A three-fold scale ruler dedicated to mechanical or engineering drawings

Abstract

The utility model discloses a three -fold scale special for mechanical or engineering drawing relates to drawing tool technical field. The scale includes the main ruler, left folding ruler, right folding ruler, limit axle and spring dowel. Right folding ruler rotatory connection in main ruler right -end, and left folding ruler is through limit axle and spring dowel and the slide connection of main ruler's guide through -hole. Limit axle and left folding ruler are fixedly connected through mortise and tenon structure and can rotate relative to spring dowel, and spring dowel is placed in limit axle and is limited rotation angle through limit groove. Through pressing the button of spring dowel, realizes sliding locking with the cooperation of friction surface and main ruler key groove. The utility model utilizes three -fold structure to have realized portable storage, through the unique limit axle and spring dowel subassembly, not only realized the automatic parallel position of left folding ruler, also realized the arbitrary stepless regulation and high accuracy locking of parallel line interval, and the efficiency and precision of mechanical drawing have been improved greatly.

Description

Technical Field

[0001] This utility model relates to the field of drawing tools, and in particular to a three-fold ruler specifically for mechanical or engineering drawing. Background Technology

[0002] In the daily work of mechanical design and engineering drawing, drawing high-precision parallel lines is a very frequent and fundamental operation. Traditionally, drafters often need to use a T-square and set squares, or two set squares alternately, to draw parallel lines. This method not only relies on close hand coordination and requires high operational stability, but is also prone to slight displacement due to hand tremors during frequent movements, leading to deviations in parallelism. Although some rulers with parallel drawing functions exist on the market, most of these tools have relatively simple structures, either being bulky and inconvenient to carry, or sacrificing structural rigidity and adjustment precision in their folding and portable design. In particular, existing folding drafting rulers often lack an internal mechanism that can simultaneously satisfy rapid unfolding and positioning, as well as stepless adjustment and stable locking of parallel line spacing. When drawing parallel lines with non-standard spacing or strict requirements for spacing accuracy, existing tools struggle to maintain portability while achieving smooth sliding and reliable positioning, resulting in low drawing efficiency and difficulty in guaranteeing accuracy.

[0003] Therefore, this utility model proposes a three-fold scale ruler specifically for mechanical or engineering drawing to overcome the shortcomings of the prior art. Utility Model Content

[0004] In view of the problems existing in the portable drawing rulers, such as unstable unfolding positioning structure, cumbersome parallel line spacing adjustment operation, unreliable locking mechanism leading to easy movement during drawing, and difficulty in achieving high-precision stepless adjustment, this utility model aims to provide a three-fold scale ruler with an improved structure that can effectively solve the above problems for mechanical or engineering drawing.

[0005] This utility model provides a three-fold scale ruler for mechanical or engineering drawing, comprising: a main scale, wherein a guide hole extending along the length direction is provided on the main scale, and a keyway is recessed on the inner side wall of the guide hole; a right folding scale, wherein the right folding scale is rotatably connected to the right end of the main scale by a fixing pin; and a left folding scale, a limiting shaft and a spring clip.

[0006] The left folding ruler is slidably connected to the guide hole of the main ruler through the limiting shaft and the spring clip. The limiting shaft is housed and fixed in a groove opened at the connecting end of the left folding ruler. A boss structure is provided on the bottom surface of the groove. A mortise is provided at the lower end of the limiting shaft to match the boss structure. The boss structure is embedded in the mortise to form a fixed fit, which is configured so that the left folding ruler can drive the limiting shaft to rotate synchronously with respect to the spring clip.

[0007] Furthermore, the spring catch is disposed inside the limiting shaft and extends into the guide through hole of the main scale. The spring catch is provided with an operation button, and the side wall of the operation button is connected to a locking friction surface. The operation button part of the spring catch is located in the keyway, and the top surface of the operation button is not higher than the upper surface of the main scale. By pressing the operation button, the contact state between the locking friction surface and the inner wall of the keyway of the main scale is changed, so as to realize the sliding adjustment or fixed locking of the left folding ruler on the main scale. The limiting shaft and the spring catch are slidably connected through the receiving cavity and arc-shaped limiting groove opened in the limiting shaft and the side limiting block provided on the spring catch to limit the rotation angle.

[0008] Preferably, the spring latch has an internal elastic reset member, one end of which abuts against the inner wall of the spring latch, and the other end abuts against the limiting shaft or the relevant fixing part of the main scale. The elastic reset member is configured to provide continuous elastic force, so that in its natural state without external pressure, the spring latch tends to reset in a specific direction, thereby maintaining the pressed or separated state of the locking friction surface and the keyway, and assisting in realizing the press-type locking and unlocking logic.

[0009] Preferably, the limiting shaft has a receiving cavity along its axial direction, and the side wall of the limiting shaft has an arc-shaped limiting groove communicating with the receiving cavity. Correspondingly, a side limiting block protrudes from the side of the spring latch, and the side limiting block slides within the arc-shaped limiting groove. During the rotation and unfolding of the left folding ruler, the side limiting block transitions from the left end face to the right end face within the arc-shaped limiting groove, and the physical contact of the end faces restricts the rotation angle of the left folding ruler, ensuring that it maintains a strict parallel relationship with the right folding ruler after unfolding.

[0010] Preferably, the connection between the right folding ruler and the main ruler is provided with a positioning end face. When the right folding ruler is rotated clockwise around the fixing pin to the unfolded position, the positioning end face of the right folding ruler is in close contact with the right side end face of the main ruler, thereby providing a stable right-side reference for the entire drawing process.

[0011] Preferably, the main scale surface is provided with high-precision graduation lines, and the lower edge of the left folding scale is provided with a reading ramp or reading reference surface. The reading ramp extends to a position adjacent to the high-precision graduation lines to eliminate parallax, allowing the user to accurately adjust the position of the left folding scale according to the graduation lines, thus meeting the requirements for drawing high-precision parallel lines.

[0012] Preferably, the guide hole of the main scale has a stepped structure, the keyway is located on the side wall of the guide hole, and the cross-sectional shape of the spring clip matches the cross-sectional shape of the guide hole. This fit not only provides guidance but also prevents the spring clip from rotating relative to the main scale, ensuring the stability of the locking mechanism.

[0013] Preferably, the left-folding ruler and the right-folding ruler are of equal length, and in the folded state, the left-folding ruler and the right-folding ruler can be stored in the storage slots opened on the bottom surface of the main ruler. This design allows the three-fold ruler to form a compact whole when not in use, greatly improving portability.

[0014] This utility model has the following beneficial effects: 1. In this utility model, by setting a sliding locking component consisting of a limiting shaft and a spring clip in the guide hole of the main scale, and by using the locking friction surface of the side wall of the spring clip in conjunction with the keyway of the main scale, the problem of the existing drawing tools being unable to achieve stepless adjustment of spacing and unstable position after adjustment when drawing parallel lines is solved. It achieves the technical effect of firmly locking the left folding ruler at any position of the main scale by simply pressing the operation button and using friction, thereby realizing high-precision parallel line drawing at any spacing and preventing displacement during the drawing process.

[0015] 2. In this utility model, by opening an arc-shaped limiting groove on the side wall of the limiting shaft and setting a side limiting block on the spring clip, the relative sliding and end face abutment of the two solves the problem that the unfolding angle of existing folding rulers is difficult to control precisely and often requires the use of a protractor or triangle to calibrate the parallel state. It achieves the technical effect that rotating the left folding ruler will automatically limit it to an unfolded state that is strictly parallel to the right folding ruler, greatly simplifying the preparation process before drawing and improving the drawing efficiency. Attached Figure Description

[0016] Figure 1 This is a three-dimensional schematic diagram of a three-fold scale ruler specifically for mechanical or engineering drawing proposed in this utility model; Figure 2 This is a schematic diagram of the spring latch structure of a three-fold ruler for mechanical or engineering drawing purposes proposed in this utility model. Figure 3This is a schematic diagram of the left-folding ruler of a three-fold ruler specifically for mechanical or engineering drawing, as proposed in this utility model.

[0017] Legend: 1. Main scale; 2. Left folding scale; 3. Right folding scale; 4. Spring clip; 5. Limiting shaft; 6. Fixing pin. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions in the embodiments of this utility model 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 this utility model, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0019] Example: Please refer to Figures 1 to 3 This utility model provides a three-fold ruler specifically for mechanical or engineering drawing, which aims to solve the structural defects of existing drawing tools in that the operation is cumbersome and the spacing is difficult to adjust quickly and accurately when drawing parallel lines.

[0020] like Figure 1 and Figure 2 As shown, the three-fold ruler mainly consists of a main scale 1, a left folding scale 2, a right folding scale 3, a spring clip 4, a limiting shaft 5, and a fixing pin 6. The main scale 1 serves as the supporting base of the overall structure. Its surface has a guide hole along the length direction. The guide hole penetrates the upper and lower surfaces of the main scale 1 and has a stepped structure, providing guiding space for the movement of subsequent components and cooperating to achieve a locking function. A keyway is recessed on the inner side wall of the guide hole. The keyway is located in the upper wide area of ​​the guide hole and is used to cooperate with the locking mechanism to fix the position. The upper surface of the main scale 1 is etched with high-precision scale lines along the length direction to provide a length measurement benchmark. The bottom surface of the main scale 1 has a storage slot for storing the left folding scale 2 and the right folding scale 3 when not in use, so as to reduce the overall volume and facilitate carrying.

[0021] The right folding ruler 3 is located at the right end of the main ruler 1 and is rotatably connected to the main ruler 1 by a fixing pin 6. The fixing pin 6 is a countersunk pin that passes through the right folding ruler 3 and is fixed to the main ruler 1. The end of the fixing pin 6 does not protrude from the surface of the right folding ruler 3 to ensure that the ruler surface is flat. The connection of the right folding ruler 3 is provided with a positioning end face. When the right folding ruler 3 rotates clockwise around the fixing pin 6 to the unfolded position, the positioning end face is tightly fitted with the right end face of the main ruler 1, thereby limiting the rotation angle of the right folding ruler 3 and keeping it in a specific perpendicular or set angle geometric relationship with the main ruler 1.

[0022] The left folding ruler 2 is slidably connected to the guide hole of the main ruler 1 through a composite assembly consisting of a limiting shaft 5 and a spring clip 4. The connecting end of the left folding ruler 2 is provided with a groove for accommodating the limiting shaft 5, and the bottom surface of the groove is provided with a boss structure. The lower end of the limiting shaft 5 is provided with a mortise that matches the boss structure. The boss structure is embedded in the mortise to form a stable fixed fit, so that when the left folding ruler 2 is rotated by an external force, it can drive the limiting shaft 5 to rotate synchronously with the spring clip 4. The lower edge of the left folding ruler 2 is provided with a reading slope. In the assembled state, the reading slope is close to the high-precision scale line of the main ruler 1 to eliminate parallax and improve reading accuracy.

[0023] To solve the problems of precise angle positioning of the left-folding ruler 2 during unfolding and sliding locking on the main ruler 1, the three-fold scale also includes a precise limiting and locking transmission structure, which is achieved by the limiting shaft 5 and the spring latch 4 through a specific internal fit.

[0024] Please refer to the following carefully. Figure 2 and Figure 3 The limiting shaft 5 has a receiving cavity extending along its axial direction. The receiving cavity is located at the center of the limiting shaft 5. An arc-shaped limiting groove communicating with the receiving cavity is also provided on the cylindrical side wall of the limiting shaft 5. The arc-shaped limiting groove extends circumferentially within a preset angle range. Its two ends form a left stop end face and a right stop end face for physical blocking, respectively, to limit the start and end points of the rotation stroke. The spring clip 4 is movably installed in the guide through hole of the main scale 1. Its main body extends downward and is inserted into the receiving cavity of the limiting shaft 5. A side limiting block is integrally formed on the side of the spring clip 4. The size of the side limiting block is adapted to the groove width of the arc-shaped limiting groove.

[0025] In the assembled state, the side limiting block of the spring clip 4 slides into the arc-shaped limiting groove of the limiting shaft 5. This sliding groove structure ensures that the limiting shaft 5 can rotate relative to the spring clip 4 but is limited by the angle. Specifically, since the shape of the spring clip 4 is adapted to the cross-section of the guide hole of the main scale 1, the spring clip 4 cannot rotate relative to the main scale 1. When the left folding scale 2 drives the limiting shaft 5 to rotate clockwise, the arc-shaped limiting groove is displaced relative to the stationary side limiting block. When it rotates to the unfolded position, the side limiting block smoothly transitions from the left stop end face of the arc-shaped limiting groove and finally abuts against the right stop end face, using mechanical hard limiting to prevent the left folding scale 2 from continuing to rotate. At this time, the left folding scale 2 and the right folding scale 3 are in a strictly parallel state.

[0026] Meanwhile, an elastic reset element is provided inside the spring latch 4. The elastic reset element is located in the hollow cavity of the spring latch 4. One end of the elastic reset element abuts against the top of the inner wall of the spring latch 4, and the other end passes through the limiting shaft 5 and abuts against the left folding ruler 2 or related fixing part. The elastic reset element is always in a compressed state, providing the spring latch 4 with a continuous upward reset force, so that the upper structure of the spring latch 4 has a tendency to move into the keyway of the main ruler 1. For the specific form of the elastic reset element, those skilled in the art can use a variety of conventional elastic elements such as helical springs and spring sheets. The specific elastic coefficient is set according to the requirements of locking friction force.

[0027] Based on the above embodiments, the present invention may further include the following preferred technical solutions: As a preferred embodiment, in order to ensure the rotational synchronization and connection stability between the left folding ruler 2 and the limiting shaft 5, the boss structure protruding from the bottom surface of the groove inside the left folding ruler 2 and the mortise opened at the lower end of the limiting shaft 5 form a precise tenon and mortise fit structure. The boss structure is preferably frustum or polygonal prism, and the mortise is a groove of the corresponding shape, ensuring that the two will not slide relative to each other during the rotation of the left folding ruler 2 around the limiting shaft 5, thus achieving a rigid connection.

[0028] In a preferred embodiment, in order to provide precise angular positioning, the arc-shaped positioning groove on the side wall of the positioning shaft 5 has a precisely set arc length, and its two circumferential ends form a left stop end face and a right stop end face respectively. When unfolded and positioned, the side positioning block of the spring clip 4 abuts tightly with the right stop end face. This abutting position limits the angle of the left folding ruler 2 relative to the main ruler 1, so that the left folding ruler 2 and the right folding ruler 3 are in a strictly parallel state, thereby ensuring the drawing accuracy.

[0029] In a preferred embodiment, to achieve fast and highly reliable locking, an operation button is provided on the upper part of the spring latch 4. The operation button part of the spring latch 4 is located in the keyway, and the top surface of the operation button is not higher than the upper surface of the main scale 1. The side wall of the operation button forms a locking friction surface. The material of the locking friction surface is preferably a wear-resistant material with a high coefficient of friction. The spring latch 4 is pushed upward under the action of the elastic reset member, so that the locking friction surface is tightly pressed against the inner wall of the keyway of the main scale 1. The strong friction force is used to prevent the left folding ruler 2 from sliding on the main scale 1, so as to achieve precise locking of the position. When the operation button is pressed, the spring latch 4 sinks, the locking friction surface disengages from the contact with the inner wall of the keyway, the friction force is released, and the sliding state is restored.

[0030] As a preferred embodiment, in order to facilitate reading and improve accuracy, the high-precision scale lines etched on the upper surface of the main scale 1 are preferably fine scale lines etched by laser, and the reading bevel provided at the lower edge of the left folding scale 2 is preferably made of a smooth transparent material, and the bevel is flush with the scale lines. This design is used to eliminate parallax when reading with the human eye, so that the reading reference surface can be as close as possible to the high-precision scale lines.

[0031] As a preferred embodiment, in order to ensure portability after folding, the lengths of the left folding ruler 2 and the right folding ruler 3 are designed to be equal, and the size and position of the storage slot opened on the bottom surface of the main ruler 1 are configured such that, in the folded state, the left folding ruler 2 and the right folding ruler 3 can be stored in the storage slot respectively, so that the folded three-fold scale ruler has the smallest overall size.

[0032] As a preferred embodiment, in order to ensure the stability of the right folding ruler 3 when unfolded and positioned, the fixing pin 6 is fixedly connected to the main ruler 1 by a countersunk pin shaft. The positioning end face set at the connection of the right folding ruler 3 has high flatness. When it is in contact with the right end face of the main ruler 1, it can ensure that the right folding ruler 3 has no shaking or gap in the unfolded state, thus ensuring the stability of the drawing reference line.

[0033] In a preferred embodiment, in order to provide stable support during the sliding and locking process, the guide hole of the main ruler 1 adopts a stepped structure. This structure allows the lower part of the spring latch 4 to form a support fit with the lower inner wall of the guide hole, preventing the left folding ruler 2 from tilting or jamming during sliding and locking, and ensuring smooth sliding and reliable locking.

[0034] Working principle: When drawing is required, the right folding ruler 3 is first unfolded and positioned. With the fixing pin 6 as the rotation axis, the right folding ruler 3 is rotated clockwise until the positioning end face of the right folding ruler 3 is physically in contact with the right end face of the main ruler 1. At this time, the right folding ruler 3 is positioned and its position serves as the reference boundary of one side of the drawing.

[0035] Then, the left folding ruler 2 is unfolded and rotated clockwise. Since the boss structure in the groove of the left folding ruler 2 is tightly engaged with the mortise at the lower end of the limiting shaft 5, the left folding ruler 2 drives the limiting shaft 5 to rotate synchronously. During this process, the spring clip 4 housed inside the limiting shaft 5 remains relatively stationary. The side limiting block on the side of the spring clip 4 slides relative to each other in the arc-shaped limiting groove of the limiting shaft 5. When the rotation reaches the preset angle, the side limiting block transitions from the left stop end face of the arc-shaped limiting groove and finally abuts against the right stop end face. This mechanical limiting action prevents the left folding ruler 2 from continuing to rotate, thereby ensuring that the left folding ruler 2 and the locked right folding ruler 3 maintain a strictly parallel state.

[0036] After unfolding, adjust the spacing of parallel lines according to the drawing requirements. At this time, the spring clip 4 is in the unlocked state, the locking friction surface is separated from the keyway of the main scale 1, and the left folding scale 2 is pushed to drive the limit shaft 5 and the spring clip 4 to slide along the guide hole of the main scale 1. By observing the alignment of the reading slope at the lower end of the left folding scale 2 with the high-precision scale line on the surface of the main scale 1, the distance of the parallel lines to be drawn can be accurately determined.

[0037] After the left folding ruler 2 moves to the target scale position, press down the operation button on the top of the spring clip 4 to trigger the internal locking mechanism. Under the action of the elastic reset component, the spring clip 4 springs up, causing the locking friction surface of the side wall to be tightly pressed against the inner wall of the keyway in the guide hole of the main ruler 1. The high static friction generated by the contact surface overcomes the sliding tendency and firmly locks the left folding ruler 2 in the current position to prevent displacement during the drawing and drawing process.

[0038] If the spacing needs to be adjusted again, press the operation button again. The spring clip 4 will fall back, locking the friction surface from contacting the inner wall of the keyway, eliminating frictional resistance. The left folding ruler 2 will return to its sliding state, allowing for the next position adjustment and locking operation, ultimately achieving the drawing of high-precision parallel lines with arbitrary spacing.

[0039] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A three-fold scale ruler specifically for mechanical or engineering drawing, comprising: The main scale (1) has a guide through hole extending along the length direction, and a keyway is recessed on the inner side wall of the guide through hole. The right folding ruler (3) is rotatably connected to the right end of the main ruler (1) by a fixing pin (6); Its features are: The three-fold scale also includes a left-folding scale (2), a limiting shaft (5), and a spring clip (4). The connecting end of the left folding ruler (2) is provided with a groove, and the limiting shaft (5) is received and fixed in the groove. The left folding ruler (2) is slidably connected to the guide hole of the main ruler (1) through the limiting shaft (5) and the spring clip (4). The inner bottom surface of the groove is provided with a boss structure, and the lower end of the limiting shaft (5) is provided with a mortise that matches the boss structure. The boss structure is embedded in the mortise to form a fixed fit, so that the left folding ruler (2) can drive the limiting shaft (5) to rotate synchronously relative to the spring tenon (4). The limiting shaft (5) has a receiving cavity along the axial direction, and the side wall of the limiting shaft (5) has an arc-shaped limiting groove that communicates with the receiving cavity; The spring clip (4) is movably inserted into the guide hole of the main scale (1) and extends downward into the receiving cavity of the limiting shaft (5). The side of the spring clip (4) is provided with a side limiting block, which is slidably fitted in the arc-shaped limiting groove to limit the rotation angle of the limiting shaft (5). The upper part of the spring clip (4) is provided with an operation button, and the side wall of the operation button is provided with a locking friction surface. The spring clip (4) is configured such that: in the natural state, its upper structure abuts against the inner wall of the keyway of the main scale (1) to lock the position; and in the state of being pressed by external force, the locking friction surface disengages from the keyway to release the lock.

2. The three-fold scale ruler for mechanical or engineering drawing as described in claim 1, characterized in that, The spring clip (4) is provided with an elastic reset member inside. One end of the elastic reset member abuts against the inner wall of the spring clip (4), and the other end abuts against the relevant fixing part of the limiting shaft (5) or the main scale (1). The elastic reset member provides elastic force to reset the spring clip (4) upward and press it into the keyway.

3. The three-fold scale ruler for mechanical or engineering drawing as described in claim 1, characterized in that, The arc-shaped limiting groove has a left stop end face and a right stop end face. When the left folding ruler (2) is rotated clockwise to the unfolded state parallel to the right folding ruler (3), the side limiting block of the spring tenon (4) abuts against the right stop end face.

4. The three-fold scale ruler for mechanical or engineering drawing as described in claim 1, characterized in that, The guide hole of the main scale (1) has a stepped structure. The keyway is located in the upper wide opening area of ​​the guide hole. The operation button part of the spring clip (4) is located in the keyway, and the top surface of the operation button is not higher than the upper surface of the main scale (1).

5. The three-fold scale ruler for mechanical or engineering drawing as described in claim 1, characterized in that, The right folding ruler (3) has a positioning end face at the connection point. When the right folding ruler (3) rotates clockwise around the fixing pin (6) to the unfolded position, the positioning end face of the right folding ruler (3) is closely fitted with the right end face of the main ruler (1).

6. The three-fold scale ruler for mechanical or engineering drawing as described in claim 1, characterized in that, The upper surface of the main scale (1) is etched with high-precision scale lines along the length direction, and the lower edge of the left folding scale (2) is provided with a reading slope, which is in close contact with the high-precision scale lines of the main scale (1) in the assembled state.

7. The three-fold scale ruler for mechanical or engineering drawing as described in claim 1, characterized in that, The left folding ruler (2) and the right folding ruler (3) are of equal length, and the bottom surface of the main ruler (1) is provided with a storage groove for storing the left folding ruler (2) and the right folding ruler (3).

8. The three-fold scale ruler for mechanical or engineering drawing as described in claim 1, characterized in that, The fixing pin (6) is a countersunk pin. The fixing pin (6) passes through the right folding ruler (3) and is fixed on the main ruler (1). The end of the fixing pin (6) does not protrude from the surface of the right folding ruler (3).

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