A short-circuit protection structure for the cathode body of a small-diameter barrel produced by electrolytic machining.

Abstract

This invention designs a short-circuit prevention structure for the cathode body in electrolytic machining of small-diameter tube bores. By adding a composite structure of an "annular drainage groove + gradually widening directional drainage groove" to the traditional rear guide zone, it solves the problems of uneven flow field distribution and ablation short circuits caused by poor electrolyte drainage and accumulation at the tail end of the working tooth machining area during traditional cathode body electrolytic machining of tube bores. Specifically, the annular drainage groove is placed at the front end of the rear guide zone, utilizing the potential energy of the annular groove to rapidly guide the electrolyte retained at the end of the working tooth to the annular groove, achieving uniform circumferential distribution of the electrolyte introduced by the rear guide zone and reducing excessive accumulation of electrolyte waste at the end of the working tooth. The gradually widening directional drainage groove starts from the end of the working tooth and gradually widens along the spiral angle of the working tooth, effectively providing electrolyte drainage and ensuring that the electrolyte flow from the end of the working tooth to the drainage groove always proceeds stably forward along the spiral structure. The combination of these two structures effectively solves the short-circuit problem at the end of the traditional cathode body.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic machining technology, specifically relating to a short-circuit protection structure for the cathode body in electrolytic machining of small-diameter tube bores. Background Technology

[0002] Small-caliber barrels are widely used in rapid-fire equipment such as naval guns and aircraft cannons. The rifling accuracy and surface quality of their bores directly determine the weapon's ballistic stability and firing accuracy. Electrolytic machining, due to its advantages such as high processing efficiency, no mechanical cutting stress, high processing accuracy, and adaptability to complex rifling contours, is widely used in the machining of small-caliber barrel bores. However, with the increasing prevalence and adoption of small-caliber, high length-to-diameter ratio barrel bores, the use of traditional cathode bodies for machining these products has led to quality instability. This is mainly manifested in the lack of electrolyte drainage design at the tail end of the working teeth of traditional cathode bodies. This causes excessive electrolyte accumulation at the end of the machining area due to spiral motion, resulting in uneven radial electrolyte distribution and machining short-circuit erosion problems at the tail end of the working teeth. To solve this problem and achieve stable process quality, it is necessary to optimize the design of the rear guiding part of the traditional cathode body structure. Summary of the Invention

[0003] This invention addresses the problems of uneven flow field distribution and ablation short circuit caused by poor electrolyte drainage and accumulation at the tail end of the working tooth machining area during traditional cathode electrolytic machining of the tube bore. It constructs a composite structure of "annular drainage groove + gradually widening directional drainage groove", which significantly improves machining stability and fundamentally and effectively prevents short circuit at the end of the cathode working tooth.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a cathode body anti-short circuit structure for electrolytic machining of small-diameter tube bores, including cathode working teeth, rear guide, rear guide drainage groove and gradually widening guide groove.

[0005] The rear guide channel is located at the front of the rear guide and is a circumferentially symmetrical U-shaped diversion and pressure relief channel. One end of it is connected to the front guide channel of the rear guide and the other end is connected to the rear guide channel of the rear guide. Electrolyte diversion is achieved through a ring structure.

[0006] The gradually widening guide groove is designed as a gradually widening spiral structure. Starting from the end of the working tooth in the processing area, the groove extension trajectory strictly follows the spiral angle of the cathode working tooth, achieving conformal adaptation with the working tooth. The guide groove extends backward along the direction away from the processing area, and the groove width gradually increases linearly. After crossing the annular groove, it still unfolds according to the original spiral and gradually widening angle. The gradually widening structure can effectively provide electrolyte flow guarantee, ensuring that the electrolyte flow from the end of the working tooth to the guide groove always moves forward steadily along the spiral structure.

[0007] Compared with the prior art, the advantages and effects of the present invention are as follows: 1. Through the composite design of "annular drainage channel + gradually widening directional drainage channel", the annular drainage channel uses the potential energy of height difference to first guide the electrolyte that has stagnated and accumulated at the end of the working tooth. Then, in conjunction with the gradually widening drainage channel which is consistent with the structure of the working tooth processing area, the drained electrolyte can be discharged quickly and smoothly, thereby solving the short circuit erosion problem caused by uneven radial distribution of electrolyte at the tail end of the working tooth. Attached Figure Description

[0008] Figure 1 This is a half-sectional view of the novel cathode structure of the present invention; Figure 2 This is a half-sectional view of the conventional cathode body structure described in this invention; Figure 3 This is a streamline distribution diagram of a traditional cathode; Figure 4 This is a streamline distribution diagram of the novel cathode of the present invention; Figure 5 The flow velocity distribution cloud diagrams at the end cross section of the working tooth are shown for a conventional cathode and the novel cathode of this invention. Figure 6 The flow velocity distribution cloud diagrams are shown for the cross-section of the conventional cathode post-guide front end and the annular drainage groove of the novel cathode post-guide front end of this invention. Figure 7 The flow velocity distribution cloud diagrams at the rear guide end of the conventional cathode and the novel cathode of this invention are shown. Figure 8 This is a diagram showing the current density distribution on the corresponding machining surface at the tail end of traditional cathode electrolytic machining. Figure 9 This is a current density distribution diagram of the corresponding machining surface at the tail end of the novel cathode electrolytic machining process of the present invention; Reference numerals: 1-Cathode working tooth, 2-Rear guide, 3-Rear guide channel, 4-Gradually widening guide channel. Detailed Implementation

[0009] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments of this patent obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0010] This embodiment provides a short-circuit protection structure for the cathode body in a small-diameter tube internally processed by electrolysis, such as... Figure 1 As shown, it includes a cathode working tooth 1, a rear guide 2, a rear guide channel 3, and a guide channel 4.

[0011] 1) The rear guide 2 is the tail structure of the cathode body, with a length of 24.5mm. An annular drainage groove 3 is opened at the front middle section of the rear guide 5mm from the end of the processing gap. The annular groove is a circumferentially symmetrical U-shaped diversion and pressure relief groove with a width of 3mm and a depth of 2mm. The groove wall adopts a rounded transition treatment to reduce the liquid flow resistance. The drainage groove 3 is connected to the electrolyte through 16 evenly distributed gradually widening guide groove channels at the front of the rear guide, which can meet the drainage needs of each working tooth of the electrolyte.

[0012] 2) The guide channel 4 is a gradually widening spiral structure, with 16 channels corresponding to the cathode working teeth 1. Each guide channel starts from the end of the machining gap 2 at the end of the corresponding working tooth, and the channel extension trajectory strictly follows the spiral angle of the working tooth to achieve conformal adaptation. The width of the guide channel inlet end is 2.94 mm, and it extends backward along the direction away from the machining gap 3. After crossing the guide annular groove 3, it unfolds at the original angle, and the width of the end end is 4.28 mm, which can effectively realize the rapid guidance of electrolyte in the annular groove.

[0013] Furthermore, through finite element numerical simulation verification of the cathode of this invention and a conventional cathode, streamline distribution diagrams of the two cathodes were obtained (see...). Figure 3 and Figure 4 This further verifies the reliability of the novel cathode proposed in this invention. Comparing the streamline distributions in the two figures reveals that the flow velocity color gradients in the working tooth region are similar, indicating that the flow velocity in this region has not changed significantly. However, the new cathode of this invention, due to the radial annular guide groove, guides the streamlines to be more concentrated and regular, ensuring both uniform flow velocity and regular streamline distribution in the working tooth region. This enhances the directional flushing ability of the electrolyte to promptly remove products and bubbles, ensures that the working area is always fully filled with electrolyte to eliminate liquid-free areas, and weakens local low-pressure areas to prevent bubble accumulation. In contrast, the initial cathode streamline distribution diagram shows problems of scattered, disordered, and prominent crossover phenomena. Not only is there a significant stagnant zone and uneven flow velocity distribution upstream of the working tooth region, but there is also a significant electrolyte backflow problem. Some streamlines are also prone to deviating from the working area. These defects directly induce short-circuit risks in electrolytic processing.

[0014] Furthermore, by comparing and analyzing the velocity distribution cloud maps of the cathode of this invention and the conventional cathode at the end of the working tooth cross section (see...), Figure 5 ), and the velocity distribution cloud map of the annular drainage channel at the rear guide (see Figure 6 ) and subsequent guided end velocity distribution cloud map (see Figure 7As can be seen, the cathode of the present invention and the conventional cathode have a large number of "cavities" at the end of the working teeth and the front end of the rear guide, and the flow velocity is uneven. However, the flow velocity at both cross sections of the new cathode of the present invention is more uniform than that of the former, and the "cavitation" phenomenon is basically eliminated. This flow field optimization significantly improves the uniformity of the cathode flow field, the rationality of the flow velocity, and the disturbance effect without changing the structure of the working area. The risk of short-circuit ablation of the cathode body is also greatly reduced, and the processing stability is ultimately improved.

[0015] Furthermore, a coupled electric-current-temperature field simulation model for electrolytic machining of a gradually changing inner bore was constructed and verified, combined with the current density distribution diagram output by the model ( Figure 8 , Figure 9 Analysis shows that the peak current density at the tail of the traditional cathode is relatively high, and local overcurrent concentration is prone to occur. The difference between the average current and the median current on the left is 5.93A, the difference on the right is 11.04A, and the difference between the average current and the median current on both sides is 5.11A. The peak current density at the tail of the new cathode of this invention is significantly reduced, and the risk of local overcurrent is lower. The difference between the average current and the median current on the left is 5.91A; the difference on the right is 9.64A, a reduction of 12.7%; and the difference between the average current and the median current on both sides is 3.73A, a reduction of 27.0%. Compared with the traditional cathode, the cathode of this invention has a smaller average current offset, better current distribution balance on both sides, and a more uniform and stable overall current distribution. Actual processing verification shows that the average cathode lifespan is increased by more than 3 times.

Claims

1. A small-bore barrel bore electrolytic processing cathode body short-circuit prevention structure, comprising a cathode working tooth (1), a rear guide (2), a rear guide annular flow guide groove (3), and a gradually widened directional flow guide groove (4). Characterized in that: The rear guide (2) is an integral extension structure at the tail of the cathode body. A flow channel (3) is provided at the front end of the channel. The flow channel (3) is an annular flow channel for electrolyte. The channel body is arranged symmetrically in the circumference and has a U-shaped cross-section adapted to fluid flow. One end of the flow channel (3) is aligned and connected to the end of the cathode working tooth. It is used to receive and distribute the electrolyte evenly in the circumference, avoiding electrolyte disturbance caused by local velocity concentration due to traditional axial flow channels.

2. The cathode body short-circuit protection structure for electrolytic machining of a small-diameter tube bore according to claim 1, characterized in that: The guide groove (4) is a gradually widening spiral structure. Starting from the end of the working tooth (1), the guide groove trajectory extends strictly according to the spiral angle of the cathode working tooth (1). The guide groove (4) extends backward into the guide (2) area away from the working tooth, and the groove width gradually increases linearly. After crossing the guide groove (3), it continues to expand according to the original spiral and gradually widening angle. The gradually widening structure can effectively provide electrolyte flow guarantee, ensuring that the electrolyte flow from the end of the working tooth to the guide groove always moves forward steadily along the spiral structure. Through the cooperation of the above two structures, the short circuit problem caused by electrolyte stagnation and accumulation at the end of the traditional cathode body can be effectively solved.

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