Engine cylinder head milling jig

Abstract

The utility model relates to the technical field of engine manufacturing, especially a kind of fixture for milling engine cylinder cover, including base and pressing plate, wherein, the pressing plate is detachably provided with several at the top of base;Elastic telescopic pin is equipped on the side end of pressing plate, and elastic telescopic pin can only be elastically telescopic along horizontal direction;The free end of elastic telescopic pin is used to insert into the process prefabricated hole of cylinder cover side portion, and is used to compact the cylinder cover;The utility model provides a kind of fixture for milling engine cylinder cover, it is integrated elastic telescopic pin on pressing plate, it is convenient to use the process prefabricated hole of cylinder cover body as positioning reference, and the mechanical constraint structure of " compacting + embedding " is formed by the insertion of pin and hole, and the accurate limit of X, Y direction is realized simultaneously in compacting process, fundamentally inhibits the transverse slip and the tendency of rotation loosening of pressing plate.

Description

Technical Field

[0001] This utility model relates to the field of engine manufacturing technology, and in particular to a jig for milling engine cylinder heads. Background Technology

[0002] In the engine manufacturing process, the cylinder head, as the integrated carrier of the combustion chamber, valve mechanism and cooling system, has its sealing surface, valve guide hole and combustion chamber concave surface machining accuracy directly determining the overall compression ratio consistency and emission performance of the engine.

[0003] During the milling process, the cylinder head needs to be firmly fixed to the machine tool table with the help of a special fixture. At present, the mainstream is still the pressure plate type fixture based on the screw clamping principle, such as the structure disclosed in a pressure plate fixture (application publication number CN104476268A): several vertical screws are set on the fixture base, and the screws are connected to the lateral boss of the cylinder head by the pressure plate, and the preload is applied by the nut to achieve clamping.

[0004] However, existing fixtures have some problems in practical applications. For example, the surface of the cylinder head casting boss has a draft angle, flash burrs and micro-unevenness, which causes the actual contact between the clamping end of the pressure plate and the top surface of the boss to be point or line contact. This makes it very easy for the pressure plate to warp under the pulsation of cutting force, resulting in vibration marks on the machined surface, dimensional deviations, and even safety hazards such as the pressure plate flying off. Utility Model Content

[0005] In view of this, this utility model proposes a jig for milling engine cylinder heads. By integrating an elastic telescopic pin into the pressure plate, it facilitates the use of existing pre-drilled holes in the cylinder head body as positioning references. The pin and hole interlock to form a "clamping + fitting" mechanical constraint structure, simultaneously achieving precise positioning in the X and Y directions during clamping, fundamentally suppressing the lateral slippage and rotational loosening of the pressure plate. This solves the problem of insufficient clamping stability of traditional jigs in dynamic machining environments, significantly improving the machining consistency and process safety of key cylinder head surfaces.

[0006] The technical solution of this utility model is implemented as follows: This utility model provides a fixture for milling engine cylinder heads, including a base and a pressure plate, wherein... Several pressure plates are detachably provided on the top of the base; The pressure plate is provided with an elastic telescopic pin on its side end, and the elastic telescopic pin can only elastically extend and retract in the horizontal direction. The free end of the elastic telescopic pin is used to insert into the pre-fabricated hole on the side of the cylinder head and to press the cylinder head together.

[0007] Based on the above technical solutions, preferably, the pressure plate has a countersunk hole on its side end, and the elastic telescopic pin includes a pin and a spring, wherein... The spring is placed in the countersunk hole; One end of the pin is slidably disposed in the countersunk hole and elastically resists one end of the spring, while the other end is inserted into the pre-fabricated hole.

[0008] Based on the above technical solution, preferably, a first fixing hole is provided on the bottom of the countersunk hole, and a second fixing hole is provided on the end of the pin near the spring, wherein... One end of the spring is embedded in the first fixing hole, and the other end is embedded in the second fixing hole.

[0009] Based on the above technical solutions, preferably, the outer diameter of the pin is less than or equal to the inner diameter of the pre-fabricated hole.

[0010] Based on the above technical solutions, preferably, the elastic telescopic pin further includes a conical plastic cylinder, wherein, The end of the pin away from the spring is fixed to a central post, and the conical plastic cylinder is sleeved on the outside of the central post; The outer diameter of the conical plastic cylinder near the pin is greater than the outer diameter of the other end, and the outer diameter of the conical plastic cylinder near the spring is equal to the outer diameter of the pin.

[0011] Based on the above technical solutions, preferably, one end of the pressure plate with the countersunk hole is in transverse contact with the cylinder head surface located around the process pre-fabrication hole.

[0012] Based on the above technical solutions, preferably, each of the pressure plates is provided with a screw, a nut, and a support rod, wherein, The pressure plate is provided with a waist-shaped hole; The screw is fixed to the top of the base and passes through the waist-shaped hole from top to bottom; The nut is screwed onto the screw rod, and its bottom abuts against the top of the pressure plate. The support rod is screwed to the top of the base, and its top abuts against the bottom of the pressure plate at the end away from the cylinder head.

[0013] Based on the above technical solutions, preferably, the base has a threaded hole that runs vertically through it, wherein... The support rod is screwed into the threaded hole.

[0014] Based on the above technical solutions, preferably, the upper end of the support rod is provided with a flange on its side, wherein, The flange is used to support the bottom of the pressure plate at the end away from the cylinder head; The upper end of the support rod is positioned inside the waist-shaped hole.

[0015] Based on the above technical solutions, a preferred embodiment further includes several supporting components and several locating pins, wherein... Both the support member and the positioning pin are fixed to the top of the base; The top of the support component and the bottom of the cylinder head abut against each other vertically. The top of the locating pin is inserted into the pre-fabricated hole at the bottom of the cylinder head.

[0016] The jig for milling engine cylinder heads according to this utility model has the following advantages over the prior art: (1) By setting the insertion and matching of elastic telescopic pins and pre-made process holes, and by pressing the cylinder head with elastic telescopic pins, it is convenient to use the existing pre-made process holes of the cylinder head body as positioning references to mechanically limit the cylinder head in the X and Y directions, forming a mechanical constraint structure of "pressing + fitting". During the pressing process, the precise limit in the X and Y directions is realized simultaneously, which fundamentally suppresses the lateral slippage and rotation loosening trend of the pressure plate, significantly improves the anti-lateral slippage capability of the fixture in the cutting vibration environment, effectively prevents the pressure plate from tilting and flying off, and improves the machining accuracy and operation safety.

[0017] (2) By adding a conical plastic cylinder to the front end of the pin, the conical surface guides the automatic alignment and compensates for hole position deviation; the plastic material provides buffer, reduces insertion impact, and protects the pre-made holes from being damaged. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a perspective view of the use state of a jig for milling engine cylinder heads according to the present invention; Figure 2 This is a partial perspective view of a jig for milling engine cylinder heads according to the present invention; Figure 3 This is a partial exploded view of a jig for milling engine cylinder heads according to the present invention; Figure 4 This is a schematic diagram of the internal structure of a countersunk hole; In the diagram: 1. Base; 2. Pressure plate; 3. Screw; 4. Nut; 5. Support rod; 6. Support component; 7. Locating pin; 9. Cylinder head; 21. Elastic telescopic pin; 201. Countersunk hole; 202. Waist-shaped hole; 211. Pin; 212. Spring; 213. Conical plastic cylinder; 501. Flange; 101. Threaded hole; 2011. First fixing hole; 2111. Second fixing hole; 2112. Center column; 901. Process prefabrication hole. Detailed Implementation

[0020] The technical solutions of this utility model will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0021] like Figure 1-4 As shown, the present invention provides a jig for milling engine cylinder heads, comprising a base 1 and a pressure plate 2.

[0022] Among them, several pressure plates 2 are detachably provided on the top of the base 1; the side end of the pressure plate 2 is provided with an elastic telescopic pin 21, which can only be elastically extended and retracted in the horizontal direction; the free end of the elastic telescopic pin 21 is used to insert into the process prefabrication hole 901 on the side of the cylinder head 9 and to press the cylinder head 9.

[0023] The aforementioned pre-fabricated holes 901 are structural holes that already exist in the casting or machining process of the engine cylinder head 9, including but not limited to casting through holes, threaded bottom holes, or locating pin holes, which are necessary process hole structures. They are distributed in multiple positions on the side and bottom of the cylinder head 9. The aforementioned fixture uses the existing pre-fabricated holes 901 on the cylinder head 9 body as a positioning reference. Through the insertion and engagement of the elastic telescopic pin 21 with the pre-fabricated holes 901, and by pressing the cylinder head 9 with the elastic telescopic pin 21, the cylinder head 9 is mechanically limited in the X and Y directions. This creates a composite constraint structure of "pressing + fitting", which fundamentally suppresses the lateral slippage and rotational loosening tendency of the pressure plate 2 under cutting vibration, significantly improves the fixture's anti-disturbance capability, effectively prevents the pressure plate 2 from tilting or flying off, and improves machining accuracy and operational safety.

[0024] Several pressure plates 2 are arranged evenly or asymmetrically around the cylinder head 9, corresponding to the pre-fabricated holes 901 at different positions, to ensure a balanced distribution of clamping force and avoid cylinder head deformation caused by local stress concentration.

[0025] In the aforementioned jig for milling engine cylinder heads, a countersunk hole 201 is provided on the side end of the pressure plate 2, and the elastic telescopic pin 21 includes a pin 211 and a spring 212. The spring 212 is placed in the countersunk hole 201 to provide elastic restoring force in the horizontal direction. One end of the pin 211 is slidably disposed in the countersunk hole 201 and elastically abuts against one end of the spring 212, while the other end engages with the pre-made process hole 901 when pressed.

[0026] The countersunk hole 201 guides the pin 211, ensuring it moves only horizontally and preventing misalignment or jamming. The spring force of the spring 212 keeps the pin 211 in an extended state when not inserted. During the clamping process, the spring force prevents the pre-drilled hole 901 on the side of the cylinder head 9 from being damaged by the end of the pin 211.

[0027] To enhance the installation stability of the spring 212, a first fixing hole 2011 is provided on the bottom of the countersunk hole 201, and a second fixing hole 2111 is provided on the end of the pin 211 near the spring 212. One end of the spring 212 is embedded in the first fixing hole 2011, and the other end is embedded in the second fixing hole 2111, forming a double-end limiting structure. This effectively prevents the spring 212 from axially shifting or becoming unstable during repeated compression and rebound, ensuring a stable elastic force transmission path, improving the repeatability and service life of the pin 211, and is especially suitable for long-term operation under high-frequency vibration conditions. At the same time, it also prevents the pin 211 from coming out of the countersunk hole 201, improving the stability of the structural fit.

[0028] To achieve a reliable and low-stress fit between pin 211 and the pre-drilled process hole 901, the outer diameter of pin 211 is set to be less than or equal to the inner diameter of the pre-drilled process hole 901, and the clearance between the two is controlled within the range of 0 to 0.04 mm. This dimension allows pin 211 to be smoothly inserted even when the pre-drilled process hole 901 has certain casting deviations or surface burrs, improving the process tolerance and clamping success rate of the fixture, avoiding pin jamming or cylinder head hole damage due to interference fit, and ensuring the stability of the production cycle.

[0029] Furthermore, the elastic telescopic pin 21 also includes a conical plastic cylinder 213. A central post 2112 is fixed to the end of the pin 211 furthest from the spring 212. The conical plastic cylinder 213 is fitted over the central post 2112, and the two are coaxially aligned and bonded together. The outer diameter of the conical plastic cylinder 213 near the pin 211 is larger than the outer diameter of the other end, and the outer diameter of the conical plastic cylinder 213 near the spring 212 is equal to the outer diameter of the pin 211.

[0030] During insertion, the inclined surface of the tapered plastic cylinder 213 first contacts the edge of the pre-drilled process hole 901, and automatic alignment is achieved through the guidance of the inclined surface, compensating for hole position deviation. The plastic material (such as nylon plastic) has elastic and low friction properties, which can buffer the insertion impact and protect the surface of the cylinder head 9 from direct impact by the metal pin, which is beneficial to the protection of the pre-drilled process hole 901.

[0031] In the aforementioned jig for milling engine cylinder heads, each pressure plate 2 is equipped with a screw 3, a nut 4, and a support rod 5. The pressure plate 2 has a slotted hole 202. The screw 3 is fixed to the top of the base 1 and passes through the slotted hole 202 vertically. The nut 4 is screwed onto the screw 3, and its bottom abuts against the top of the pressure plate 2 vertically. The support rod 5 is screwed onto the top of the base 1, and its top abuts against the bottom of the pressure plate 2 at the end furthest from the cylinder head 9.

[0032] This structure forms a "lever-type" clamping mechanism. During clamping, pressure is applied through the nut 4, and the support rod 5 provides a fulcrum to achieve stable clamping. The waist-shaped hole 202 allows the pressure plate 2 to be finely adjusted in the horizontal direction, adapting to the clamping point distribution of different cylinder head models, improving the versatility of the fixture, and facilitating the insertion of the pin 211 and the pre-fabricated process hole 901.

[0033] In this structure, the support rod 5 is a threaded rod structure, and its outer diameter is smaller than the inner diameter of the waist-shaped hole 202. A threaded hole 101 is vertically provided on the base 1, wherein the support rod 5 is screwed into the threaded hole 101. The height of the support rod 5 is adjusted by the screwing depth so that its top precisely supports the designated position of the pressure plate 2, ensuring a balanced clamping torque.

[0034] Furthermore, a flange 501 is provided on the side of the upper end of the support rod 5, which is used to support the bottom of the pressure plate 2 away from the cylinder head 9. At the same time, the upper end of the support rod 5 is placed inside the waist-shaped hole 202, and the flange 501 can prevent the support rod 5 from accidentally coming off during vibration. This structure not only provides reliable support, but also limits the lateral displacement tendency of the pressure plate 2, enhances the torsional stiffness of the overall clamping system, and improves the dynamic machining stability.

[0035] The aforementioned jig for milling engine cylinder heads also includes several support members 6 and several locating pins 7 fixed to the top of the base 1. The tops of the support members 6 abut against the bottom of the cylinder head 9, providing uniform support and preventing deformation of the cylinder head 9 during clamping. The tops of the locating pins 7 engage with the pre-drilled holes 901 on the bottom of the cylinder head 9, forming a precise positioning reference of "one surface and two pins," ensuring consistent positioning of the cylinder head 9 during each clamping operation. This structure, in conjunction with the elastic telescopic pins 21 on the pressure plate 2, constitutes a multi-point collaborative positioning and clamping system, resulting in high clamping accuracy and meeting the process requirements of high-precision CNC milling.

[0036] During clamping, the end of the pressure plate 2 with the countersunk hole 201 is placed against the surface of the cylinder head 9 around the process pre-fabricated hole 901 in a transverse abutment. Specifically, before clamping, the end of the pressure plate 2 with the countersunk hole 201 is placed against the surface of the cylinder head 9 around the process pre-fabricated hole 901, and then the nut 4 is tightened. After tightening, the cylinder head 9 is laterally limited through this structure, which improves the fixing effect of the cylinder head 9.

[0037] The method of using the jig for milling engine cylinder heads according to this utility model is as follows: First, place the cylinder head 9 on top of the support 6, and insert the pre-drilled hole 901 at its bottom into the locating pin 7. Then, move the pressure plate 2 towards the cylinder head 9, so that the free end of the elastic telescopic pin 21 is inserted into the pre-drilled hole 901 on the side of the cylinder head 9. After insertion, apply pressure through the nut 4, and the support rod 5 provides a fulcrum, causing the pressure plate 2 to move downward, driving the elastic telescopic pin 21 to perform a downward pressing action, thereby pressing the cylinder head 9 along the Z direction through the elastic telescopic pin 21.

[0038] The above are merely preferred embodiments of this utility model and are not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A jig for milling engine cylinder heads, characterized in that: Includes a base (1) and a pressure plate (2), wherein, Several pressure plates (2) are detachably provided on the top of the base (1); The pressure plate (2) is provided with an elastic telescopic pin (21) on its side end. The elastic telescopic pin (21) can only elastically extend and retract in the horizontal direction. The free end of the elastic telescopic pin (21) is used to insert into the process pre-made hole (901) on the side of the cylinder head (9) and to press the cylinder head (9) together.

2. The jig for milling engine cylinder heads as described in claim 1, characterized in that: The pressure plate (2) has a countersunk hole (201) on its side end, and the elastic telescopic pin (21) includes a pin (211) and a spring (212), wherein, The spring (212) is placed in the countersunk hole (201); One end of the pin (211) is slidably disposed in the countersunk hole (201) and elastically resists one end of the spring (212), while the other end is inserted into the prefabricated hole (901).

3. The jig for milling engine cylinder heads as described in claim 2, characterized in that: The bottom of the countersunk hole (201) is provided with a first fixing hole (2011), and the end of the pin (211) near the spring (212) is provided with a second fixing hole (2111). One end of the spring (212) is embedded in the first fixing hole (2011), and the other end is embedded in the second fixing hole (2111).

4. The jig for milling engine cylinder heads as described in claim 2, characterized in that: The outer diameter of the pin (211) is less than or equal to the inner diameter of the pre-fabricated hole (901).

5. The jig for milling engine cylinder heads as described in claim 2, characterized in that: The elastic telescopic pin (21) also includes a conical plastic cylinder (213), wherein, The pin (211) is fixed to a central post (2112) at the end away from the spring (212), and the conical plastic cylinder (213) is sleeved on the outside of the central post (2112); The outer diameter of the conical plastic tube (213) near the pin (211) is greater than the outer diameter of the other end, and the outer diameter of the conical plastic tube (213) near the spring (212) is equal to the outer diameter of the pin (211).

6. The jig for milling engine cylinder heads as described in claim 2, characterized in that: The end of the pressure plate (2) with the countersunk hole (201) is in transverse contact with the surface of the cylinder head (9) located around the process pre-fabrication hole (901).

7. The jig for milling engine cylinder heads as described in claim 1, characterized in that: Each of the pressure plates (2) is provided with a screw (3), a nut (4), and a support rod (5), wherein, The pressure plate (2) is provided with a waist-shaped hole (202); The screw (3) is fixed to the top of the base (1) and passes through the waist-shaped hole (202) from top to bottom. The nut (4) is screwed onto the screw (3), and its bottom abuts against the top of the pressure plate (2); The support rod (5) is screwed to the top of the base (1), and its top abuts against the bottom of the pressure plate (2) at the end away from the cylinder head (9).

8. The jig for milling engine cylinder heads as described in claim 7, characterized in that: The base (1) has a threaded hole (101) that runs vertically through it. The support rod (5) is screwed into the threaded hole (101).

9. A jig for milling engine cylinder heads as described in claim 7, characterized in that: The upper end of the support rod (5) is provided with a flange (501) on its side, wherein, The flange (501) is used to support the bottom of the pressure plate (2) away from the cylinder head (9); The upper end of the support rod (5) is placed inside the waist-shaped hole (202).

10. A jig for milling engine cylinder heads as described in claim 7, characterized in that: It also includes several support components (6) and several locating pins (7), wherein, The support (6) and the positioning pin (7) are both fixed to the top of the base (1); The top of the support member (6) and the bottom of the cylinder head (9) abut against each other vertically; The top of the positioning pin (7) is inserted into the pre-fabricated hole (901) at the bottom of the cylinder head (9).

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