a useful alternative. According to a first aspect, there is provided an electrode tool-holder. The 10 electrode tool holder may comprise a chuck body, whose center has a through hole used to place a sprocket. The electrode tool holder may further comprise multiple chuck-adjusting holes, each of which locates on the side edge of the chuck body and matches with a jaw. The electrode tool holder may further comprise multiple jaws, which locate on the radial end-face of the chuck body. The electrode used to 15 machine the sprocket socket may be fixed to the end edge of every jaw whose end face directly faces the center of the through hole. According to a particular arrangement of the first aspect, there is provided an electrode tool-holder, comprising: a chuck body, whose center has a through hole used to place a sprocket; multiple chuck-adjusting holes, each of which locates on 20 the side edge of the chuck body and matches with a jaw; multiple jaws, which locate on the radial end-face of the chuck body, wherein electrode used to machine sprocket socket is fixed to the end edge of every jaw whose end face directly faces the center of the through hole. The electrode tool holder may further comprise an electrode head and an 25 electrode handle. A radial locating slot may be slotted on the end-face surface of each jaw directly facing the center of the through hole. Each electrode head directing may face the center of the through hole. The electrode handle may be fixed in the locating slot. 2 The electrode tool holder may further comprise multiple electrode holders which may be fixed to the end-face of each jaw which may directly face the center of the through hole. The multiple electrode holders may be used to install the electrodes. 5 The surface of each electrode holder whose back towards the corresponding jaw slots a radial locating slot. The electrode head of each electrode may directly face the center of the through hole. The electrode handle may be fixed in the locating slot. According to a second aspect there is provided a machining method of 10 sprocket socket adopting the electrode tool-holder of the first aspect. The method may comprise fixing the electrode tool-holder to the workbench of an electrical discharge machine. The method may further comprise fixing the sprocket with tooth profile in the through hole which is in the center of the chuck body. The middle of each sprocket-tooth profile may directly face each electrode of the 15 electrode tool-holder. All sprocket-tooth profiles may be machined by a control system of an electrical discharge machine at the same time. Sprocket sockets may be obtained after machining. According to a particular arrangement of the second aspect there is provided a machining method of sprocket socket adopting the electrode tool-holder of the 20 first aspect, comprising: fixing the electrode tool-holder to the workbench of an electrical discharge machine; fixing the sprocket with tooth profile in the through hole which is in the center of the chuck body, and the middle of each sprocket-tooth profile directly faces each electrode of the electrode tool-holder; wherein all sprocket-tooth profiles are machined by a control system of an electrical discharge 25 machine at the same time; sprocket sockets are obtained after machining. The electrode's quantity of an electrode tool-holder may be no less than the quantity of sprocket-tooth profiles. The sprocket may be fixed in the through hole which is in the center of the chuck-body by the location clamping device fixed on the workbench. 3 In one aspect, the present disclosure relates to an electrode tool-holder. In order to disclose basic understanding of some aspects of some embodiments, briefness is provided here below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be 5 used to limit the scope of the claimed subject matter, which is as a preface of specification hereinafter by giving some concepts in a brief way. In certain embodiments, the electrode tool-holder includes a chuck body whose center has a through hole used to place a sprocket. The chuck has multiple chuck-adjusting holes on its side edge and every chuck-adjusting hole matches with 10 a jaw. There are multiple jaws on the radial end-face of the chuck body. Electrode used to machine sprocket socket is fixed to the end edge of every jaw whose end face directly faces the through-hole center. In certain embodiments, the electrode of the electrode tool-holder includes an electrode head and an electrode handle. 15 In some optional embodiments, a radial locating slot is slotted on the end-edge surface of a jaw directly facing the through-hole center. Each electrode head directing faces the center of the through hole. The electrode handle is fixed in the locating slot. In another aspect, the present disclosure relates to a machining method of a 20 sprocket socket. In some optional embodiments, the machining method includes the following steps: fix electrode tool-holder to the workbench of an electrical discharge machine; fix the sprocket with tooth profile in the through hole which is in the centre of the chuck body, and the middle of each sprocket-tooth profile directly 25 faces each electrode of the electrode tool-holder after fixing; all sprocket-tooth profiles are machined by the control system of the electrical discharge machine at the same time; sprocket sockets are obtained after machining. In some optional embodiments, the electrode's quantity of an electrode tool-holder is no less than the quantity of sprocket-tooth profiles. 4 In some optional embodiments, the sprocket is fixed in the through hole of the chuck-body center by the location clamping device fixed on the workbench. By contrast with the existing technology, this present disclosure has these advantages as below: 5 This disclosure provides an electrode tool-holder and a machining method of a sprocket socket. With the machining method, all sockets of a sprocket are machined at the same time, so that the machining efficiency is raised. Meanwhile, it can avoid the consumption of traditional machining tools and improve economic benefits that alloy of high hardness can be machined via the electrical discharge of 10 tool electrodes of lower hardness. For the above described and the related purpose, the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which one or more exemplary embodiments of this disclosure are shown. These and other aspects of the present disclosure will become apparent 15 from the following description of the example embodiment taken in conjunction with the following drawings, although variations and modifications therein may be effected without departing from the spirit and scope of the novel concepts of the disclosure. Other features, details, utilities, and advantages of the present disclosure will be apparent from the following more particular written description of 20 various embodiments of the invention as further illustrated in the accompanying drawings and defined in the appended claims. BRIEF DESCRIPTION OF FIGURES FIG. 1 is the structure drawing of an electrode tool-holder according to an 25 embodiment of the present disclosure; FIG. 2 is the structure drawing of an electrode tool-holder according to an embodiment of the present disclosure; and FIG. 3 is the flowchart of the machining method of sprocket sockets according to an embodiment of the present disclosure. 5 DETAIL DESCRIPTION The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the 5 disclosure are shown, so that those skilled in the art can realize them. The embodiments just present possible changes, a single part and function are selectable, and also the operation order can be changed. Parts and technical features of some embodiments may be included in or replaced to other embodiments. This disclosure may, however, be embodied in many different 10 forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like elements throughout. The scope of the embodiments of the present disclosure not only includes the scope of its claims, 15 but also includes all equivalents obtained from the claims. In this text, these embodiments may be described as "invention" singly or generally, which is just for convenient to express, but the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. 20 The present disclosure will be described in detail with reference to the accompanying drawings. FIG. 1 is the structure drawing of an electrode tool-holder according to an embodiment of the present disclosure. As shown in FIG. 1, an electrode tool-holder is provided in some optional embodiments. The electrode tool-holder includes a chuck body 1 whose center 25 has a through hole 3 used to place a sprocket 2. The chuck body 1 has multiple chuck-adjusting holes 4 on its side edge and every chuck-adjusting hole matches with a jaw. There are multiple jaws 5 on the radial end-face of the chuck body 1. Electrodes 6 used to machine sprocket 2 are fixed to the end face of each jaw whose end face directly faces the center of the through hole 3. In the process of 6 machining, while the chuck body 1 is rotated by rotating a chuck wrench in a chuck-adjusting hole 4, a jaw 5 and electrode 6 will be driven towards or away from the through hole 3. In some optional embodiments, the electrode 6 of the electrode tool-holder 5 includes an electrode head 7 and an electrode handle 8. In some optional embodiments, a radial locating slot 9 is slotted on the end-face surface of each jaw 5, whose end-face surface directly faces the center of the through hole 3. Each electrode head 7 of the electrodes 6 directing faces the center of the through hole 3, and the electrode handle 8 is fixed in the locating slot 10 9. FIG. 2 is the structure drawing of an electrode tool-holder according to an embodiment of the present disclosure. As shown in FIG. 2, in the process of machining, the end thread 11 of the chuck body 1 is controlled and driven by a servo motor 10 with a bevel gear head 15 which passes through the through hole 3, in order to control the feed automatically and drive all the jaws 5 and electrodes 6 towards or away from the through hole 3 at the same time. FIG. 3 is the flowchart of machining method of sprocket sockets according to an embodiment of the present disclosure. 20 As shown in FIG. 3, a machining method of sprocket sockets is provided in some optional embodiments, and the method includes the following steps: S31: Fix the electrode tool-holder to the workbench of an electrical discharge machine. In some embodiments, the quantity of electrodes is decided by the quantity 25 of sprocket sockets to be machined and is no less than it. S32: Fix the sprocket with tooth profile in the through hole of the chuck-body center, and the middle of every sprocket-tooth profile directly faces every electrode of the electrode tool-holder correspondingly. In some optional embodiments, the sprocket is fixed in the through hole of 7 the chuck-body center via the location clamping device fixed on the workbench. S33: All the sprocket-tooth profiles of the sprocket are machined by the control system of an electrical discharge machine at the same time; sprocket sockets are obtained after machining. 5 With the machining method, that all sockets of a sprocket are machined at the same time raises the machining efficiency. Meanwhile, it can avoid the consumption of traditional machining tools and improve economic benefits that alloy of high hardness can be machined via the electrical discharge of tool electrodes of lower hardness. 10 The foregoing description of the exemplary embodiments of the disclosure has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. 8