Machine tool clamp for machining and repairing wall thickness difference of forced bomb body

Abstract

The utility model is suitable for the technical field of forced ammunition body repair, and provides a machine tool clamp for machining and repairing the wall thickness difference of a forced ammunition body, which comprises a body, the tensioning block is in intermittent fit with a kidney-shaped hole formed in the body and is used for tensioning the opening part of the inner hole of the elastic body; the pull rod is connected with a machine tool, the pull rod is in clearance fit with the inner hole of the body, an inclined plane is arranged on the pull rod and matched with the tensioning block, and when the machine tool drives the pull rod to move, the tensioning block is pushed through the inclined plane to move on the kidney-shaped hole of the body in the radial direction and used for tensioning the elastic body; the guide key is matched with a key groove formed in the pull rod and used for limiting the pull rod to move in the inner hole of the body in the axial direction. The multi-point clamping mode is utilized, clamping points are distributed at different positions of the blank, it is guaranteed that clamping force is evenly distributed, deformation caused by too large single-point stress is reduced, and therefore the stability and precision of the blank in the machining process are guaranteed.

Description

Technical Field

[0001] This utility model belongs to the field of mortar body repair technology, and in particular relates to a machine tool fixture for processing and repairing wall thickness differences in mortar bodies. Background Technology

[0002] Mortar bodies are generally initially formed through a casting process. These cast blanks are typically made of specific alloy materials to meet the strength and pressure resistance requirements of mortars during launch. However, common defects may occur during casting, such as subcutaneous porosity, sand holes, slag inclusions, and inconsistent wall thickness. These defects directly affect the quality and performance of the mortar, so appropriate measures must be taken for repair or improvement. Large variations in wall thickness in mortar body casting blanks are a relatively common casting defect, leading to several problems: uneven distribution of strength and stiffness; thinner sections are prone to stress concentration points, making them more susceptible to cracking or deformation under impact or high pressure, thus affecting the safety and reliability of the mortar; difficulty in weight control; precise weight control is crucial for military equipment, and large variations in wall thickness make it difficult to accurately predict and control the total weight of the finished product, potentially affecting its flight characteristics and range; and difficulty in controlling the center of gravity shift; uneven wall thickness causes the mortar's center of gravity to shift, directly affecting its performance. Its flight stability and ballistic characteristics deviate from the predetermined trajectory during flight, reducing accuracy; assembly issues arise, as uneven wall thickness can lead to poor fit during assembly, affecting the overall assembly quality and performance of the weapon system; safety risks exist, as thinner areas may not withstand the high internal pressure at the moment of explosion, leading to premature rupture or detonation, increasing operator safety risks, and making it more susceptible to damage during transportation and storage, reducing its shelf life and operational safety; economic impacts are also significant, as any wall thickness variation exceeding the allowable range is considered a defective product, increasing scrap rates and production costs to ensure performance and safety. In conclusion, wall thickness variation in mortar projectiles not only affects their performance and safety but also increases manufacturing and usage costs. Therefore, controlling and reducing mortar wall thickness variation is one of the key factors in improving mortar performance and reliability.

[0003] The mortar's internal cavity is formed through a casting process, and its surface quality and dimensional accuracy already meet the requirements for use, so no fine machining is needed. Its internal cavity is mainly used to house components such as explosives and fuses, and the installation and function of these components do not depend on the extremely high precision of the internal cavity. The mortar's external shape needs to be machined according to requirements to ensure its dimensional accuracy and geometric tolerances, which is the control of wall thickness difference accuracy. The internal cavity is not machined and the wall thickness difference of the projectile needs to be guaranteed. Therefore, the internal cavity surface of the projectile has very stable interchangeability with the universal standard surface. Using the unmachined internal cavity surface as the positioning reference for machining the external shape can effectively solve the problem of projectile wall thickness difference.

[0004] To address this issue, it is necessary to resolve the problem of uneven wall thickness in the casting of the blank bullet. This can be achieved through machining to ensure consistent wall thickness and enable high-efficiency, high-quality batch processing. The machining equipment involved is a CNC lathe. On the lathe, the workpiece is fixed in place by a fixture, ensuring it occupies the correct machining position and is reliably clamped. The lathe and cutting tools are then used to bring the workpiece to the required technical specifications.

[0005] The shape of a mortar projectile is usually not a perfect cylinder or sphere, but rather has various protrusions, depressions, and other complex features. These irregular shapes make it difficult for traditional clamps to effectively fix and position it. Existing clamps are custom-made, extended, special three-jaw external clamps that repeatedly calibrate the internal cavity to ensure accuracy before processing. When manually clamping, the operator's skill and experience greatly affect the clamping effect, making it impossible to guarantee quality. Frequent clamping adjustments and calibrations increase equipment downtime, reduce equipment utilization, increase the labor intensity of operators, and seriously affect the overall processing efficiency of the production line. Utility Model Content

[0006] The purpose of this utility model embodiment is to provide a machine tool fixture for processing and repairing the thickness difference of the mortar projectile body wall, aiming to solve the problems mentioned in the background art.

[0007] This utility model embodiment is implemented as follows: a machine tool fixture for processing and repairing thickness differences in the wall of a mortar projectile, comprising:

[0008] The body, one end of which engages with the inner cavity of the projectile;

[0009] The tensioning block, which intermittently engages with the waist-shaped hole on the body, is used to tension the inner opening of the elastic body;

[0010] A pull rod is connected to a machine tool and has a clearance fit with the inner hole of the body. The pull rod has an inclined surface that cooperates with a tensioning block. When the machine tool drives the pull rod to move, the inclined surface pushes the tensioning block to move radially on the waist-shaped hole of the body to tension the elastic body.

[0011] The guide key, which cooperates with the keyway on the tie rod, is used to restrict the axial movement of the tie rod within the inner hole of the body.

[0012] Preferably, the conical surface of the end of the body that mates with the inner cavity of the projectile matches the conical surface at the depth of the inner cavity of the projectile.

[0013] Preferably, the end of the pull rod that mates with the inner hole of the main body is provided with a limiting cylinder to prevent the tensioning block from being completely pushed out or falling into the main body.

[0014] Preferably, the machine tool fixture further includes a movable center, the mounting end of which is connected to the machine tool tailstock, and the working end of which engages with the center hole at the tail end of the projectile for support.

[0015] This utility model provides a machine tool fixture for machining and repairing mortar body wall thickness differences. It ensures uniform clamping force distribution, uses the inner cavity opening and inner wall end face of the mortar body as reference surfaces for positioning, and ensures consistent clamping position each time. It also features a movable center point on the machine tool tailstock supporting the pre-machined center hole of the mortar body, which assists in positioning and reduces accumulated errors, thus withstanding the cutting forces during machining. The fixture exhibits good rigidity and stability in machining performance and accuracy. Utilizing a multi-point clamping method, with clamping points distributed across different parts of the blank, ensures uniform clamping force distribution, reduces deformation caused by excessive force at a single point, and thus ensures the stability and accuracy of the blank during machining. This effectively solves the problem of difficult clamping of mortar body blanks, improving machining quality and production efficiency. Attached Figure Description

[0016] Figure 1 An exploded view of a machine tool fixture for processing and repairing the thickness difference of a mortar projectile body, provided as an embodiment of this utility model;

[0017] Figure 2 A cross-sectional view of a machine tool fixture for processing and repairing the wall thickness difference of a mortar projectile, provided in an embodiment of this utility model;

[0018] Figure 3 A schematic diagram illustrating the state of a machine tool fixture not being clamped when processing and repairing the wall thickness difference of a mortar projectile, provided as an embodiment of this utility model;

[0019] Figure 4 A schematic diagram of the state of a machine tool fixture clamping a mortar body for processing and repairing wall thickness differences, provided for an embodiment of this utility model;

[0020] Figure 5 A schematic diagram of the tensioning block in a machine tool fixture for processing and repairing the wall thickness difference of a mortar projectile, provided as an embodiment of this utility model;

[0021] Figure 6 This is a schematic diagram of the structure of a guide key in a machine tool fixture for processing and repairing the thickness difference of a mortar projectile body, provided as an embodiment of the present invention.

[0022] In the attached diagram: 1-body; 2-pull rod; 3-tensioning block; 4-guide key; 5-projectile; 6-moving center; 7-machine tool tailstock. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0024] The specific implementation of this utility model will be described in detail below with reference to specific embodiments.

[0025] like Figures 1 to 6 The diagram shown illustrates the structure of a machine tool fixture for machining and repairing thickness differences in mortar projectile walls, according to an embodiment of this utility model. The fixture includes:

[0026] Body 1, one end of which engages with the inner cavity of the projectile 5;

[0027] The tensioning block 3 intermittently engages with the waist-shaped hole on the body 1 to tension the inner opening of the elastic body 5;

[0028] The pull rod 2 is connected to the machine tool and has a clearance fit with the inner hole of the body 1. The pull rod 2 is provided with an inclined surface that cooperates with the tensioning block 3. When the machine tool drives the pull rod 2 to move, the inclined surface pushes the tensioning block 3 to move radially on the waist-shaped hole of the body 1 to tension the elastic body 5.

[0029] The guide key 4, which cooperates with the keyway on the pull rod 2, is used to restrict the axial movement of the pull rod 2 within the inner hole of the body 1.

[0030] In one embodiment of this utility model, the machine tool fixture for processing and repairing the thickness difference of the mortar body wall addresses the problems raised in the prior art. It is provided with a body 1 and a tie rod 2 cooperating. The connection method between the body 1 and the CNC lathe spindle mainly depends on the machine tool chuck model, which is generally universal. The body 1 is processed according to the provided machine tool chuck model. Specifically, the body 1 is assembled with the connecting disc tapered hole guide and positioning hole on the machine tool spindle. The alignment and correction fixture is coaxial with the spindle, with a coaxiality of no more than 0.015mm, and is fixed with corresponding screws.

[0031] The inner hole of body 1 is clearance-fitted with pull rod 2, with a fit tolerance controlled within 0.02-0.04mm. The inner hole of body 1 has a guide groove, which is related to three evenly distributed oblong holes on the outer circumference of body 1. These oblong holes are clearance-fitted with tensioning block 3, and their surface roughness is controlled within Ra 0.8μm. They are used to tension the inner opening of projectile 5. The size of the cylinder at the right end of body 1 is determined based on the inner opening size of projectile 5, generally being 1-2mm smaller for ease of loading and unloading.

[0032] The pull rod 2 is screwed to the internal cylinder of the machine tool spindle. The extension and retraction of the spindle cylinder drives the axial movement of the pull rod 2. The keyway on the pull rod 2 is installed in conjunction with the guide key 4. The length of the pull rod 2 is calculated based on the connecting rod of the machine tool cylinder to ensure the extension and retraction of the cylinder. The guide key 4 moves at both ends inside the pull rod 2. The three evenly distributed inclined surfaces on the right end of the pull rod 2 are related to the keyway and are consistent with the guide groove in the inner hole of the body 1 and the three evenly distributed waist-shaped holes on the outer circle. This is to ensure that the three waist-shaped holes are consistent with the direction of the three evenly distributed inclined surfaces of the pull rod 2. Specifically, the three evenly distributed inclined surfaces of the pull rod 2 are at 30° with the axis. The inclined surfaces are smooth and the roughness is controlled at Ra0.8μm. The inclined surfaces slide relative to the tensioning block 3.

[0033] The tensioning block 3 is fitted with the oblong hole of the body 1 with a clearance fit, and the fit tolerance is controlled within 0.02-0.03mm. The inclined surface of the tensioning block 3 is at 60° with the axis of 1. The three tensioning blocks 3 are the same size and shape. The axial movement of the pull rod 2 is applied to the tensioning block 3 and converted into radial movement through the guide of the oblong hole of the body 1, thereby realizing the function of tensioning the projectile 5. The roughness of the tensioning block 3 is controlled within Ra0.8μm to ensure smooth movement. The tensioning surface of the tensioning block 3 is consistent with the arc of the inner hole of the projectile 5 to ensure a large contact surface and increase static friction. A 2.0mm boss is left at the root of the tensioning block 3 to prevent it from falling out of the oblong hole of the body 1. The front end of the tensioning block is guided to facilitate free retraction during clamping.

[0034] The lower half of the guide key 4 is tightly fitted and fixed to the keyway on the guide key 4. The upper half of the guide key 4 is loosely fitted to the guide groove in the inner hole of the body 1. The fit tolerance is controlled within 0.02-0.03mm to ensure that the pull rod 2 moves axially in the inner hole of the body 1 and prevents relative rotational movement between the body 1 and the pull rod 2.

[0035] The projectile 5 is a cast blank, which is a blank with a process center hole machined by positioning the inner cavity. When the projectile 5 is clamped, the inner cavity is directly inserted into the body 1 until the bottom conical surface is positioned. The tensioning action is started by switching on the CNC machine tool. The machine tool cylinder drives the pull rod 2 to act axially in the body 1 and simultaneously pushes the three pushing tensioning blocks 3 to move radially on the guide of the waist-shaped hole in the body 1, thereby realizing the function of tensioning the projectile 5.

[0036] like Figure 1 As shown, in a preferred embodiment of the present invention, the conical surface of one end of the body 1 that mates with the inner cavity of the projectile 5 matches the conical surface at the depth of the inner cavity of the projectile 5.

[0037] The conical surface at the rightmost end of the cylindrical surface of the main body 1 matches the conical surface at the depth of the inner cavity of the projectile 5. The conical surface can automatically align itself to ensure that the axis of the inner cavity of the projectile 5 is coaxial with that of the main body 1. At the same time, it positions and controls the depth of the inner cavity of the projectile 5 to ensure the precise positioning of the blank.

[0038] like Figures 1 to 4 As shown, in another preferred embodiment of the present invention, the end of the pull rod 2 that mates with the inner hole of the body 1 is provided with a limiting cylinder to prevent the tensioning block 3 from being completely pushed out or falling into the body 1.

[0039] A small cylinder is provided at the right end of the lever 2 as a limit to prevent the tensioning block 3 from being completely pushed out when the tensioning stroke is too large, or to be manually dropped into the body 1 when the tensioning block 3 is contracted.

[0040] like Figures 1 to 2 As shown, in a preferred embodiment of the present invention, the machine tool fixture further includes a movable center 6. The mounting end of the movable center 6 is connected to the machine tool tailstock 7, and the working end of the movable center 6 is engaged with the center hole at the tail end of the projectile 5 for support and assistance.

[0041] The projectile body 5 is a relatively long shaft part. In order to improve the support effect, the process center hole at its tail can be supported and positioned by the action of 6 and the machine tool tailstock 7 to reduce the cumulative error, so as to withstand the cutting force during the processing and improve the processing rigidity and processing accuracy of the workpiece.

[0042] The movable tip 6 is a general-purpose component, mainly used for precise positioning and support of the workpiece. It acts on the process center hole at the tail of the projectile 5. The tail of the movable tip 6 is mounted on the machine tool tailstock 7. The machine tool tailstock 7 is a component on the CNC machine tool. It can move along the guide rail on the machine bed to adapt to workpieces of different lengths. It is generally a hydraulic tailstock, which drives the extension and retraction of the tailstock cylinder through a hydraulic system.

[0043] The installation steps of this machine tool fixture are as follows: First, manually screw the pull rod 2 into the machine tool spindle internal cylinder to the appropriate position, install the guide key 4 on the pull rod 2, then install the body 1, install the three tensioning blocks 3 from inside the body 1 into the corresponding oblong holes, then align the guide groove of the body 1 with the guide key 4 and insert it into the pull rod 2, rotate to align the corresponding hole positions and pre-tighten with screws, use a dial indicator to calibrate it to be coaxial with the spindle, the coaxiality is not greater than 0.015mm, and then fix it with screws; install the movable center 6 into the machine tool tailstock 7, adjust the machine tool tailstock 7 to the appropriate position, ensure that when the tailstock cylinder extends, the movable center 6 completely presses against the projectile 5, and after the tailstock cylinder retracts, the projectile 5 can be freely removed from the body 1;

[0044] The working principle of this machine tool fixture is as follows: When the chuck is in the relaxed state (spindle cylinder retracted state), the inner cavity of the projectile 5 is directly inserted into the body 1 until the bottom conical surface is positioned. The conical surface ensures that the bottom of the projectile 5 is concentric with the body 1. When the opening of the projectile 5 contacts the tensioning block 3, it will freely retract into the body 1. The clamping action is started by the CNC machine tool switch. The machine tool spindle cylinder drives the pull rod 2 to act axially in the body 1, while simultaneously pushing the three tensioning blocks 3 to move radially along the guide of the oblong hole in the body 1. This achieves the function of tensioning the projectile 5 and ensures that the opening of the projectile 5 is concentric with the body 1. The concentricity of both ends of the inner cavity of the projectile 5 with the body 1 ensures that the inner cavity of the projectile is coaxial with the fixture. Finally, the machine tool tailstock cylinder switch is activated to allow the movable top... The tip 6 supports the process center hole at the tail of the projectile 5, which assists in positioning and further reduces cumulative errors, so as to withstand the cutting force during the machining process and improve the machining rigidity and machining accuracy of the workpiece. After clamping, the machine tool can cut. This fixture can complete the machining of the entire shape of the projectile 5, as well as control the depth and total length of the inner cavity. It can realize the concentrated machining of the process, reduce the number of clamping times and avoid cumulative errors. After machining, the hydraulic cylinder switch is activated, which drives the movable tip 6 to leave the projectile 5. Then the CNC machine tool release switch is activated, and the machine tool spindle hydraulic cylinder retracts, which drives the pull rod 2 to retract axially in the body 1. At this time, the three tensioning blocks 3 are not pushed in the waist-shaped hole of the body 1. The mouth of the projectile 5 easily touches it into the body 1, and the projectile 5 can be completely removed.

[0045] This fixture effectively solves the problem of difficult clamping of mortar blanks, ensures that the wall thickness difference of the mortar is within the allowable range, and controls the dimensional tolerances of the mortar cavity depth and total length to meet technical requirements. It significantly improves processing quality and production efficiency. Specifically, it allows multiple processes to be completed in one clamping, is convenient to clamp, has accurate positioning, good processing stability, improved processing efficiency, reduced labor intensity, increased equipment utilization, reduced production costs, improved product quality pass rate, and eliminated quality and safety risks.

[0046] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A machine tool fixture for machining and repairing thickness differences in the wall of a mortar projectile, characterized in that, include: Body (1), one end of which is fitted into the inner cavity of the projectile (5); The tensioning block (3) is intermittently fitted with the waist-shaped hole opened on the body (1) to tension the inner hole of the elastic body (5); A pull rod (2) is connected to a machine tool. The pull rod (2) is clearance-fitted with the inner hole of the body (1). The pull rod (2) is provided with an inclined surface that cooperates with the tensioning block (3). When the machine tool drives the pull rod (2) to move, the tensioning block (3) is pushed radially on the waist-shaped hole of the body (1) through the inclined surface to tension the elastic body (5). The guide key (4) cooperates with the keyway on the pull rod (2) to restrict the pull rod (2) from moving axially within the inner hole of the body (1).

2. The machine tool fixture for machining and repairing the thickness difference of a mortar projectile body according to claim 1, characterized in that, The conical surface of one end of the body (1) that mates with the inner cavity of the projectile (5) matches the conical surface at the depth of the inner cavity of the projectile (5).

3. The machine tool fixture for machining and repairing the thickness difference of a mortar projectile body according to claim 1, characterized in that, The end of the pull rod (2) that mates with the inner hole of the body (1) is provided with a limiting cylinder to prevent the tensioning block (3) from being completely pushed out or falling into the body (1).

4. The machine tool fixture for machining and repairing the thickness difference of a mortar projectile body according to claim 1, characterized in that, The machine tool fixture also includes a movable center (6), the mounting end of which is connected to the machine tool tailstock (7), and the working end of the movable center (6) is engaged with the center hole at the tail end of the projectile (5) for support and assistance.

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