Patent Description:
At present, a lathe or a miller is generally used for machining a ring groove on an internal rotation surface of a workpiece with an internal rotation hole. However, this conventional machining method is generally time consuming, and requires a highly rigid machining tool.

In addition, especially when the internal rotation hole of the workpiece is a non-centrosymmetric hole, in a machining procedure, because end faces of the internal rotation hole is asymmetric, stress exerted on a cutting tool that is in contact with the end faces is uneven, generating vibration. Further, different levels of rippling are generated on a ring surface of a machined ring groove, affecting roughness of the ring surface of the machined ring groove and affecting machining quality.

Therefore, it is necessary to provide an improved machining apparatus and machining method to resolve at least one of the foregoing problems. <CIT> discloses a tool for milling or cutting pipes in undersea boreholes.

An aspect of the present invention provides an apparatus for electrical machining according to claim <NUM>.

Another aspect of the present invention provides a method for electrical machining according to claim <NUM>.

The apparatus for electrical machining and the method for electrical machining according to specific embodiments of the present invention are simple, easy to implement, and cost effective.

You can get better understanding of these and other characteristics, aspects, and advantages of the present invention with reference to the accompanying drawings when reading the following detailed descriptions. In the accompanying drawings, the same element reference numbers are used to denote the same parts in all the accompanying drawings.

To help persons skilled in the art to clearly understand the protection scope of the present invention, the following describes specific embodiments of the present invention with reference to the accompanying drawings. In the following detailed descriptions of the specific embodiments, this specification does not describe some commonly known functions or structures, to prevent unnecessary details from affecting the disclosure of the present invention.

Unless otherwise defined, technical terms or scientific terms used in the claims and the specification should be ordinary meanings understood by persons of ordinary skill in the art of the present invention. "First", "second", and similar words used in the specification and the claims do not denote any order, quantity, or importance, but are merely used to distinguish different components. "A" or "an" and similar words do not constitute a limitation on a quantity, but indicate the presence of at least one. "Connect" or "connected" and similar words are not limited to a physical or mechanical connection, but may include an electropolar connection, either direct or indirect. Moreover, the term "based on" refers to "at least partially based on".

It should be noted that, in the accompanying drawings of the present invention, to make illustrations and elements clearly visible, elements in some of the accompanying drawings are not marked by section lines.

<FIG> are schematic diagrams of an apparatus <NUM> for electrical machining according to a first specific embodiment of the present invention. <FIG> are schematic diagrams of the apparatus <NUM> for electrical machining before a rotatable shaft <NUM> of the apparatus <NUM> is rotated. <FIG> are schematic diagrams of the apparatus <NUM> for electrical machining after the rotatable shaft <NUM> of the apparatus <NUM> is rotated. As shown in <FIG>, the apparatus <NUM> for electrical machining according to the first specific embodiment of the present invention includes the rotatable shaft <NUM> and an electrode <NUM> for electrical machining. The rotatable shaft <NUM> has a rotation axis <NUM>. The electrode <NUM> includes a first electrode <NUM> and a second electrode <NUM>. The first electrode <NUM> and the second electrode <NUM> may be movably connected to the rotatable shaft <NUM>. In addition, the first electrode <NUM> and the second electrode <NUM> are symmetrically disposed relative to the rotation axis <NUM> of the rotatable shaft <NUM>, that is, the first electrode <NUM> and the second electrode <NUM> are evenly distributed on the rotatable shaft <NUM>. As shown in <FIG>, when the rotatable shaft <NUM> is rotated, the first electrode <NUM> and the second electrode <NUM> can rotate together with the rotatable shaft <NUM> around the rotation axis <NUM> of the rotatable shaft <NUM>. Moreover, the rotatable shaft <NUM> is rotated to generate centrifugal force. The first electrode <NUM> and the second electrode <NUM> can translate far away from each other relative to the rotatable shaft <NUM> under an action of the centrifugal force, that is, move in parallel towards opposite directions. In addition, a moving distance (not marked) of the first electrode <NUM> and the second electrode <NUM> can be controlled based on a rotary speed of the rotatable shaft <NUM>.

As shown in <FIG>, in a specific embodiment, an elastic element, for example, a spring <NUM>, is connected between the first electrode <NUM> and the second electrode <NUM>. Under an action of elastic force of the spring <NUM>, the first electrode <NUM> and the second electrode <NUM> are positioned relative to the rotatable shaft <NUM>. In an optional specific embodiment, the first electrode <NUM> and the second electrode <NUM> may also be separately positioned relative to the rotatable shaft <NUM> by using two independent springs of their own.

In a specific embodiment, the rotatable shaft <NUM> is provided with an accommodation space <NUM> for accommodating the first electrode <NUM> and the second electrode <NUM>. Moreover, the first electrode <NUM> and the second electrode <NUM> are movable in the accommodation space <NUM>. As shown in <FIG>, before the rotatable shaft <NUM> is rotated, the first electrode <NUM> and the second electrode <NUM> can be accommodated in the accommodation space <NUM> of the rotatable shaft <NUM>, thereby reducing a size of the apparatus <NUM> for electrical machining and playing an effect for protecting the first electrode <NUM> and the second electrode <NUM>. As shown in <FIG>, after the rotatable shaft <NUM> is rotated, the first electrode <NUM> and the second electrode <NUM> can translate, relative to the rotatable shaft <NUM>, far away from each other in the accommodation space <NUM> under the action of the centrifugal force. The apparatus <NUM> for electrical machining according to the first specific embodiment of the present invention is not limited to providing the accommodation space <NUM> on the rotatable shaft <NUM>. In another optional or additional example, the first electrode <NUM> and the second electrode <NUM> may also be directly connected to an end or a side surface of the rotatable shaft <NUM>.

In a specific embodiment, the rotatable shaft <NUM> is provided with limiting portions <NUM> and <NUM>. The limiting portions <NUM> and <NUM> on the rotatable shaft <NUM> may be configured to limit maximum moving distances of the first electrode <NUM> and the second electrode <NUM> respectively. In this specific embodiment, the accommodation space <NUM> of the rotatable shaft <NUM> is provided with the limiting portions <NUM> and <NUM>. Correspondingly, the first electrode <NUM> and the second electrode <NUM> are provided with stoppers <NUM> and <NUM> respectively. When the first electrode <NUM> and the second electrode <NUM> separately move to the maximum moving distances of their own, the stoppers <NUM> and <NUM> of the first electrode <NUM> and the second electrode <NUM> cooperate with the limiting portions <NUM> and <NUM> of the rotatable shaft <NUM> respectively, so as to prevent the first electrode <NUM> and the second electrode <NUM> from continuing to move relative to the rotatable shaft <NUM>.

In a specific embodiment, the rotatable shaft <NUM> is movable along the rotation axis <NUM> of the rotatable shaft <NUM>. Therefore, by controlling movement of the rotatable shaft <NUM> along the rotation axis <NUM> (that is, axial movement), movement of the first electrode <NUM> and the second electrode <NUM> in a direction parallel to the rotation axis <NUM> of the rotatable shaft <NUM> (that is, axial movement) can be further controlled.

The apparatus <NUM> for electrical machining according to the first specific embodiment may use an electrical discharge machining (Electrical Discharge Machining, EDM) process, an electro-chemical machining (Electro-Chemical Machining, ECM) process, or an electro-chemical discharge machining (Electro-Chemical Discharge Machining, ECDM) process. The following uses the electrical discharge machining process as an example to describe the apparatus <NUM> for electrical machining according to the first specific embodiment. Certainly, it should be understood that, use of the electro-chemical machining process or the electro-chemical discharge machining process may be slightly different from use of the electrical discharge machining process. Such simple variations do not affect the innovation essence of the apparatus <NUM> for electrical machining according to the first specific embodiment of the present invention.

The rotatable shaft <NUM> is provided with a first passage <NUM> for transmitting a working fluid. The first electrode <NUM> and the second electrode <NUM> are respectively provided with a second passage <NUM> and a third passage <NUM> for transmitting the working fluid. The first passage <NUM>, the second passage <NUM>, and the third passage <NUM> are interconnected. By using the interconnected first passage <NUM>, second passage <NUM>, and third passage <NUM>, the working fluid can be transmitted to an area that the first electrode <NUM> and the second electrode <NUM> need to machine. However, in comparative examples a setting manner of the passages for transmitting the working fluid in the not limited thereto. In comparative examples another proper setting manner may also be used, as long as a passage setting can enable the working fluid to be transmitted to the area that the first electrode <NUM> and the second electrode <NUM> need to machine. Moreover, whether the used working fluid is electrically conductive or conductivity strength may be determined according to a machining process used by the apparatus <NUM> for electrical machining. For example, when the apparatus <NUM> for electrical machining uses the EDM process, the working fluid may be a dielectric fluid (Dielectric Fluid); when the apparatus <NUM> for electrical machining uses the ECM process, the working fluid may be an electrolyte (Electrolyte), and preferentially an electrolyte with strong conductivity; when the apparatus <NUM> for electrical machining uses the ECDM process, the working fluid may be an electrolyte with weak conductivity.

In a specific embodiment of the present invention, the apparatus <NUM> for electrical machining may be configured to machine a workpiece <NUM> with a hole <NUM>. As an example, the hole <NUM> of the workpiece <NUM> may be a rotation hole, as shown in <FIG>.

<FIG> are schematic diagrams of the apparatus <NUM> for electrical machining before the workpiece <NUM> is machined. With reference to <FIG>, when the apparatus <NUM> for electrical machining needs to machine the workpiece <NUM>, the rotatable shaft <NUM> of the apparatus <NUM> for electrical machining may be inserted into the hole <NUM> of the workpiece <NUM>, and certain gaps <NUM> and <NUM> are kept between the workpiece <NUM> and the first electrode <NUM> and the second electrode <NUM> respectively. Before the apparatus <NUM> for electrical machining machines the workpiece <NUM>, the first electrode <NUM> and the second electrode <NUM> remain in the accommodation space <NUM> of the rotatable shaft <NUM> under the action of the elastic force of the spring <NUM>. Moreover, in combination with <FIG>, before the workpiece <NUM> is machined, the hole <NUM> of the workpiece <NUM> has a first diameter D1.

<FIG> are schematic diagrams of the apparatus <NUM> for electrical machining during a procedure of machining the workpiece <NUM>. With reference to <FIG>, when the apparatus <NUM> for electrical machining machines the workpiece <NUM>, the first electrode <NUM>, the second electrode <NUM>, and the workpiece <NUM> are powered on, so that opposite electric polarities are carried between the first electrode <NUM> and the workpiece <NUM> and between the second electrode <NUM> and the workpiece <NUM>. Moreover, the rotatable shaft <NUM> is rotated in the hole <NUM> of the workpiece <NUM>. Rotation of the rotatable shaft <NUM> drives the first electrode <NUM> and the second electrode <NUM> to move together. The rotatable shaft <NUM> is rotated to generate the centrifugal force. The first electrode <NUM> and the second electrode <NUM> can translate, towards the workpiece <NUM>, far away from each other relative to the rotatable shaft <NUM> under the action of the centrifugal force. In this case, the spring <NUM> is extended. As the first electrode <NUM> and the second electrode <NUM> move, electrical discharges are generated between the first electrode <NUM> and the workpiece <NUM> that have opposite electric polarities and between the second electrode <NUM> and the workpiece <NUM> that have opposite electric polarities, so as to remove a portion of a material of the hole <NUM> of the workpiece <NUM>. Therefore, in combination with <FIG>, after the workpiece <NUM> is machined, a ring groove <NUM> is further formed in the hole <NUM> of the workpiece <NUM>. The ring groove <NUM> has a second diameter D2, that is, the hole <NUM> of the workpiece <NUM> has a second diameter D2 after machining. The second diameter D2 is greater than the first diameter D1. The ring groove <NUM> includes a cylindrical surface <NUM> that has the second diameter D2 and a flat surface <NUM>.

The apparatus <NUM> for electrical machining according to the first specific embodiment of the present invention has a simple structure and a low cost and is easy to implement. In addition, during the machining procedure, the first electrode <NUM> and the second electrode <NUM> can simultaneously move towards the workpiece <NUM>. Therefore, the electrical discharges can be simultaneously generated in the gap <NUM> between the first electrode <NUM> and the workpiece <NUM> and in the gap <NUM> between the second electrode <NUM> and the workpiece <NUM>, and the first electrode <NUM> and the second electrode <NUM> of the apparatus <NUM> for electrical machining can simultaneously perform machining on the workpiece <NUM>. Because the first electrode <NUM> and the second electrode <NUM> are symmetrically disposed relative to the rotation axis <NUM> of the rotatable shaft <NUM>, force exerted on the apparatus <NUM> for electrical machining is even during the entire machining procedure, thereby further improving surface machining flatness of the workpiece <NUM>.

The moving distance of the first electrode <NUM> and the second electrode <NUM> may be controlled based on the rotary speed of the rotatable shaft <NUM>, so as to control a size of the gap <NUM> between the first electrode <NUM> and the workpiece <NUM> and a size of the gap <NUM> between the second electrode <NUM> and the workpiece <NUM>. Moreover, a value of the second diameter D2 of the hole <NUM> of the workpiece <NUM> after machining may be controlled.

When the workpiece <NUM> is machined, the first passage <NUM>, the second passage <NUM>, and the third passage <NUM> that are interconnected among the rotatable shaft <NUM>, the first electrode <NUM>, and the second electrode <NUM> may supply the pressured working fluid to the area that the first electrode <NUM> and the second electrode <NUM> need to machine, and specifically to the gap <NUM> between the first electrode <NUM> and the workpiece <NUM> and the gap <NUM> between the second electrode <NUM> and the workpiece <NUM>. Therefore, during the procedure of machining the workpiece <NUM>, the pressured working fluid can flush through the machining area of the workpiece <NUM>. The flushing by the pressured working fluid can drain scraps generated during the machining procedure in time, thereby ensuring cleanness of the machining area of the workpiece <NUM>.

The rotation of the rotatable shaft <NUM> is properly controlled, so that the portion (that is, the ring groove <NUM>) that is obtained after material removing and that is of the hole <NUM> of the workpiece <NUM> has a complete cylindrical surface or a part of a cylindrical surface. In addition, because the rotatable shaft <NUM> is movable along the rotation axis <NUM> of the rotatable shaft <NUM>, the rotatable shaft <NUM> may be continuously controlled to move along the rotation axis <NUM> of the rotatable shaft <NUM>, thereby controlling a depth of the ring groove <NUM> in the direction parallel to the rotation axis <NUM> of the rotatable shaft <NUM> (that is, an axial depth). Further, the rotatable shaft <NUM> may be intermittently controlled to move along the rotation axis <NUM> of the rotatable shaft <NUM>, so that ring grooves <NUM> are distributed at an interval, and a plurality of ring grooves <NUM> distributed at an interval can be further obtained, by machining, in the hole <NUM> of the workpiece <NUM>. Therefore, rotation and axial movement of the rotatable shaft <NUM> may be properly controlled according to an actual need of the to-be-machined workpiece <NUM>.

<FIG> are schematic diagrams of a workpiece <NUM> according to a specific embodiment. As shown in <FIG>, in a specific embodiment of the present invention, an apparatus <NUM> for electrical machining may be configured to machine a regularly structured workpiece <NUM> that has a rotation hole <NUM>. With reference to <FIG>, before machining, the hole <NUM> of the workpiece <NUM> has a first diameter D1, and the hole <NUM> of the workpiece <NUM> is symmetric relative to a rotation central line. In an example, the apparatus <NUM> for electrical machining may start the machining from a middle part of the hole <NUM> of the workpiece <NUM>. Therefore, with reference to <FIG>, after the machining, a ring groove <NUM> may be further obtained by machining in the middle part of the hole <NUM> of the workpiece <NUM>. The ring groove <NUM> has a cylindrical surface <NUM> with a second diameter D2 and includes bottom and top flat surfaces <NUM>.

<FIG> are schematic diagrams of a workpiece <NUM>' according to another specific embodiment. As shown in <FIG>, in another specific embodiment of the present invention, an apparatus <NUM> for electrical machining may also be configured to machine an irregularly structured workpiece <NUM>' that has a rotation hole <NUM>. With reference to <FIG>, before machining, the hole <NUM> of the workpiece <NUM>' also has a first diameter D <NUM>, but the hole <NUM> of the workpiece <NUM>' is asymmetric relative to a rotation central line. For example, the hole <NUM> of the workpiece <NUM>' has an end with varied heights in a direction parallel to a rotation axis <NUM> of a rotatable shaft <NUM> (that is, an axial direction). In an example, the apparatus <NUM> for electrical machining may also start the machining from the end of the hole <NUM> of the workpiece <NUM>'. For example, in a case in which an electrode <NUM> includes a first electrode <NUM> and a second electrode <NUM>, the first electrode <NUM> and the second electrode <NUM> are pushed towards the end of the hole <NUM> in opposite directions under an action of centrifugal force, so as to remove at least a portion of a material of the end of the hole <NUM>. Therefore, with reference to <FIG>, after the machining, a ring groove <NUM> may be further obtained by machining at the end of the hole <NUM> of the workpiece <NUM>'. The ring groove <NUM> has a cylindrical surface <NUM> with a second diameter D2 and includes a bottom flat surface <NUM>. The hole <NUM> of the workpiece <NUM>' has the end with varied heights in the axial direction before the machining. Therefore, the ring groove <NUM> formed after the machining also has an end with varied heights in the axial direction.

<FIG> is a schematic block diagram of a system <NUM> for electrical machining during a procedure of machining a workpiece <NUM> according to a specific embodiment of the present invention. As shown in <FIG>, a system <NUM> for electrical machining according to a specific embodiment of the present invention includes the apparatus <NUM> for electrical machining according to the first specific embodiment of the present invention, a power supply <NUM>, a lathe <NUM>, a servo motor <NUM> disposed on the lathe <NUM>, and a working fluid supply apparatus <NUM>.

The power supply <NUM> includes a positive (+) lead <NUM> and a negative (-) lead <NUM>. In <FIG>, the positive lead <NUM> of the power supply <NUM> is shown as being connected to the to-be-machined workpiece <NUM>, so that the to-be-machined workpiece <NUM> carries positive electricity after the power supply <NUM> is started. The negative lead <NUM> of the power supply <NUM> is shown as being connected to a rotatable shaft <NUM> of the apparatus <NUM> for electrical machining. The rotatable shaft <NUM> is electrically connected to a first electrode <NUM> and a second electrode <NUM>, so that the rotatable shaft <NUM> may indirectly connect the negative lead <NUM> of the power supply <NUM> to the first electrode <NUM> and the second electrode <NUM> of the apparatus <NUM> for electrical machining. Therefore, the first electrode <NUM> and the second electrode <NUM> carry negative electricity after the power supply <NUM> is started. However, the present invention is not limited to that: the power supply <NUM> supplies negative electricity to the first electrode <NUM> and the second electrode <NUM>, and the power supply <NUM> supplies positive electricity to the workpiece <NUM>. In another specific embodiment of the present invention, it may also be that: the power supply <NUM> supplies positive electricity to the first electrode <NUM> and the second electrode <NUM>, and the power supply <NUM> supplies negative electricity to the workpiece <NUM>. Such a simple variation manner does not depart from the innovation essence of the present invention. In addition, the positive and negative leads <NUM> and <NUM> of the power supply <NUM> may also be connected to the first electrode <NUM>, the second electrode <NUM>, and the workpiece <NUM> in another proper manner. Actually, any connection manner of the power supply <NUM> that enables opposite electric polarities to be supplied between the first electrode <NUM> and the workpiece <NUM> and between the second electrode <NUM> and the workpiece <NUM> shall fall within the protection scope of the present invention.

The power supply <NUM> may communicate with the lathe <NUM>. The servo motor <NUM> disposed on the lathe <NUM> is configured to drive the rotatable shaft <NUM> of the apparatus <NUM> for electrical machining to rotate. The working fluid supply apparatus <NUM> is configured to: when the workpiece <NUM> is machined, supply a pressured working fluid to a gap <NUM> between the first electrode <NUM> and the workpiece <NUM> and a gap <NUM> between the second electrode <NUM> and the workpiece <NUM> by using a first passage <NUM>, a second passage <NUM>, and a third passage <NUM> that are of the apparatus <NUM> for electrical machining and that are interconnected with each other.

In a specific embodiment of the system <NUM> for electrical machining according to the present invention, the power supply <NUM> of the system <NUM> for electrical machining may further detect whether a short circuit occurs between the first electrode <NUM> and the workpiece <NUM> and between the second electrode <NUM> and the workpiece <NUM>. When the power supply <NUM> detects that a short circuit occurs, the power supply <NUM> sends a short circuit signal to the lathe <NUM>. After receiving the short circuit signal, the servo motor <NUM> on the lathe <NUM> lowers a rotary speed of the rotatable shaft <NUM> of the apparatus <NUM> for electrical machining. Therefore, under an action of elastic force of a spring <NUM> of the apparatus <NUM> for electrical machining, the spring <NUM> pulls back the first electrode <NUM> and the second electrode <NUM>, so as to increase sizes of the gap <NUM> between the first electrode <NUM> and the workpiece <NUM> and the gap <NUM> between the second electrode <NUM> and the workpiece <NUM>, thereby eliminating the short circuit and enabling the apparatus <NUM> for electrical machining to return to a normal operating state.

In another specific embodiment of the system <NUM> for electrical machining according to the present invention, the power supply <NUM> of the system <NUM> for electrical machining may further detect whether an open circuit occurs between the first electrode <NUM> and the workpiece <NUM> and between the second electrode <NUM> and the workpiece <NUM>. When the power supply <NUM> detects that an open circuit occurs, the power supply <NUM> sends an open circuit signal to the lathe <NUM>. After receiving the open circuit signal, the servo motor <NUM> on the lathe <NUM> increases a rotary speed of the rotatable shaft <NUM> of the apparatus <NUM> for electrical machining. Therefore, the first electrode <NUM> and the second electrode <NUM> further move far away from each other, elastic force of a spring <NUM> increases, and sizes of the gap <NUM> between the first electrode <NUM> and the workpiece <NUM> and the gap <NUM> between the second electrode <NUM> and the workpiece <NUM> are decreased, thereby eliminating the open circuit and enabling the apparatus <NUM> for electrical machining to return to a normal operating state.

Similarly, the system <NUM> for electrical machining according to the present invention may also be configured to machine the workpiece <NUM>' shown in <FIG>.

<FIG> are schematic diagrams of an apparatus <NUM>' for electrical machining according to a second specific embodiment of the present invention. <FIG> are schematic diagrams of the apparatus <NUM>' for electrical machining before a workpiece <NUM> is machined. <FIG> are schematic diagrams of the apparatus <NUM>' for electrical machining during a procedure of machining the workpiece <NUM>. As shown in <FIG>, similar to the apparatus <NUM> for electrical machining according to the first specific embodiment, the apparatus <NUM>' for electrical machining according to the second specific embodiment may also include a rotatable shaft <NUM> and an electrode <NUM> for electrical machining. The rotatable shaft <NUM> has a rotation axis <NUM>. The electrode <NUM> also includes a first electrode <NUM> and a second electrode <NUM>. The first electrode <NUM> and the second electrode <NUM> may be movably connected to the rotatable shaft <NUM>. In addition, the first electrode <NUM> and the second electrode <NUM> are symmetrically disposed relative to the rotation axis <NUM> of the rotatable shaft <NUM>. However, different from the apparatus <NUM> for electrical machining according to the first specific embodiment, in the apparatus <NUM>' for electrical machining according to the second specific embodiment, the first electrode <NUM> and the second electrode <NUM> further have rotation axes <NUM> and <NUM> of their own.

With reference to <FIG>, similar to the apparatus <NUM> for electrical machining according to the first specific embodiment, in the apparatus <NUM>' for electrical machining according to the second specific embodiment, when the rotatable shaft <NUM> is rotated, the first electrode <NUM> and the second electrode <NUM> can rotate together with the rotatable shaft <NUM> around the rotation axis <NUM> of the rotatable shaft <NUM>. Moreover, the rotatable shaft <NUM> may be rotated to generate centrifugal force. However, different from the apparatus <NUM> for electrical machining according to the first specific embodiment, in the apparatus <NUM>' for electrical machining according to the second specific embodiment, the first electrode <NUM> and the second electrode <NUM> can further rotate towards opposite directions around their own rotation axes <NUM> and <NUM> under an action of the centrifugal force. Therefore, the first electrode <NUM> and the second electrode <NUM> move relative to the rotatable shaft <NUM>. In addition, a rotational angle of the first electrode <NUM> and the second electrode <NUM> can also be controlled based on a rotary speed of the rotatable shaft <NUM>, thereby further controlling a moving distance of the first electrode <NUM> and the second electrode <NUM> relative to the rotatable axis <NUM>.

In the apparatus <NUM>' for electrical machining according to the second specific embodiment, the rotatable shaft <NUM> may also be provided with a limiting portion (not marked) for limiting a maximum moving distance of the first electrode <NUM> and the second electrode <NUM>.

With reference to <FIG>, when the apparatus <NUM>' for electrical machining needs to machine the workpiece <NUM>, the rotatable shaft <NUM> of the apparatus <NUM>' for electrical machining may be inserted into a hole <NUM> of the workpiece <NUM>, and certain gaps <NUM> and <NUM> are kept between the workpiece <NUM> and the first electrode <NUM> and the second electrode <NUM> respectively. Before the apparatus <NUM>' for electrical machining machines the workpiece <NUM>, the first electrode <NUM> and the second electrode <NUM> remain in an accommodation space <NUM> of the rotatable shaft <NUM> under an action of elastic force of a spring <NUM>. Moreover, in combination with <FIG>, before the workpiece <NUM> is machined, the hole <NUM> of the workpiece <NUM> has a first diameter D1.

With reference to <FIG>, when the apparatus <NUM>' for electrical machining machines the workpiece <NUM>, the first electrode <NUM>, the second electrode <NUM>, and the workpiece <NUM> are powered on, so that opposite electric polarities are carried between the first electrode <NUM> and the workpiece <NUM> and between the second electrode <NUM> and the workpiece <NUM>. Moreover, the rotatable shaft <NUM> is rotated in the hole <NUM> of the workpiece <NUM>. Rotation of the rotatable shaft <NUM> drives the first electrode <NUM> and the second electrode <NUM> to rotate together. The rotatable shaft <NUM> is rotated to generate the centrifugal force. The first electrode <NUM> and the second electrode <NUM> can rotate towards opposite directions around their own rotation axes <NUM> and <NUM> under the action of the centrifugal force. Therefore, the first electrode <NUM> and the electrode <NUM> move towards the workpiece <NUM> relative to the rotatable shaft <NUM>, and the spring <NUM> is extended. As the first electrode <NUM> and the second electrode <NUM> rotate, electrical discharges are generated between the first electrode <NUM> and the workpiece <NUM> that have opposite electric polarities and between the second electrode <NUM> and the workpiece <NUM> that have opposite electric polarities, so as to remove a portion of a material of the hole <NUM> of the workpiece <NUM>. Therefore, in combination with <FIG>, after the workpiece <NUM> is machined, the hole <NUM> of the workpiece <NUM> may have a second diameter D2. The second diameter D2 is greater than the first diameter D1. The rotational angle of the first electrode <NUM> and the second electrode <NUM> may be controlled based on the rotary speed of the rotatable shaft <NUM>, thereby further controlling the moving distance of the first electrode <NUM> and the second electrode <NUM> relative to the rotatable shaft <NUM>, so as to control a size of the gap <NUM> between the first electrode <NUM> and the workpiece <NUM> and a size of the gap <NUM> between the second electrode <NUM> and the workpiece <NUM>. Moreover, a value of the second diameter D2 of the hole <NUM> of the workpiece <NUM> after machining may be controlled.

Except that the first electrode <NUM> and the second electrode <NUM> of the apparatus <NUM>' for electrical machining according to the second specific embodiment are slightly different from those of the apparatus <NUM> for electrical machining according to the first specific embodiment, the apparatus <NUM>' for electrical machining according to the second specific embodiment has a structure generally similar to that of the apparatus <NUM> for electrical machining according to the first specific embodiment, and can obtain beneficial technical effects generally similar to those of the apparatus <NUM> for electrical machining according to the first specific embodiment. Therefore, details are not repeated herein.

Similarly, the apparatus <NUM>' for electrical machining according to the second specific embodiment may also be configured to machine the workpiece <NUM>' shown in <FIG>.

The system <NUM> for electrical machining shown in <FIG> may also use the apparatus <NUM>' for electrical machining according to the second specific embodiment. Details are not repeated herein.

The foregoing describes the specific embodiments of the apparatuses <NUM> and <NUM>' for electrical machining of the present invention by using an example in which the electrode <NUM> includes the two electrodes <NUM> and <NUM>. However, in the apparatuses <NUM> and <NUM>' for electrical machining of the present invention, the electrode <NUM> is not limited to including merely the two electrodes <NUM> and <NUM>.

In another specific embodiment of the apparatuses <NUM> and <NUM>' for electrical machining of the present invention, the electrode <NUM> may include a plurality of electrodes, the plurality of electrodes may be movably connected to the rotatable shaft <NUM>, and the plurality of electrodes are evenly distributed on the rotatable shaft <NUM>. When the rotatable shaft <NUM> is rotated, the plurality of electrodes can rotate together with the rotatable shaft <NUM>, and can move towards different directions relative to the rotatable shaft <NUM> under the action of the centrifugal force. Moreover, a moving distance of the plurality of electrodes relative to the rotatable shaft <NUM> can be controlled based on the rotary speed of the rotatable shaft <NUM>. An apparatus for electrical machining that uses a plurality of electrodes can obtain beneficial technical effects generally similar to those of apparatuses <NUM> and <NUM>' for electrical machining that use two electrodes <NUM> and <NUM>, for example, the apparatus <NUM> for electrical machining according to the first specific embodiment and the apparatus <NUM>' for electrical machining according to the second specific embodiment. The apparatus for electrical machining that uses the plurality of electrodes also has advantages such as a simple structure, a low cost, and ease to implement. In addition, during the machining procedure, the plurality of electrodes can simultaneously move towards the workpiece <NUM> or <NUM>' in different directions. Therefore, electrical discharges can be generated in a gap between the plurality of electrodes and the workpiece <NUM> or <NUM>', and the plurality of electrodes can simultaneously perform machining on the workpiece <NUM> or <NUM>'. Because the plurality of electrodes are evenly distributed on the rotatable shaft <NUM>, force exerted on the apparatus for electrical machining that uses the plurality of electrodes is even during the entire machining procedure. Therefore, the apparatus for electrical machining that uses the plurality of electrodes can ensure that a surface, obtained after the machining, of the workpiece <NUM> or <NUM>' has a good flatness.

For the regularly structured workpiece <NUM> (with reference to <FIG>) and the irregularly structured workpiece <NUM>' (with reference to <FIG>), the apparatus for electrical machining that uses at least more than two electrodes according to the present invention can remain receiving even force during the machining procedure. Therefore, the workpiece <NUM> or <NUM>' can obtain a good flatness after the machining.

In a comparative example not according to the claimed invention the electrode <NUM> may be a single electrode. Similarly, the single electrode may be movably connected to the rotatable shaft <NUM>. When the rotatable shaft <NUM> is rotated, the single electrode can rotate together with the rotatable shaft <NUM>, and can move relative to the rotatable shaft <NUM> under the action of the centrifugal force. Moreover, a moving distance of the single electrode relative to the rotatable shaft <NUM> can be controlled based on the rotary speed of the rotatable shaft <NUM>.

It should be understood that other corresponding structural characteristics of the apparatus for electrical machining may be modified correspondingly. Such simple modifications or equivalent replacements do not depart from the innovation essence of the apparatus for electrical machining according to the present invention, and still fall within the protection scope of the apparatus for electrical machining according to the claims.

The apparatus for electrical machining according to the specific embodiments of the present invention has advantages such as a simple structure, a low cost, and ease to implement, and is easy to carry.

<FIG> is a flowchart of a method for electrical machining according to a specific embodiment of the present invention. As shown in <FIG> and in combination with <FIG> and <FIG>, a method for electrical machining according to a specific embodiment of the present invention may include the following steps:.

In a step S1, movably connect an electrode <NUM> to a rotatable shaft <NUM>. The electrode <NUM> may be a single electrode, two electrodes, or a plurality of electrodes. For example, in a case in which the electrode <NUM> includes two electrodes, such as a first electrode <NUM> and a second electrode <NUM>, the first electrode <NUM> and the second electrode <NUM> are movably connected to the rotatable shaft <NUM>. Moreover, preferentially, the two electrodes <NUM> and <NUM> are symmetrically distributed relative to a rotation axis <NUM> of the rotatable shaft <NUM>. In a case in which the electrode includes a plurality of electrodes, the plurality of electrodes are movably connected to the rotatable shaft <NUM>. Moreover, preferentially, the plurality of electrodes are evenly distributed on the rotatable shaft <NUM>. In a specific embodiment, the step S1 further includes connecting an elastic element, for example, a spring <NUM>, to the electrode <NUM>, so as to position the electrode <NUM> relative to the rotatable shaft <NUM>. For example, in the case in which the electrode <NUM> includes the two electrodes of the first electrode <NUM> and the second electrode <NUM>, one spring <NUM> or two independent springs may be configured to position the first electrode <NUM> and the second electrode <NUM> relative to the rotatable shaft <NUM>.

In a step S2, insert the rotatable shaft <NUM> into a hole <NUM> of a workpiece <NUM>, and keep a certain gap between the electrode <NUM> and the workpiece <NUM>. When the electrode <NUM> includes more than two electrodes, keep a certain gap between each electrode and the workpiece <NUM>. As an example, the hole <NUM> of the workpiece <NUM> is a rotation hole, and the hole <NUM> of the workpiece <NUM> has a first diameter D1 (as shown in <FIG>) before machining.

In a step S3, power on the electrode <NUM> and the workpiece <NUM>, so that the electrode <NUM> and the workpiece <NUM> carry opposite electric polarities.

In a step S4, rotate the rotatable shaft <NUM> in the hole <NUM> of the workpiece <NUM>, so as to generate centrifugal force.

In a step S5, push the electrode <NUM> relative to the rotatable shaft <NUM> towards the workpiece <NUM> under an action of the centrifugal force, so as to remove a portion of a material of the hole <NUM> of the workpiece <NUM>. Therefore, further form a ring groove <NUM> in the hole <NUM> of the workpiece <NUM>, so that the hole <NUM> of the workpiece <NUM> has a second diameter D2 (as shown in <FIG>) after the machining, where the second diameter D2 is greater than the first diameter D1. When the electrode <NUM> includes two electrodes, for example, the first electrode <NUM> and the second electrode <NUM>, push the first electrode <NUM> and the second electrode <NUM> towards opposite directions under the action of the centrifugal force. When the electrode includes a plurality of electrodes, push the plurality of electrodes relative to the rotatable shaft <NUM> towards different directions of a hole wall of the workpiece <NUM> under the action of the centrifugal force.

A value of the generated centrifugal force may be controlled based on a rotary speed of the rotatable shaft <NUM>, thereby further controlling a moving distance of the electrode <NUM>, so as to control a size of a gap between the electrode <NUM> and the workpiece <NUM> and control a value of the second diameter D2. To ensure that the electrode <NUM> does not move excessively, movement of the electrode <NUM> may be limited when the electrode <NUM> moves to a maximum moving distance.

Rotation of the rotatable shaft <NUM> is properly controlled, so that the portion (that is, the ring groove <NUM>) that is obtained after material removing and that is of the hole <NUM> of the workpiece <NUM> has a complete cylindrical surface or a part of a cylindrical surface.

In a specific embodiment, the method for electrical machining may further include: supplying a pressured working fluid to the gap between the electrode <NUM> and the workpiece <NUM>. For example, in the case in which the electrode <NUM> includes the two electrodes of the first electrode <NUM> and the second electrode <NUM>, the pressured working fluid maybe supplied to a gap <NUM> between the first electrode <NUM> and the workpiece <NUM> and a gap <NUM> between the second electrode <NUM> and the workpiece <NUM>. Therefore, during a procedure of machining the workpiece <NUM>, scraps generated during the machining procedure can be drained in time, thereby ensuring cleanness of a machining area of the workpiece <NUM>.

In an optional specific embodiment of the method for electrical machining according to the present invention, it may be further detected whether a short circuit occurs between the electrode <NUM> and the workpiece <NUM>. When it is detected that a short circuit occurs, the rotary speed of the rotatable shaft <NUM> may be lowered. Therefore, under an action of elastic force of a spring <NUM>, the spring <NUM> pulls back the electrode <NUM>, so as to increase a size of the gap between the electrode <NUM> and the workpiece <NUM>, thereby eliminating the short circuit and returning to a normal operating state.

In another optional specific embodiment of the method for electrical machining according to the present invention, it may be further detected whether an open circuit occurs between the electrode <NUM> and the workpiece <NUM>. When it is detected that an open circuit occurs, the rotary speed of the rotatable shaft <NUM> may be increased. Therefore, the electrode <NUM> may further move relative to the rotatable shaft <NUM>, elastic force of a spring <NUM> increases, and a size of the gap between the electrode <NUM> and the workpiece <NUM> is decreased, thereby eliminating the open circuit and returning to a normal operating state.

In still another specific embodiment of the method for electrical machining according to the present invention, the rotatable shaft <NUM> may further move along the rotation axis <NUM> of the rotatable shaft <NUM>. Axial movement of the rotatable shaft <NUM> may be controlled to control axial movement of the electrode <NUM>. For example, axial movement of the rotatable shaft <NUM> may be continuously controlled, so as to control an axial depth of the ring groove <NUM> obtained by machining. Further, axial movement of the rotatable shaft <NUM> may be intermittently controlled, so as to obtain, by machining, a plurality of ring grooves <NUM> that are distributed at an interval.

Similarly, the method for electrical machining according to the present invention may not only be configured to machine the workpiece <NUM> shown in <FIG>, but may also be configured to machine the workpiece <NUM>' shown in <FIG>.

The method for electrical machining according to the specific embodiments of the present invention has advantages such as a simple structure, a low cost, and ease to implement.

Claim 1:
An apparatus (<NUM>) for electrical machining, comprising:
a rotatable shaft (<NUM>); and
an electrode for electrical machining, wherein the electrode may be movably connected to the rotatable shaft (<NUM>), wherein
when the rotatable shaft (<NUM>) is rotated, the electrode rotates together with the rotatable shaft (<NUM>) and moves relative to the rotatable shaft (<NUM>) under an action of centrifugal force, and a moving distance of the electrode is controlled based on a rotary speed of the rotatable shaft (<NUM>) wherein
the electrode comprises a first electrode (<NUM>) and a second electrode (<NUM>); characterized in that the rotatable shaft (<NUM>) is provided with a first passage (<NUM>) for transmitting a working fluid and the first electrode (<NUM>) is provided with a second passage (<NUM>) for transmitting the working fluid and the second electrode (<NUM>) is provided with a third passage (<NUM>) for transmitting the working fluid, wherein the first passage (<NUM>), the second passage (<NUM>) and the third passage (<NUM>) are interconnected.