Lubrication head and piston
The piston head with a lubrication circuit and modified seal ring design addresses inadequate lubrication in die casting machines by redirecting lubricant flow to the front of the container, ensuring consistent lubrication and preventing blockages, even under high stress and temperature conditions.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- COPROMEC DIE CASTING S R L A SOCIO UNICO
- Filing Date
- 2024-05-22
- Publication Date
- 2026-06-04
AI Technical Summary
Conventional lubrication systems for die casting pistons fail to provide adequate lubrication in presses with limited strokes or special designs, especially under high temperature and stress, leading to poor lubrication at the final container portion where the piston slides.
A piston head with a lubrication circuit featuring ring lock projections and a modified seal ring design that redirects lubricant flow to the front of the container, ensuring consistent lubrication even under axial loads and wear, using a lubrication end duct and surface channel system.
The solution effectively lubricates the entire sliding surface of the piston, preventing blockages and ensuring smooth operation in presses with limited strokes or special designs, even under high stress and temperature conditions.
Smart Images
Figure 2026518210000001_ABST
Abstract
Description
Technical Field
[0001]
[0001] The present invention relates to a piston head and a piston for pressing in, for example, a cold chamber type die casting machine. In particular, the present invention aims at a piston provided with a lubrication circuit suitable for promoting the sliding of the piston into the container of molten metal of the press for the die casting machine.
Background Art
[0002]
[0002] In WO2021144722A1 with the same applicant's name, a piston for a die casting machine is proposed, which includes a piston head having a side wall provided with a ring sheet that houses a seal ring suitable for forming a seal on the wall of the container where the piston slides. The ring sheet is delimited at the rear by an annular shoulder. The lubrication circuit is provided in the head and is suitable for promoting the sliding of the piston in the container of the die casting machine.
[0003]
[0003] The lubrication circuit includes at least one lubrication end duct that leads to a surface channel extending through the bottom wall of the ring sheet so as to carry the lubricant towards the gap between the annular shoulder and the seal ring.
[0004]
[0004] Such an embodiment of the piston makes it possible to at least partially solve the problem of complete blockage of the opening of the end duct under the ring and / or the gap from which the lubricant should escape, especially when the axial and radial loads received by the seal ring are large.
[0005]
[0005] However, the applicant has found that, especially in the case of a press with a limited stroke or a specially designed press, or in the case of an extremely stressful molding cycle with high temperature and rhythm, the lubricant leaking from the gap between the rear annular shoulder and the seal ring does not always ensure the desired lubrication at the front of the container where the piston slides.
[0006]
[0006] Problems that arise in projects where the machine stroke is limited, or where the design of the container and shaft prevents the head and seal ring from partially or completely detaching from the container on the mold side, are actually related to poor lubrication of this final container portion.
[0007]
[0007] Furthermore, in some embodiments, the piston head is provided with a channel or passage connecting the front wall of the head to the ring seat to facilitate the flow of metal under the seal ring, in order to progressively compensate for wear that could occur as metal flowing under the seal ring reaches the lower end duct opening and / or gap from which lubricant is to escape, potentially causing blockage.
[0008]
[0008] The object of the present invention is to propose a piston head that has a lubrication circuit but can overcome the limitations and drawbacks of conventional lubrication piston heads.
[0009]
[0009] This objective is achieved by the piston head described in claim 1, the piston described in claim 12, and the seal ring described in claim 13.
[0010]
[0010] The features and advantages of the piston head, piston, and ring according to the present invention will become apparent from the description provided below, which is given as a non-limiting example of a preferred embodiment thereof with reference to the accompanying drawings. The drawings are as follows. [Brief explanation of the drawing]
[0011] [Figure 1]
[0011] Figure 1 is a perspective view of a piston head according to the present invention in one embodiment. [Figure 2]
[0012] Figure 2 is a side view of the piston in Figure 1. [Figure 3]
[0013] Figure 3 is a side view of a section of the piston head. [Figure 3a]
[0014] Figure 3a is a magnified view of detail A, which is circled in Figure 3. [Figure 4]
[0015] Figure 4 is a perspective view of the piston head shown in the preceding figure, with a seal ring attached to the front of the piston head. [Figure 4a] Figure 4a is a side view of the piston head shown in the preceding figure, with a seal ring attached to the front of the piston head. [Figure 5]
[0016] Figure 5 is a side view of the head shown in Figures 4 and 4a, with the sealing ring indicated in the axial section. [Figure 6]
[0017] Figure 6 is an exploded perspective view of the print head. [Figure 7]
[0018] Figure 7 is a perspective view of the head's seal ring only. [Figure 7a] Figure 7a is an end view of only the seal ring of the head. [Figure 7b] Figure 7b is a front view of only the seal ring of the head. [Figure 7c] Figure 7c is an axial cross-sectional view of only the seal ring of the head. [Figure 8]
[0019] Figure 8 is a side view of an example of a piston equipped with a head according to the present invention. [Figure 9]
[0020] Figure 9 is a cross-sectional view of the piston shown in Figure 8. [Figure 10]
[0021] Figure 10 is an enlarged view of detail G in Figure 9.
[0012]
[0022] Referring to the attached drawings, 1 represents a piston head for manufacturing a piston 2 for a cold chamber type die-casting machine press, an example of which is shown in Figures 8 to 10.
[0013]
[0023] The press comprises a container in which at least one of the piston 2 or its end for pressing the molten metal is slidably accommodated.
[0014]
[0024] The piston head 1 comprises a head body 10 having a side wall 12 extending around the head axis X. The head body 10 terminates at the front with a front wall 13 for pressing the molten metal.
[0015]
[0025] In the following description, the terms "front" and "rear", or terms equivalent thereto, mean the forward direction of the piston 2 during the step of pressing the molten metal.
[0016]
[0026] A ring sheet 14 is provided on the side wall 12, and this ring sheet is suitable for receiving respective seal rings 16. The ring sheet 14 forms a bottom wall 18.
[0017]
[0027] At least one ring lock projection 4 suitable for being engaged by respective through openings 6 provided in the seal ring 16 extends from the bottom wall 18.
[0018]
[0028] In some embodiments, the piston head 10 is provided with two ring lock projections 4 diametrically opposed to each other.
[0019]
[0029] In other embodiments, the piston head 10 is provided with three or more ring lock projections 4 uniformly distributed along the periphery of the piston head 10.
[0020]
[0030] At least one ring lock projection 4, as described below, in combination with other ring lock elements, restrains or helps to restrain the seal ring 16 in both the axial and angular directions.
[0021]
[0031] For example, the ring lock projection 4 extends from the cylindrical portion 18a of the bottom wall 18.
[0022]
[0032] In one embodiment, each ring lock projection 4 extends radially with respect to the head axis X. In the embodiment shown in the figure, each ring lock projection 4 is in the form of a right-angled prism, that is, it has a wall perpendicular to the bottom wall 18.
[0023]
[0033] In one embodiment, the ring lock projection 4, in the form of a right-angled prism, has a base with two larger sides 4' that are parallel to each other and perpendicular to the head axis X, i.e., have a main extension along the circumference of the bottom wall 18 of the ring seat 14. In one embodiment, the two larger sides 4' are connected only by a semicircular side 4''. In other words, the ring lock projection 4 has a substantially rectangular cross-section, with the smaller side 4'' being rounded.
[0024]
[0034] The lubrication circuit 20 is located inside the head body 10 and is suitable for promoting the sliding of the piston 2 into the container of the die-casting machine.
[0025]
[0035] According to one embodiment, the lubrication circuit 20 includes at least one lubrication end duct 22 at the base of the ring lock projection 4 that leads to the bottom wall 18, so that when the seal ring 16 is attached to the head, the lubricant escapes from the piston head through the gap 23 between the ring lock projection 4 and the respective through holes 6.
[0026]
[0036] In one embodiment, at least one lubrication end duct 22 extends through the bottom wall 18 and connects to a surface channel 24 that terminates at the base of a ring lock projection.
[0027]
[0037] In the example shown in the drawing, two lubrication end ducts 22, which extend parallel to each other and perpendicular to the head axis X, connect to the surface channel 24.
[0028]
[0038] For example, the surface channel 24 extends axially, that is, parallel to the head axis X.
[0029]
[0039] In one embodiment, the ring sheet 14 is separated at the rear by an annular shoulder portion 26. The ring lock projection is spaced axially apart from the annular shoulder portion. In other words, the ring lock projection is positioned in front of the annular shoulder portion 26.
[0030]
[0040] In one embodiment, at least one lubrication end duct 22 leads to a point on the bottom wall 18 between the annular shoulder 26 and the ring lock projection 4. Thus, the surface channel 24 extends between the opening of the lubrication end duct 22 provided in the bottom wall 18 (i.e., from the rearmost opening in the case of multiple lubrication end ducts 22) and the base of the ring lock projection 44.
[0031]
[0041] In one embodiment, the ring lock projection forms an axial recess 28 in the surface channel 24 that is suitable for locally increasing the lubricant passage section in the gap 23 between the ring lock projection 4 and the seal ring 16.
[0032]
[0042] In other words, a recessed region, or groove, is formed on the rear vertical wall of the ring lock projection 4, extending from the front end of the surface channel 24. Therefore, this axial recess 28 forms a special passage for lubricant to escape. This passage is not blocked by the seal ring 16, even when the seal ring 16 is subjected to an axial load.
[0033]
[0043] More specifically, the surface channel 24 terminates on one of the larger sides 4' of the ring lock projection. In one embodiment, the end of the surface channel 22 and the ring lock projection 4 jointly form a recessed area 29 that extends mainly along the longer side 4'. In other words, when viewed in plan, the surface channel 24 takes on a "T" shape.
[0034]
[0044] In one embodiment, the ring seat 14 is provided with an annular groove 30 positioned forward of at least one ring lock projection 4, which is suitable for engagement by a complementary annular rib 32 formed on the seal ring 16.
[0035]
[0045] Furthermore, in one embodiment, a plurality of metal inflow channels 34 connect the annular portion 13' of the front wall 13 of the piston head 10 to a ring sheet 14 for storing metal below the seal ring 16, and these channels lead to the front distal portion 18b of the bottom wall 18 of the ring sheet 14. This accumulation of metal below the seal ring 16 forms a thickness that, as it solidifies, progressively compensates for the thinning of the seal ring 16 due to wear.
[0036]
[0046] Therefore, in one embodiment, the bottom wall 18 can be distinguished from a rear portion 18a, for example, a cylindrical shape, which is separated at the rear by an annular shoulder portion 26e on which at least one ring lock projection 4 is provided, an intermediate portion 18c, which forms a cylindrical annular groove 30, for example, and a front portion 18b through which a metal inflow channel or passage 34 passes. For example, the front portion 18b is separated at the front by an anterior annular shoulder portion 36.
[0037]
[0047] In one embodiment, at least one ring lock projection 4 is provided near the trailing edge defining the annular groove 30.
[0038]
[0048] The present invention also relates to the piston head 10 as described above, and further provides the piston head 10 with at least one seal ring 16 suitable for being housed in a ring seat 14.
[0039]
[0049] The seal ring 16 is in the form of a band, that is, it has an axial extension that is much larger than its thickness. The seal ring 16 is made of, for example, a copper alloy.
[0040]
[0050] At least one ring lock opening 6 suitable for shape coupling engagement by each ring lock projection 4 is formed in the seal ring, resulting in a gap 23 being formed between at least a portion (at least the rear) of the edge defining the ring lock opening and the respective walls of the ring lock projections for lubrication to escape.
[0041]
[0051] In one embodiment, the seal ring 16 has a substantially cylindrical outer wall 16'. At least one ring lock opening 6 is provided in the intermediate annular portion 16a of the seal ring 16, which has an outer wall that is lower than the adjacent front portion 16b and rear portion 16c of the outer wall 16'.
[0042]
[0052] For example, the intermediate annular portion 16a has a width of 5% to 40% of the total width of the seal ring 16 and a depth of 2% to 40% of the thickness of the seal ring 16.
[0043]
[0053] Due to this lowered area of the seal ring 16, the lubricant escaping from the ring lock opening 6 is partially retained within this lowered zone and is therefore guided to lubricate the entire cylindrical wall 16' of the seal ring 16.
[0044]
[0054] As described above, the annular rib 32 extends from the inner wall of the seal ring 16, which is suitable for engaging with the annular groove 30 provided in the ring seat 14.
[0045]
[0055] The interaction between the annular groove 30 and the annular rib 32 helps to lock the seal ring 16 in the axial direction and helps to prevent molten metal flowing into the front portion 18b of the bottom wall 18 of the ring seat 14 from passing through to the rear portion 18a of this bottom wall 18 and closing the opening of the lubrication end duct 22.
[0046]
[0056] In one embodiment, the seal ring 16 is interrupted by a longitudinal gap (not shown) that allows the ring to be opened and then fitted onto the piston head 1 to position the piston head 1 within the ring seat 14.
[0047]
[0057] In one embodiment, the lubrication circuit 20 provided within the head body 10 includes, for example, at least one proximal duct 40 parallel to the head axis X, the proximal duct 40 originating from or connected to each lubrication duct 42 provided within the shaft. From such a proximal duct 40, two end ducts 22 extend radially parallel to each other and both connect to a surface channel 24.
[0048]
[0058] Figures 8 to 10 show an example of a piston 2 for pressing in a die-casting machine. The piston 2 comprises a head 100 as described above and a shaft 50 extending between a rear or proximal end 50' and a front or distal end 50'' for connecting to the head 100.
[0049]
[0059] In one embodiment, the head 100 is attached to a support pin (not shown) attached to the front end 50" of the shaft 50.
[0050]
[0060] For example, one or more lubricant supply ducts 42, which are fluidly connected to the lubrication end duct 22 by a connecting bush 44, are provided inside the shaft 50.
[0051]
[0061] In one embodiment, the die-casting machine is equipped with an anti-rotation device configured to maintain the piston at an angular position such that the ring lock opening 6 from which the lubricant escapes faces upward. In this way, when the lubricant reaches the upper outer surface of the seal ring, it flows along the entire outer wall by gravity, thereby providing a uniform lubrication effect.
[0052]
[0062] With respect to conventional lubricating pistons, the aforementioned piston head allows the lubricant, which was previously constrained to exit at the rear of the band, to be delivered to a more advanced position. Therefore, using this technical means, it was possible to move the lubricant exit point forward under the same conditions.
[0053]
[0063] This makes it possible to lubricate the final part of the container, which is normally drier, especially in presses with limited strokes, or dies with a third plate, or dies with a special design, or in highly stressful molding cycles with high temperatures and rhythms.
[0054]
[0064] The presence of the ring lock projection protects the lubricant outlet hole from molten metal, even if the lubricant manages to pass over the inner ribs of the band.
[0055]
[0065] The lower area of the seal ring where the ring lock opening is provided allows the lubricant to slide more easily toward the bottom of the chamber, thus enabling better lubrication of its entire surface.
[0056]
[0066] Those skilled in the art can, without departing from the scope of the following claims, make some modifications, adjustments, adaptations, and substitutions of elements with other embodiments of the piston head, piston, and seal ring according to the present invention to satisfy incidental needs. Each of the features described as belonging to a possible embodiment may be obtained independently of other described embodiments.
Claims
1. A piston head for manufacturing a piston (2) for a die-casting press, - A head body (10) having side walls (12) extending around the head axis (X), - A seal ring (16) having at least one ring lock through opening (6), - A ring sheet (14) is provided on the side wall and is suitable for receiving the seal ring (16), and the ring sheet forms a bottom wall (18), from which at least one ring lock projection (4) extends in a manner suitable for engaging with each lock through-opening (6) provided in the seal ring (16), thereby creating a gap (23) between at least a portion of the edge defining the ring lock through-opening (6) and each wall of the ring lock projection (4). - The head body is provided with a lubrication circuit (20) suitable for promoting the sliding of the pistons within each container of the die-casting machine, The lubrication circuit includes at least one lubrication end duct (22) at the base of the ring lock projection (4) that leads to the bottom wall (18) so that when the ring is attached to the head, the lubricant escapes from the piston head through the gap (23), The piston head is characterized in that the seal ring has a substantially cylindrical outer wall, and the at least one ring lock opening (6) is provided in an intermediate annular portion (16a) of the seal ring having an outer wall that is lower than adjacent front and rear portions of the outer wall.
2. The piston head according to claim 1, wherein the at least one lubrication end duct (22) extends through the bottom wall (18) and connects to a surface channel (24) terminating at the base of the ring lock projection.
3. The piston head according to claim 1 or 2, wherein the ring seat (14) is separated at the rear by an annular shoulder (26), and the ring lock projection is spaced axially apart from the annular shoulder.
4. The piston head according to claim 2 or 3, wherein the at least one lubrication end duct (22) leads to a point on the bottom wall (18) between the annular shoulder (26) and the ring lock projection (4).
5. The piston head according to any one of claims 2 to 4, wherein the surface channel (24) extends parallel to the head axis (X).
6. The piston head according to any one of claims 1 to 5, wherein each ring lock projection (4) has a prismatic shape, and its base has a long side that is parallel to each other and perpendicular to the head axis (X).
7. The piston head according to any one of claims 1 to 6, wherein the ring lock projection forms an axial recess (28) in the surface channel that is suitable for locally increasing the passage section of the lubricant in the gap (23) between the ring lock projection and the seal ring.
8. The piston head according to claim 6 or 7, wherein the surface channel (24) terminates at one of the long sides of the ring lock projection (4), and the end of the surface channel and the ring lock projection jointly form a recessed area (29) that extends mainly along the long side.
9. The piston head according to any one of claims 1 to 8, wherein an annular groove (30) suitable for engagement by a complementary annular rib (32) provided on the seal ring (16) is provided on the ring seat (14) in front of the at least one ring lock projection (4).
10. A piston head according to any one of claims 1 to 9, wherein a plurality of metal inflow channels (34) connect the annular portion (13') of the front wall (13) of the piston head to the ring seat (14) for storing metal below the seal ring (16), and these channels extend to the anterior distal portion (18b) of the bottom wall (18) of the ring seat (14).
11. The piston head according to any one of claims 1 to 10, wherein the seal ring is interrupted by a longitudinal gap.
12. A piston for a die-casting machine, comprising a head according to any one of claims 1 to 11, and a shaft (50) extending between a rear end and a front end connected to a head assembly, wherein one or more lubricant supply ducts (42) are provided within the shaft and are fluidly connected to the lubrication end duct (22).
13. A seal ring that can be positioned on a ring seat provided on the piston of a press for a die-casting machine, comprising a substantially cylindrical side wall interrupted by a longitudinal gap, the cylindrical wall having at least one through-opening (6) suitable for shape-coupled engagement by respective ring lock projections (4) provided on the ring seat, the at least one through-opening (6) being provided on an intermediate annular portion (16a) of the seal ring having an outer wall that is lower than adjacent front and rear portions of the outer wall.
14. The seal ring according to claim 13, wherein the intermediate annular portion (16a) has an axial length of 5% to 40% of the total width of the seal ring (16) and a depth of 2% to 40% of the thickness of the seal ring (16).