Clamping device for injection molding machine

Abstract

The present invention relates to a technique capable of relieving stress concentration in a fastening structure of a half nut and a tie bar. The present invention provides a clamping device for an injection molding machine, comprising a half nut having a plurality of nut teeth that protrude along the circumference of the inner peripheral surface thereof, and a plurality of nut valleys recessed between the plurality of nut teeth, wherein at least some of the plurality of nut valleys have different valley widths. According to the present invention, clamping force is stably maintained such that the quality of a molded product can be improved.

Description

Mold clamping device for injection molding machine

[0001] The present invention relates to an injection molding machine, and more specifically to a mold clamping device.

[0002] An injection molding machine is equipment used to obtain a molded product by injecting molten raw material into a cavity of the product shape within a mold.

[0003] An injection molding machine includes a mold clamping device and an injection device.

[0004] The molding device forms a cavity having the shape of a molded product to allow the molded product to be molded, or opens the cavity so that the molded product can be withdrawn.

[0005] An injection molding device is configured to melt material and inject it into a cavity through a nozzle so that the molding of a product can take place.

[0006] Among these, the mold clamping device plays an essential role in opening and closing the mold and sealing it at a predetermined pressure during the molding cycle to form a molded product without resin leakage.

[0007] FIG. 1 is a reference diagram for explaining a conventional molding device.

[0008] Referring to FIG. 1, the molding device (10) may include a fixed plate (11), a movable plate (12), a fixed mold (13), a movable mold (14), a tie bar (15), and a half nut (16).

[0009] The fixed plate (11) is installed adjacent to the injection device, but is fixed at one point.

[0010] The movable plate (12) is positioned facing the fixed plate (11) and can be moved in a direction closer to or further away from the fixed plate (11) by a moving device (not shown).

[0011] A first molding area (C1) forming part of the cavity (C) is formed in the fixed mold (13).

[0012] The fixed mold (13) is coupled to the fixed plate (11), and is positioned so that one side having the first molding area (C1) formed faces the movable plate (12).

[0013] In the movable mold (14), a second molding area (C2) is formed, which forms another part of the cavity (C).

[0014] The movable mold (14) is coupled to the movable plate (12), and is positioned so that one side having the second molding area (C2) formed faces the fixed plate (11).

[0015] The movable mold (14) can be moved closer to or further away from the fixed mold (13) depending on the movement of the movable plate (12).

[0016] The tie bar (15) guides the movable plate (12). The movable plate (12) slides along the tie bar (15) and can be moved in a direction closer to or further away from the fixed plate (11).

[0017] At least a portion of the tie bar (15) has a number of teeth (hereinafter referred to as ‘tie bar teeth (15-T)’) formed at regular intervals to be fastened with a half nut (16).

[0018] The half nut (16) is installed on the movable plate (12) side and can function to lock the position of the movable plate (12).

[0019] Half nuts (16) are arranged such that two semicircular nuts (hereinafter referred to as ‘first nut (16-1)’ and ‘second nut (16-2)’) surround the outer circumference of the tie bar (15).

[0020] On the inner surface of each of the first nut (16-1) and the second nut (16-2), a plurality of teeth (hereinafter referred to as 'nut teeth (16-T)') capable of engaging with the teeth (15-T) of the tie bar are formed at a predetermined interval.

[0021] In the closed state, the half nut (16) can be fastened to the tie bar (15) in a cross-shaped state between the nut tooth (16-T) and the tie tooth (15-T) as the first nut (16-1) and the second nut (16-2) come into contact with the outer surface of the tie bar (15).

[0022] When the half nut (16) and the tie bar (15) are connected, the position of the movable plate (12) is fixed.

[0023] Conversely, when the first nut (16-1) and the second nut (16-2) are separated from the outer surface of the tie bar (15) and the connection with the tie bar (15) is released, the movable plate (12) becomes movable.

[0024] During the process of the half nut (16) being fastened to the tie bar (15), the tie bar (15) is tensioned in one direction opposite to the position of the fixed plate (11). When the fastening between the half nut (16) and the tie bar (15) is completed, a clamping force is applied to the molds (13, 14) by the elastic restoring force of the tensioned tie bar (15).

[0025] During this process, most of the load is applied to some of the interlocking teeth located close to the movable plate (12). If stress is concentrated on some of the interlocking teeth provided in the half nut (16), the following problems may occur.

[0026] First, some of the meshing teeth where stress is concentrated may wear out prematurely. If some of the meshing teeth where stress is concentrated wear out or are damaged during repeated operation, the connection between the tie bar (15) and the half nut (16) may become unstable.

[0027] Second, if the connection between the tie bar (15) and the half nut (16) is unstable, it is difficult to transmit the intended clamping force to the mold (13, 14). As a result, the mold (13, 14) may not be completely closed, which could lead to a defect in the quality of the molded product.

[0028] Third, as the fatigue life of the tie bar (15) and half nut (16) is shortened due to continuous load during repeated operation, breakage was inevitable.

[0029] [Prior Art Literature]

[0030] [Patent Literature]

[0031] (Patent Document 1) Chinese Registered Utility Model Publication No. 203228380

[0032] The present invention was conceived from consideration of a structure capable of alleviating stress concentration.

[0033] To achieve this purpose, a mold clamping device (100) for an injection molding machine according to one embodiment of the present invention comprises: a fixed plate (110) to which a fixed mold (FM) is coupled; a movable plate (120) which is positioned facing the fixed plate (110) and moves in a direction closer to or further away from the fixed plate (110), and to which a movable mold (MM) is coupled to one surface facing the fixed mold (110); a tie bar (141) for guiding the movement of the movable plate (120); and a half nut (151) coupled to the tie bar (141) to restrict or allow the movement of the movable plate (120). The tie bar (141) is provided with a fastening portion (141-CP) for fastening with the half nut (151) in at least a portion of the tie bar (141), and a plurality of tie bar grooves (TV) are formed by being recessed to a predetermined depth along the circumference of the outer surface of the tie bar (141), and the half nut (151) has a plurality of nut teeth (NT) protruding along the circumference of the inner surface and a plurality of nut grooves (NV) formed by being recessed between the plurality of nut teeth (NT), and the half nut (151) is fastened with the fastening portion (141-CP) as the plurality of nut teeth (NT) are inserted to a predetermined depth into at least some of the tie bar grooves (TV), and at least some of the nut grooves (NV) located close to the movable plate (120) among the plurality of nut grooves (NV) may have a groove width different from the remaining nut grooves (NV).

[0034] The pitch, which is the horizontal distance from the reference point of one of the multiple nut teeth (NT) to the reference point of another nut tooth (NT) located adjacent to it, can all be the same.

[0035] The above multiple nut grooves (NV) may have a wider groove width the closer they are to the movable plate (120).

[0036] The above multiple nut teeth (NT) may have a narrower tooth width the closer they are to the movable plate (120).

[0037] Among the plurality of nut grooves (NV), the groove width of at least three nut grooves (NV) adjacent to the movable plate (120) is different from the groove width of the remaining nut grooves (NV), and the groove width may be wider the closer it is to the movable plate (120).

[0038] Among the plurality of nut teeth (NV), the tooth width of at least three nut teeth (NT) adjacent to the movable plate (120) is different from the tooth width of the remaining nut teeth (NT), and the tooth width may be narrower the closer it is to the movable plate (120).

[0039] As explained above, according to the present invention, the following effects can be derived.

[0040] First, by adjusting the width of the nut groove formed in the half-nut according to the distance from the movable plate, the stress concentrated in one section due to the clamping force generated when the half-nut and tie bar are fastened can be effectively distributed.

[0041] Second, uniform load distribution is possible across the nut teeth formed throughout the entire length of the half-nut, which can improve durability and lifespan.

[0042] Third, by adjusting the nut groove and groove width formed in the half nut and keeping the pitch constant, the alignment precision with the tie bar is ensured, and the fastening stability between the tie bar and the half nut can be improved.

[0043] Ultimately, as the clamping force is stably maintained, it can contribute to improving the quality of the molded product.

[0044] FIG. 1 is a reference diagram illustrating a clamping device applied to a conventional injection molding machine.

[0045] FIG. 2 is a schematic diagram illustrating a mold clamping device for an injection molding machine according to one embodiment of the present invention.

[0046] FIG. 3 is a perspective view showing the fastening structure of the tie bar and half nut in the molding device illustrated in FIG. 2.

[0047] FIGS. 4 to 6 are reference drawings illustrating the structure of a half nut in a mold clamping device for an injection molding machine according to one embodiment of the present invention.

[0048] FIGS. 7a and 7b illustrate simulation results exemplified to explain the utility of a half nut applied to a mold clamping device for an injection molding machine according to one embodiment of the present invention.

[0049] Preferred embodiments according to the present invention are described with reference to the accompanying drawings, provided that for the sake of brevity, descriptions of well-known configurations are omitted or compressed as much as possible.

[0050] <Brief Description of Molding Devices>

[0051] FIG. 2 is a schematic diagram illustrating a molding device (100) for an injection molding machine according to one embodiment of the present invention, and FIG. 3 is a perspective view showing the fastening structure of a tie bar (141) and a half nut (151) in the molding device (100) illustrated in FIG. 2.

[0052] Referring to FIGS. 2 and 3, a molding device (100) for an injection molding machine according to one embodiment of the present invention forms a cavity (C) having the shape of a molded product to form the molded product, or opens the cavity (C) so that the molded product can be withdrawn.

[0053] For reference, although not shown in the drawing, an injection device (not shown) is arranged in a line with the molding device (100) and fills the cavity (C) formed by the molding device (100) with molten resin.

[0054] For convenience of explanation, the side where the moving device (130) is positioned will be referred to as one side, and the opposite side, the fixed mold (FM) side into which at least a portion of the injection device is inserted and positioned, will be referred to as the other side.

[0055] The molding device (100) includes a fixed plate (110), a fixed mold (FM), a movable plate (120), a movable mold (MM), a moving device (130), a holding device (140), a fixing device (150), etc.

[0056] The fixed plate (110) is installed so as to be fixed at one point. More specifically, the fixed plate (110) is positioned facing the injection device and is installed so as to be fixed to a base frame (not shown) that supports the molding device (100) and the injection device.

[0057] An insertion hole (110-IH) is formed at the edge of the fixed plate (110) into which the other side of the tie bar (141), which will be described later, is inserted.

[0058] A fixed mold (FM) is attached to one side of the fixed plate (110).

[0059] The movable plate (120) is positioned facing the fixed plate (110) on the opposite side of the fixed plate (110).

[0060] The movable plate (120) is configured to be movable in a direction closer to or further away from the fixed plate (110).

[0061] An insertion hole (120-IH) is formed at the edge of the movable plate (120) so that a portion of the tie bar (141), which will be described later, can be inserted. The four insertion holes (120-IH) in the movable plate (120) correspond to the four insertion holes (120-IH) in the fixed plate (110).

[0062] A movable mold (MM) is attached to the other side of the movable plate (120).

[0063] The movable die (MM) is positioned so that the surface on which the molding area forming part of the cavity (C) is formed faces the fixed die (FM).

[0064] The movable mold (MM) moves together with the movement of the movable plate (120).

[0065] The moving device (130) moves the movable plate (120) so that the movable plate (120) moves closer to or further away from the fixed plate (110).

[0066] The movable plate (120) is moved by the moving device (130), and the spacing between the mutually facing molds (FM, MM) is adjusted.

[0067] A retainer (140) is provided to maintain the shape force when injection is performed.

[0068] The retainer (140) includes a tie bar (141) and a tie bar piston (142).

[0069] The tie bar (141) is configured to guide the movement of the movable plate (120).

[0070] The tie bar (141) is connected to a hydraulic cylinder (142) with one side passing through the insertion hole (110-IH) of the fixed plate (110), and is configured so that one side passes through the insertion hole (120-IH) of the movable plate (1210).

[0071] One side of the tie bar (141) is provided with a fastening portion (141-CP) for fastening with a half nut (151).

[0072] In the fastening portion (141-CP), a plurality of tie bar grooves (TV) are formed by being recessed to a predetermined depth along the circumference of the outer surface of the tie bar (141) and spaced apart at regular intervals.

[0073] A Tie-Bachi (TT) is formed between neighboring Tie-Bagols (TVs).

[0074] The spacing of the TVs is all the same.

[0075] The diameter (d1) of the tie bar (TT) is smaller than the diameter (d2) of the tie bar bone (TV), but is provided to be equal to the diameter (d3) of the remaining part of the tie bar (141) excluding the fastening part (141-CP).

[0076] The tie-piston (142) can be provided as a hydraulic cylinder.

[0077] The tie bar piston (142) hydraulically pulls or releases the tie bar (141).

[0078] When the tie bar piston (142) pulls the tie bar (141), the tie bar (141) is stretched to a predetermined length. When the position of the movable plate (120) is fixed by the fixer (150) described later while the tie bar (141) is stretched, a clamping force is applied in the direction of bringing the molds (FM, MM) into close contact with each other by the elastic restoring force that attempts to restore the tie bar (141) to its original length.

[0079] When the injection is completed, the tie bar piston (142) releases the tension applied to the tie bar (141), allowing the movable plate (120) to move according to the injection process.

[0080] The tie-piston (142) is connected to the fixed plate (110).

[0081] Four of these retainers (140) are provided and are coupled to four insertion holes (110-IH, 120-IH) formed in the fixed plate (110) and the movable plate (120), respectively.

[0082] The fixing device (150) securely fastens the movable plate (120) to the tie bar (141) or releases the fastening.

[0083] When the movable plate (120) is secured to the tie bar (141) by the fixing device (150), the movable plate (120) is also pulled by the tie bar piston (142) when the tie bar piston (142) pulls the tie bar (141). As the tie bar (141) and the movable plate (120) are pulled to the other side by the tie bar piston (142), the clamping force applied to the molds (FM, MM) can be maintained.

[0084] On the other hand, when the fixing device (150) releases the connection between the movable plate (120) and the tie bar (141), the movable plate (120) becomes movable by the moving device (130).

[0085] The fixing device (150) includes a half nut (151) and a binding element (152).

[0086] The half nut (151) is positioned on the side of the movable plate (120) to restrict or allow the movement of the movable plate (120).

[0087] The half nut (151) has a number of nut teeth (NT) formed protruding along the circumference of the inner surface and a number of nut grooves (NV) formed in depressions between the number of nut teeth (NT).

[0088] When the half nut (151) restricts the movement of the movable plate (120), a plurality of nut teeth (NT) are inserted to a predetermined depth into at least some of the tie bars (TV) among the plurality of tie bars (TV) and are connected to the fastening portion (141-CP). Subsequently, when the nut teeth (NT) and the tie bars (TV) are separated and the connection between the half nut (151) and the fastening portion (141-CP) is released, the movable plate (120) becomes movable.

[0089] The half nut (151) includes a first nut (151a) and a second nut (151b).

[0090] The first nut (151a) is positioned to wrap around a portion of the tie bar (141).

[0091] The second nut (151b) is positioned to wrap around the remaining part of the tie bar (141).

[0092] When the first nut (151a) and the second nut (151b) are moved toward the center of the tie bar (141) by the binding circle (152), the nut tooth (NT) is inserted into the tie bar groove (TV), and the half nut (151) and the fastening part (141-CP) are fastened together. When the half nut (151) is fastened to the fastening part (141-CP), the movable plate (120) and the tie bar (141) are fastened together.

[0093] When the first nut (151a) and the second nut (151b) are moved outwardly by the binding circle (152) of the tie bar (141), the nut tooth (NT) is separated from the bottom of the tie bar groove (TV), and the connection between the half nut (151) and the fastening part (141-CP) is released. When the connection between the half nut (151) and the fastening part (141-CP) is released, the connection between the movable plate (120) and the tie bar (141) is released.

[0094] The binding member (152) operates the half nut (151) to connect the half nut (151) and the tie bar (141) or to release the connection between the half nut (151) and the tie bar (141).

[0095] Hereinafter, with reference to the drawings, the shape of the half nut (151) in the molding device (100) for an injection molding machine proposed by the present invention will be explained in more detail.

[0096] Explanation of Half Nuts

[0097] FIGS. 4 to 6 are reference drawings illustrating the structure of a half nut (151) in a molding device (100) for an injection molding machine according to one embodiment of the present invention.

[0098] FIG. 4 is an enlarged illustration of the fastening structure of the tie bar (141) and the half nut (151). The following description refers primarily to FIG. 4. In FIG. 4, the number of nut teeth (NT) formed on the half nut (151) is limited to 8, but this is not limited to this number, and it is understood that the number can be increased or decreased depending on the implementation.

[0099] The fastening portion (141-CP) of the tie bar (141) has a plurality of tie bar grooves (TV) formed therein, and between the tie bar grooves (TV), a plurality of tie bars (TT) of a predetermined width are formed.

[0100] The tips of multiple tie bars (TT) are positioned on a virtual horizontal line (VL) that horizontally connects the outer surface of the remaining portion of the tie bar (141), excluding the fastening portion (141-CP). These multiple tie bars (TT) have the same height, and the multiple tie bar grooves (TV) are formed to have the same depth.

[0101] The half nut (151) has a contact portion (151-TP) that contacts the outer surface of the tie bar (141) or the tip of the tie bar (TT) when connected to the fastening portion (141-CP) to restrict the movement of the movable plate (120).

[0102] In the contact portion (151-TP), the nut teeth (NT1, NT2,…, NT8) formed on the inner circumference of the half nut (151) are partially inserted into the tie bar (TV).

[0103] The nut teeth (NT1, NT2, ..., NT8) formed on the inner surface of the half nut (151) are formed to protrude further than the contact portion (151-TP).

[0104] The structure in which the nut teeth (NT1, NT2, ..., NT8) formed on the half nut (151) and the tie bar teeth (TT) are interlocked and fastened allows the half nut (151) to withstand the clamping force (Fc) generated by the tie bar (141) and restrict the movement of the movable plate (120). That is, the tooth structure of the half nut (151) must be able to withstand the difference in the amount of deformation caused by the tension and compression of the tie bar (141) and the half nut (151).

[0105] For reference, during the process of fastening by interlocking the nut teeth (NT1, NT2,…, NT8) formed on the half nut (151) and the tie bar teeth (TT), the deformation direction (Dt) caused by the tie bar (141) and the deformation direction (Dh) caused by the half nut (151) are opposite.

[0106] At this time, the amount of deformation of the first nut tooth (NT1) positioned closest to the movable plate (120) among the nut teeth (NT1, NT2, ..., NT8) is inevitably greater than that of the other nut teeth (NT2 to NT8) that are further away from the movable plate (120). In other words, the closer it is to the movable plate (120), the greater the amount of deformation of the nut tooth (NT) and the amount of deformation of the tie tooth (TT) are inevitably.

[0107] Due to this difference in deformation amount, conventionally, contact stress caused by the clamping force (Fc), the deformation amount of the tie bar (141), and the deformation amount of the half nut (151) was concentrated on the first nut tooth (NT1) placed closest to the movable plate (120) among the nut teeth (NT1, NT2,…, NT8), and the adjacent nut teeth (NT2, NT3). The simulation results for this are exemplified in FIG. 7a. If contact stress is concentrated on the half nut (151), not only is the lifespan of the half nut (151) shortened, but damage to adjacent components may also occur.

[0108] Accordingly, the inventors intended to improve the structure in which teeth mesh between the nut teeth (NT1 to NT3) and the tie bar (TT) adjacent to the movable plate (120) and the phenomenon of contact stress concentration by modifying the tooth profile structure of the half nut (151) when a clamping force (Fc) is applied.

[0109] Before explaining the tooth profile structure of the half nut (151) applied in the present invention, we would first like to define the terms related thereto.

[0110] First, the pitch (P) can be defined as the horizontal distance from the reference point (RP) of any one of the nut teeth (NT1, NT2, …, NT8) formed in the half nut (151) to the reference point (RP) of an adjacent nut tooth (NT).

[0111] The reference point (RP) may be an intersection point where the nut tooth (NT) comes into contact with a virtual horizontal line (VL) that connects the outer surface of the tie bar (141) in a horizontal direction. When viewed with respect to the half nut (151), the virtual horizontal line (VL) for defining the reference point (RP) may be a virtual parallel line that connects the lower surfaces of the contact portions (151-TP) located at both ends of the half nut (151) in a horizontal direction.

[0112] The tooth width (TW) is the width of the nut teeth (NT1, NT2, ..., NT8) formed in the half nut (151). In any one nut tooth (NT), the tooth width (TW) may refer to the horizontal width between the points where it meets a predefined horizontal line (VL).

[0113] The groove width (VW) is the width of the nut grooves (NV1, NV2, …, NV8) formed in the half nut (151). In any one of the nut grooves (NV), the groove width (VW) may refer to the horizontal width between the points that meet a predefined horizontal line (VL).

[0114] Hereinafter, the tooth profile structure of the half nut (151) applied to the present invention will be explained with reference to FIGS. 5 and 6. With reference to FIGS. 5 and 6, a half nut (151) according to one embodiment of the present invention has n (where n is a natural number) nut teeth (NT1, NT2, …, NT n ) and n-1 (where n is a natural number) nut grooves (NV1, NV2, …, NV n-1 ) may be formed.

[0115] First, regarding the example of FIG. 5, in the half nut (151) proposed by the present invention, n-1 nut grooves (NV1, NV2, …, NV n-1At least some of the ) may have different valley widths (VW).

[0116] To explain more specifically, n-1 nut grooves (NV1, NV2, …, NV n-1 ) is wider the closer it is to the movable plate (120), that is, the further it is on the other side (VW1, VW2, …, VW n It has ). In this case, n nut teeth (NT1, NT2, …, NT n ) width(TW1, TW2, …, TW n ) can be the same.

[0117] However, the area close to the movable plate (120) is the section where the greatest deformation and stress occur due to the molding force (Fc).

[0118] n-1 nut grooves (NV1, NV2, …, NV) close to the corresponding section n-1 It is also possible to adjust the groove widths (VW1, VW2, VW3) of at least three nut grooves (NV1, NV2, NV3) adjacent to the movable plate (120). At this time, the groove widths (VW1, VW2, VW3) of the three nut grooves (NV1, NV2, NV3) are wider the closer they are to the movable plate (120). <VW2<VW1)을 가지도록 마련되고, 나머지 너트골들의 골폭은 모두 동일한 골폭을 가지되, 앞서 언급한 3개의 너트골(NV1, NV2, NV3) 보다는 좁은 골폭을 가질 수 있다.

[0119] The closer to the movable plate (120), the n-1 nut grooves (NV1, NV2, …, NV n-1 )'s bone width(VW1>VW2>VW3>…>VW n-1 By designing the ) widely, it corresponds to the deformation amount of different half nuts (151) throughout the entire section and can be fastened to the tie bar (141). The nut teeth (NT1, NT2, …, NT) throughout the entire section n The ) and the tie (TT) can also be made to come into even contact.

[0120] This can alleviate stress concentration and prevent excessive load from being concentrated on a specific nut (NT). Additionally, the fastening structure between the half nut (151) and the tie bar (141) can be maintained more firmly and consistently.

[0121] Next, regarding the example of FIG. 6, in a half nut (151) according to another embodiment of the present invention, n nut teeth (NT1, NT2, …, NT n The pitch (P1, P2, …. P) is the horizontal distance from the reference point of any one of the nut teeth (NT) to the reference point of another nut tooth (NT) located adjacent to it. n-1 ) can all be the same. Pitch(P1, P2, …. P n-1 ) includes one nut tooth (NT) and one adjacent nut groove (NV).

[0122] As illustrated in FIG. 6, in a half nut (151) according to another embodiment of the present invention, n nut teeth (NT1, NT2, …, NT n ) has a narrower width (not shown) the closer it is to the above-mentioned movable plate (120).

[0123] Considering that the area close to the movable plate (120) is the section where the greatest deformation and stress occur due to the clamping force (Fc), n nut teeth (NT1, NT2, …, NT n It is also possible to adjust the tooth width (not shown) of at least three nut teeth (NT1, NT2, NT3) adjacent to the movable plate (120). In this case, the tooth width of the three nut teeth (NT1, NT2, NT3) is arranged to have a narrower tooth width the closer they are to the movable plate (120), and the tooth width of the remaining nut teeth is all the same, but can have a wider tooth width than the three nut teeth (NT1, NT2, NT3) mentioned above.

[0124] However, pitch(P1, P2, …. P n-1As all of them are arranged equally, if the width of the nut tooth (NT1) at a pitch (e.g., P1) is narrow based on one pitch, the width of the nut groove (NV1) is simultaneously wide compared to other nut grooves.

[0125] n nut teeth (NT1, NT2, …, NT) depending on the distance from the movable plate (120) n Adjusting the width of ) and consequently n-1 nut grooves (NV1, NV2, …, NV n-1 )'s bone width(VW1>VW2>VW3>…>VW n-1 By designing the ) to gradually widen as it moves toward the other side, the stress concentrated on the movable plate (120) and some adjacent nut teeth (NT1, NT2, NT3) is dispersed, thereby minimizing the possibility of localized wear or damage. This can extend the lifespan of not only the half-nut (151) but also adjacent components and contribute to reducing maintenance costs.

[0126] In the case of FIG. 6, the widths of the nut teeth (NT) and nut grooves (NV) are adjusted, and the pitch (P1, P2, …. P n-1 As all of them are provided equally, all nut teeth (NT) formed on the half nut (151) can be evenly engaged with the tie bar (TT). That is, the alignment precision between the tooth structure formed on the half nut (151) and the tie bar (TT) formed on the fastening part (141-CP) provided on the tie bar (141) can be guaranteed.

[0127] The utility of the present invention will be explained below with reference to the drawings.

[0128] FIGS. 7a and 7b illustrate simulation results exemplified to explain the utility of a half nut applied to a mold clamping device for an injection molding machine according to one embodiment of the present invention.

[0129] FIG. 7a illustrates the stress distribution generated by the clamping force applied during the fastening of a half nut and a tie bar by applying a tooth profile that was conventionally applied to a half nut.

[0130] In the case of Fig. 7a, the width between the nut teeth, the width between the nut grooves, and the pitch are constant throughout the entire length of the half nut without any adjustment.

[0131] Referring to Fig. 7a, it can be seen that stress is concentrated on some nut teeth close to the movable plate located on the other side.

[0132] FIG. 7b illustrates the stress distribution generated by the clamping force applied during the fastening of the half nut and tie bar proposed by the present invention.

[0133] Referring to FIG. 7b, it can be seen that the stress concentrated on some nut teeth close to the movable plate located on the other side is reduced, and at the same time, the stress burden is distributed to other nut teeth located on one side.

[0134] These simulation results allow for the improvement of the phenomenon where stress is concentrated on certain nut teeth during the fastening of a half nut and a tie bar. In other words, by making the distribution of clamping force between the nut teeth of the half nut and the tie teeth of the tie bar more uniform, the fatigue life of the half nut and the tie bar can be improved.

[0135] If the pitch varies along with the tooth width or groove width adjustment in the half nut, the tie bar tooth and nut tooth having a uniform pitch may come into direct contact during the process of fastening the half nut to the tie bar before applying clamping force, and fastening may be restricted.

[0136] The present invention changes the width of the nut teeth or the width of the nut grooves formed in the half nut, and by fixing the pitch, problems of friction or limited fastening between the half nut and the tie bar that may occur in a variable pitch tooth profile structure can be prevented in advance.

[0137] For reference, the amount of change in the groove width is incremented by a preset increment (χ) from the groove width located on one side to the groove width located on the other side. For example, in the case of the first nut groove located on one side, it is incremented by (N-2) times the increment ((N-2)χ) compared to the n-1th nut groove located on the other side. However, since the increment is at the level of 0.003 mm to 0.016 mm, the tooth profile structure of the half nut exemplified in FIG. 7b may not appear significantly different from FIG. 7a, but the technical features of the present invention are reflected.

[0138] The embodiments described above are merely preferred examples of the present invention and may have various applications. Therefore, the present invention should not be understood as being limited only to the contents described above. Instead, the scope of the present invention should be understood as the separately described claims and their equivalents.

Claims

1. A fixed plate (110) combined with a fixed mold (FM); A movable plate (120) positioned facing the fixed plate (110) and moved in a direction closer to or further away from the fixed plate (110), with a movable mold (MM) attached to one side facing the fixed mold (110); A tie bar (141) for guiding the movement of the above-mentioned movable plate (120); and It includes a half nut (151) coupled to the tie bar (141) to restrict or allow movement of the movable plate (120); and At least a portion of the tie bar (141) is provided with a fastening portion (141-CP) for fastening with the half nut (151), and In the above-mentioned fastening portion (141-CP), a plurality of tie bar grooves (TV) are formed by being recessed to a predetermined depth along the circumference of the outer surface of the tie bar (141). The above half nut (151) has a plurality of nut teeth (NT) formed protruding along the circumference of the inner surface and a plurality of nut grooves (NV) formed in depressions between the plurality of nut teeth (NT). The above half nut (151) is fastened to the fastening portion (141-CP) while the plurality of nut teeth (NT) are inserted to a predetermined depth into at least some of the plurality of tie bars (TV). Among the plurality of nut grooves (NV), at least some of the nut grooves (NV) located close to the movable plate (120) have a groove width different from the remaining nut grooves (NV). Mold clamping device (100) for injection molding machine.

2. In Paragraph 1, The pitch, which is the horizontal distance from the reference point of any one of the multiple nut teeth (NT) to the reference point of another nut tooth (NT) located adjacent to it, is the same for all of them. Mold clamping device (100) for injection molding machine.

3. In Paragraph 1, The above plurality of nut grooves (NV) have a wider groove width the closer they are to the movable plate (120). Mold clamping device (100) for injection molding machine.

4. In Paragraph 1, The above plurality of nut teeth (NT) have a narrower tooth width the closer they are to the movable plate (120). Mold clamping device (100) for injection molding machine.

5. In Paragraph 1, Among the plurality of nut grooves (NV), the groove width of at least three nut grooves (NV) adjacent to the movable plate (120) is different from the groove width of the remaining nut grooves (NV), and the groove width is wider the closer it is to the movable plate (120). Mold clamping device (100) for injection molding machine.

6. In Paragraph 1, Among the plurality of nut teeth (NV), the tooth width of at least three nut teeth (NT) adjacent to the movable plate (120) is different from the tooth width of the remaining nut teeth (NT), and the tooth width becomes narrower the closer it is to the movable plate (120). Mold clamping device (100) for injection molding machine.

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